types of volcano essay

ENCYCLOPEDIC ENTRY

A volcano is an opening in a planet or moon’s crust through which molten rock and gases trapped under the surface erupt, often forming a hill or mountain.

Volcanic eruption

Volcanic eruptions can create colorful and dramatic displays, such as this eruption of this volcano in the Virunga Moutains of the Democratic Republic of the Congo.

Photograph by Chris Johns

A volcano is an opening in a planet or moon’s crust through which molten rock, hot gases, and other materials erupt . Volcanoes often form a hill or mountain as layers of rock and ash build up from repeated eruptions .

Volcanoes are classified as active, dormant, or extinct. Active volcanoes have a recent history of eruptions ; they are likely to erupt again. Dormant volcanoes have not erupted for a very long time but may erupt at a future time. Extinct volcanoes are not expected to erupt in the future.

Inside an active volcano is a chamber in which molten rock, called magma , collects. Pressure builds up inside the magma chamber, causing the magma to move through channels in the rock and escape onto the planet’s surface. Once it flows onto the surface the magma is known as lava .

Some volcanic eruptions are explosive, while others occur as a slow lava flow. Eruptions can occur through a main opening at the top of the volcano or through vents that form on the sides. The rate and intensity of eruptions, as well as the composition of the magma, determine the shape of the volcano.

Volcanoes are found on both land and the ocean floor. When volcanoes erupt on the ocean floor, they often create underwater mountains and mountain ranges as the released lava cools and hardens. Volcanoes on the ocean floor become islands when the mountains become so large they rise above the surface of the ocean.

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Types of Volcanoes

Understanding the different types of volcanoes and their characteristics provides insight into Earth’s geology, aids in hazard prediction and risk management, and helps us to appreciate the dynamic nature of the planet we inhabit.

How Many Types of Volcanoes Are There?

How many types of volcanoes there are depends on who you ask. The three main types of volcanoes are cinder cones, composite volcanoes (stratovolcanoes) and shield volcanoes. Lava domes are a common fourth type of volcano. However, there are other kinds of volcanoes, plus they are compound or complex volcanoes that have features of multiple types. For example, Trident Volcano in Alaska is a complex volcano that include stratovolcanoes and lava domes.

Main Types of Volcanoes

The types of volcanoes vary according to their size and how they erupt. Cinder cones often erupt only once, composite volcanoes erupt infrequently, and shield volcanoes erupt the most often. Cinder cones erupt rocks and gas, without flowing lava. Composite volcanoes erupt thick lava and rocks, while shield volcanoes erupt fluid lava .

Cinder Cones (Scoria Cones)

Cinder cones are the simplest and most common type of volcano. They form as a single eruption vent expels volcanic debris, including ash, cinders, and volcanic rocks. The accumulation of debris forms the cone shape.

• Description : Smallest type, steep sides built from loose volcanic debris from single eruption vent.
• Examples : Paricutin in Mexico
• Size : Generally less than 400 meters tall.
• Magma Composition : Basaltic to andesitic.
• Eruption Frequency : May erupt only once.

Composite Volcanoes (Stratovolcanoes)

Composite volcanoes or stratovolcanoes have the classic “volcano” shape. They are tall, symmetrical cones. Stratovolcanoes form by the accumulation of different types of volcanic materials, including lava, ash, and rock. Their eruptions can be violent.

• Description : Large, symmetrical, steep-sided mountains formed by layers of lava, ash, and volcanic rocks.
• Examples : Mount Fuji in Japan, Mount St. Helens in the United States
• Size : Up to several kilometers in height.
• Magma Composition : Andesitic to rhyolitic.
• Eruption Frequency : Less frequent, more explosive than cinder cones.

Shield Volcanoes

The largest volcanoes are shield volcanoes. These colossal volcanoes boast gentle sloping sides created by the flow of highly fluid basaltic lava. Their eruptions produce extensive lava flows.

• Description : Large, broad, gentle slopes formed by fluid basaltic lava flows.
• Examples : Mauna Loa, Mauna Kea, and Kilauea in Hawaii; Olympus Mons on Mars
• Size : Several kilometers in height and up to 100 km wide.
• Magma Composition : Basaltic.
• Eruption Frequency : Frequent, less explosive eruptions.

Lava Domes (Volcanic Domes)

Lava domes form by the slow oozing of highly viscous lava. They are smaller formations, with steep sides, and often form within the craters of larger volcanoes.

• Description : Small, steep-sided mounds where viscous lava piles up near the vent.
• Examples : Mount St. Helens Lava Dome
• Size : Usually less than 500 meters tall.
• Magma Composition : Rhyolitic or dacitic.
• Eruption Frequency : Variable, usually within the context of larger eruptions.

Other Types of Volcanoes

Cryptodomes.

• Formed by bulging of the volcanic edifice rather than eruptions.

Supervolcanoes

• Extremely large volcanic systems.
• Examples: Yellowstone Caldera in the USA

Submarine Volcanoes

• Located beneath the ocean.
• Examples: Loihi Seamount in Hawaii

Subglacial Volcanoes

• Found under ice caps.
• Examples: Öræfajökull in Iceland

Mud Volcanoes

• Eject mud, water, and gases.
• Examples: Lusi mud volcano in Indonesia

Cryovolcanoes (Ice Volcanoes)

While there are no ice volcanoes on Earth, they exist elsewhere.

• Erupt volatile materials like water or ammonia.
• Examples: Found on Pluto and some moons in our solar system.

Volcanoes in the Solar System

Earth is not the only planet in the solar system with volcanoes:

• Moon : No current activity, but indications of past eruptions
• Mars : Olympus Mons (shield volcano)
• Venus : Numerous shield volcanoes
• Io (Jupiter’s moon) : Hundreds of active volcanoes
• Enceladus (Saturn’s moon) : Cryovolcanoes

Categories of Volcanoes

• Active : An active volcano either is erupting or has a history of recent activity. Earthquake swarms, ground inflation, and carbon dioxide/sulfur dioxide release are indications of activity. Kilauea is an example of an active volcano.
• Dormant : A dormant volcano shows no signs of recent activity, but has potential for erupting in the future. Yellowstone is a dormant volcano. Even though it is an active geothermal site, it goes around 700,000 years between eruptions.
• Extinct : An extinct volcano no long has a magma supply. Shiprock in New Mexico is an example of the remains of an extinct volcano.

Types of Volcanic Eruptions

The broad types of volcanic eruptions are magmatic, phreatomagmatic, and phreatic, but vulcanologists subdivide eruptions either by names or numbers. The Volcanic Explosivity Index (VEI) ranges from 0 for a Hawaiian-type (shield volcano eruption) to an 8 for a supervolcano eruption.

Magmatic Eruptions

• Involves the eruption of magma, mainly from decompression of gases.

Hawaiian Eruption

• Fluid lava flows, effusive.
• Examples: Mauna Loa in Hawaii.

Strombolian Eruption

• Mildly explosive, lava fountains and gas bursts.
• Examples: Mount Stromboli in Italy.

Vulcanian Eruption

• Explosive eruptions producing ash and volcanic bombs.
• Examples: Sakurajima in Japan.

Peléan Eruption

• Eruption with pyroclastic flows.
• Examples: Mount Pelée in Martinique.

Plinian Eruption

• Extremely explosive, large amounts of ash and gas.
• Examples: Mount Vesuvius in Italy.

Phreatomagmatic Eruption

• Interaction of magma with water, explosive.
• Examples: Taal Volcano in the Philippines.

Phreatic Eruption

• Steam-driven eruptions or rock without magma.
• Examples: Mount Ontake in Japan.
• Francis, Peter (1983). “Giant Volcanic Calderas”. Scientific American . 248 (6): 60–73. doi: 10.1038/scientificamerican0683-60
• Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of Igneous and Metamorphic Petrology (2nd ed.). Cambridge, UK: Cambridge University Press. ISBN 9780521880060.
• Schmincke, Hans-Ulrich (2003). Volcanism . Berlin: Springer. ISBN 9783540436508.
• Schmidt, R. (1981). “Descriptive nomenclature and classification of pyroclastic deposits and fragments: recommendations of the IUGS Subcommission on the Systematics of Igneous Rocks”. Geology . 9: 41–43. doi: 10.1007/BF01822152
• Sigurðsson, Haraldur, ed. (2015). The Encyclopedia of Volcanoes (2nd ed.). Academic Press. ISBN 978-0-12-385938-9.

Related Posts

Essays About Volcanoes: Top 5 Examples and 10 Prompts

Do you need to write essays about volcanoes but don’t know where to start? Check out our top essay examples and prompts to help you write a high-quality essay.

Considered the planet’s geologic architects, volcanoes are responsible for more than 80% of the Earth’s surface . The mountains, craters, and fertile soil from these eruptions give way to the very foundation of life itself, making it possible for humans to survive and thrive.  

Aside from the numerous ocean floor volcanoes, there are 161 active volcanoes in the US . However, these beautiful and unique landforms can instantly turn into a nightmare, like Mt. Tambora in Indonesia, which killed 92,000 people in 1815 .

Various writings are critical to understanding these openings in the Earth’s crust, especially for students studying volcanoes. It can be tricky to write this topic and will require a lot of research to ensure all the information gathered is accurate. 

To help you, read on to see our top essay examples and writing prompts to help you begin writing.

Top 5 Essay Examples

1. short essay on volcanoes by prasad nanda , 2. types of volcanoes by reena a , 3. shield volcano, one of the volcano types by anonymous on gradesfixer.com, 4. benefits and problems caused by volcanoes by anonymous on newyorkessays.com, 5. volcanoes paper by vanessa strickland, 1. volcanoes and their classifications, 2. a dormant volcano’s eruption, 3. volcanic eruptions in the movies, 4. the supervolcano: what is it, 5. the word’s ring of fire, 6. what is a lahar, 7. why does a volcano erupt, 8. my experience with volcanic eruptions, 9. effects of volcanic eruptions, 10. what to do during volcanic disasters.

“The name, “volcano” originates from the name Vulcan, a god of fire in Roman mythology.”

Nanda briefly defines volcanoes, stating they help release hot pressure that builds up deep within the planet. Then, he discusses each volcano classification, including lava and magma’s roles during a volcanic eruption. Besides interesting facts about volcanoes (like the Ojos del Salado as the world’s tallest volcano), Nanda talks about volcanic eruptions’ havoc. However, he also lays down their benefits, such as cooled magma turning to rich soil for crop cultivation.

“The size, style, and frequency of eruptions can differ greatly but all these elements are correlated to the shape of a volcano.”

In this essay, Reena identifies the three main types of volcanoes and compares them by shape, eruption style, and magma type and temperature. A shield volcano is a broad, flat domelike volcano with basaltic magma and gentle eruptions. The strato or composite volcano is the most violent because its explosive eruption results in a lava flow, pyroclastic flows, and lahar. Reena shares that a caldera volcano is rare and has sticky and cool lava, but it’s the most dangerous type. To make it easier for the readers to understand her essay, she adds figures describing the process of volcanic eruptions.

“All in all, shield volcanoes are the nicest of the three but don’t be fooled, it can still do damage.”

As the essay’s title suggests, the author focuses on the most prominent type of volcano with shallow slopes – the shield volcano. Countries like Iceland, New Zealand, and the US have this type of volcano, but it’s usually in the oceans, like the Mauna Loa in the Hawaiian Islands. Also, apart from its shape and magma type, a shield volcano has regular but calmer eruptions until water enters its vents.

“Volcanic eruptions bring both positive and negative impacts to man.”

The essay delves into the different conditions of volcanic eruptions, including their effects on a country and its people. Besides destroying crops, animals, and lives, they damage the economy and environment. However, these misfortunes also leave behind treasures, such as fertile soil from ash, minerals like copper, gold, and silver from magma, and clean and unlimited geothermal energy. After these incidents, a place’s historic eruptions also boost its tourism.

“Beautiful and powerful, awe-inspiring and deadly, they are spectacular reminders of the dynamic forces that shape our planet.”

Strickland’s essay centers on volcanic formations, types, and studies, specifically Krakatoa’s eruption in 1883. She explains that when two plates hit each other, the Earth melts rocks into magma and gases, forming a volcano. Strickland also mentions the pros and cons of living near a volcanic island. For example, even though a tsunami is possible, these islands are rich in marine life, giving fishermen a good living.

Are you looking for more topics like this? Check out our round-up of essay topics about nature .

10 Writing Prompts For Essays About Volcanoes

Do you need more inspiration for your essay? See our best essay prompts about volcanoes below:

Identify and discuss the three classifications of volcanoes according to how often they erupt: active, dormant or inactive, and extinct. Find the similarities and differences of each variety and give examples. At the end of your essay, tell your readers which volcano is the most dangerous and why.

Volcanoes that have not erupted for a very long time are considered inactive or dormant, but they can erupt anytime in the future. For this essay, look for an inactive volcano that suddenly woke up after years of sleeping. Then, find the cause of its sudden eruption and add the extent of its damage. To make your piece more interesting, include an interview with people living near dormant volcanoes and share their thoughts on the possibility of them exploding anytime.

Choose an on-screen depiction of how volcanoes work, like the documentary “ Krakatoa: Volcano of Destruction .” Next, briefly summarize the movie, then comment on how realistic the film’s effects, scenes, and dialogues are. Finally, conclude your essay by debating the characters’ decisions to save themselves.

The Volcanic Explosivity Index (VEI) criteria interpret danger based on intensity and magnitude. Explain how this scale recognizes a supervolcano. Talk about the world’s supervolcanoes, which are active, dormant, and extinct. Add the latest report on a supervolcano’s eruption and its destruction.

Identify the 15 countries in the Circum-Pacific belt and explore each territory’s risks to being a part of The Ring of Fire. Explain why it’s called The Ring of Fire and write its importance. You can also discuss the most dangerous volcano within the ring.

If talking about volcanoes as a whole seems too generic, focus on one aspect of it. Lahar is a mixture of water, pyroclastic materials, and rocky debris that rapidly flows down from the slopes of a volcano. First, briefly define a lahar in your essay and focus on how it forms. Then, consider its dangers to living things. You should also add lahar warning signs and the best way to escape it.

Use this prompt to learn and write the entire process of a volcanic eruption. Find out the equipment or operations professionals use to detect magma’s movement inside a volcano to signal that it’s about to blow up. Make your essay informative, and use data from reliable sources and documentaries to ensure you only present correct details.

If you don’t have any personal experience with volcanic eruptions, you can interview someone who does. To ensure you can collect all the critical points you need, create a questionnaire beforehand. Take care to ask about their feelings and thoughts on the situation.

Write about the common effects of volcanic eruptions at the beginning of your essay. Next, focus on discussing its psychological effects on the victims, such as those who have lost loved ones, livelihoods, and properties.

Help your readers prepare for disasters in an informative essay. List what should be done before, during, and after a volcanic eruption. Include relevant tips such as being observant to know where possible emergency shelters are. You can also add any assistance offered by the government to support the victims.Here’s a great tip: Proper grammar is critical for your essays. Grammarly is one of our top grammar checkers. Find out why in this  Grammarly review .

Maria Caballero is a freelance writer who has been writing since high school. She believes that to be a writer doesn't only refer to excellent syntax and semantics but also knowing how to weave words together to communicate to any reader effectively.

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9.5: Types of Volcanoes

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INTRODUCTION

A volcano is a vent through which molten rock and gas escape from a magma chamber. Volcanoes differ in many features such as height, shape, and slope steepness. Some volcanoes are tall cones and others are just cracks in the ground (figure 1). As you might expect, the shape of a volcano is related to the composition of its magma.

COMPOSITE VOLCANOES

Composite volcanoes are made of felsic to intermediate rock. The viscosity of the lava means that eruptions at these volcanoes are often explosive (figure 2).

The viscous lava cannot travel far down the sides of the volcano before it solidifies, which creates the steep slopes of a composite volcano. Viscosity also causes some eruptions to explode as ash and small rocks. The volcano is constructed layer by layer, as ash and lava solidify, one upon the other (figure 3). The result is the classic cone shape of composite volcanoes.

SHIELD VOLCANOES

Shield volcanoes get their name from their shape. Although shield volcanoes are not steep, they may be very large. Shield volcanoes are common at spreading centers or intraplate hot spots (figure 4).

The lava that creates shield volcanoes is fluid and flows easily. The spreading lava creates the shield shape. Shield volcanoes are built by many layers over time and the layers are usually of very similar composition. The low viscosity also means that shield eruptions are non-explosive.

This Volcanoes 101 video from National Geographic discusses where volcanoes are found and what their properties come from:

CINDER CONES

Cinder cones are the most common type of volcano. A cinder cone has a cone shape, but is much smaller than a composite volcano. Cinder cones rarely reach 300 meters in height but they have steep sides. Cinder cones grow rapidly, usually from a single eruption cycle (figure 5). Cinder cones are composed of small fragments of rock, such as pumice, piled on top of one another. The rock shoots up in the air and doesn’t fall far from the vent. The exact composition of a cinder cone depends on the composition of the lava ejected from the volcano. Cinder cones usually have a crater at the summit.

Cinder cones are often found near larger volcanoes (figure 6).

SUPERVOLCANOES

Supervolcano eruptions are extremely rare in Earth history. It’s a good thing because they are unimaginably large. A supervolcano must erupt more than 1,000 cubic km (240 cubic miles) of material, compared with 1.2 km 3 for Mount St. Helens or 25 km 3 for Mount Pinatubo, a large eruption in the Philippines in 1991. Not surprisingly, supervolcanoes are the most dangerous type of volcano.

Supervolcanoes are a fairly new idea in volcanology. The exact cause of supervolcano eruptions is still debated. However, scientists think that a very large magma chamber erupts entirely in one catastrophic explosion. This creates a huge hole or caldera into which the surface collapses (figure 7).

The largest supervolcano in North America is beneath Yellowstone National Park in Wyoming. Yellowstone sits above a hotspot that has erupted catastrophically three times: 2.1 million, 1.3 million, and 640,000 years ago. Yellowstone has produced many smaller (but still enormous) eruptions more recently (figure 8). Fortunately, current activity at Yellowstone is limited to the region’s famous geysers.

Long Valley Caldera, south of Mono Lake in California, is the second largest supervolcano in North America (figure 9). Long Valley had an extremely hot and explosive rhyolite about 700,000 years ago. An earthquake swarm in 1980 alerted geologists to the possibility of a future eruption, but the quakes have since calmed down.

• This site provides and interactive image of the geological features of Long Valley Caldera.

A supervolcano could change life on Earth as we know it. Ash could block sunlight so much that photosynthesis would be reduced and global temperatures would plummet. Volcanic eruptions could have contributed to some of the mass extinctions in our planet’s history. No one knows when the next super eruption will be.

Interesting volcano videos are seen on National Geographic Videos, Environment Video, Natural Disasters, Earthquakes. One interesting one is “Mammoth Mountain,” which explores Hot Creek and the volcanic area it is a part of in California.

LESSON SUMMARY

• Composite, shield, cinder cones, and supervolcanoes are the main types of volcanoes.
• Composite volcanoes are tall, steep cones that produce explosive eruptions.
• Shield volcanoes form very large, gently sloped mounds from effusive eruptions.
• Cinder cones are the smallest volcanoes and result from accumulation of many small fragments of ejected material.
• An explosive eruption may create a caldera, a large hole into which the mountain collapses.
• Supervolcano eruptions are devastating but extremely rare in Earth history.

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Original content from Kimberly Schulte (Columbia Basin College) and supplemented by Lumen Learning . The content on this page is copyrighted under a Creative Commons Attribution 4.0 International license.

The Nature of Volcanoes: Types and Effects

Phenomenon of volcanoes, plate tectonics and volcanoes, types of volcanoes, popular classification of volcanoes, effects of volcanic eruptions.

For centuries, people across different civilizations had been terrified by the display of power that volcanic eruptions present, and they interpreted them as a sign of wrath and vengeance of gods. Clearly, with the progress of the modern science, volcanoes have been demystified; particularly, the development of the plate tectonics theory in the 1960s has played a major role in helping people understand volcanoes. The purpose of the present paper is thus to analyze volcanoes as a natural phenomenon. The first section provides an overview of the features that define a volcano while the second part considers the processes that take place in the Earth’s surface and shape the planet’s volcanic activity. The third and the fourth sections identify the different scientific and popular classifications of volcanoes, and the final part of the paper considers the impact of eruptions both on humans and the environment. The main conclusion is that the processes that create volcanos are so grand and complex that people still have little power to control and mitigate the impact of volcanic eruptions.

Volcanoes are arguably one of the most powerful and awe-inspiring naturally occurring phenomena. Even given the current advances in science and technology, people have little power and control over the volcanic eruptions, apart from the fact that they have learned how to predict them. The present paper analyzes the science behind volcanoes with the purpose of discovering what makes them so powerful over human activities and even lives.

Volcanoes are a naturally occurring phenomenon that are, essentially, a byproduct of the movement of the seventeen tectonic plates that make up the surface of the Earth (Environmental Literacy Council, 2007, p. 6). It is typical to think of volcanoes as cone-shaped mountains that have an opening – a crater – on top of it and that release fire, gas, and lava. In fact, the very name of this phenomenon comes from the name of the Roman god of fire, Vulcan (Lockwood & Hazlett, 2010). While conical volcanoes are, indeed, one of the most frequently occurring types, it is far from being the only one. Essentially, what defines a volcano is not its shape or even the fire and lava that come out of it, but its structural characteristics (Environmental Literacy Council, 2007, p. 6). Volcanoes are, first and foremost, ruptures on the surface of a planet, and, as such, they can take any forms, including that of flat fractures (Hone, Mahony, Sparks & Martin, 2007, p. 204). Moreover, volcanoes are typical not only for the Earth but also to other planetary bodies such as Venus, Mars, and the Earth’s and Jupiter’s moons (Lockwood & Hazlett, 2010). The second defining characteristic is the volcano’s ability to release the planet’s magma, which is essentially hot molten rock (Environmental Literacy Council, 2007, p. 6). This process is known as a volcano eruption.

The central concept related to understanding the phenomenon of volcanoes is the theory of plate tectonics (Gabrieli, Wilson & Lane, 2015). The surface of the Earth is made up of seventeen rigid tectonic plates. Even though the plates themselves are hard, they tend to move and float because they are situated on the Earth’s mantle – a hot and soft layer underneath the plates (Environmental Literacy Council, 2007, p. 6). As the tectonic plates move around, they tend to either converge or diverge, and it is precisely this process that leads to the appearance of volcanoes. On top of that, the Earth’s mantle, because of its extremely hot conditions, has the ability to melt rock and turn it into a thick yet fluid substance called magma (Environmental Literacy Council, 2007, p. 6). This substance is stored in the so-called magma chambers – large pools of magma underneath the Earth’s surface that have high internal pressure. However, as the tectonic plates slide and collide with one another, they disrupt the conditions within the magma chambers, causing the magma to rise and escape through the volcano’s crater (Environmental Literacy Council, 2007, p. 7).

While there is no one universally accepted typology of volcanoes, generally, they are classified on the basis of their size and morphological characteristics (Hone et al., 2007, p. 203). For instance, fissure vents and shield volcanoes have been identified, with the former being flat fractures in the Earth’s surface and the latter being broad-profiled volcanoes. Volcanic cones are arguably the most widely known type since this is the shape that is typically associated with volcanoes. While shield volcanoes are broad at base, stratovolcanoes are the exact opposite to them, as they represent tall cone-shaped structures that have been formed as a result of several eruptions (Lockwood & Hazlett, 2010). Thus, the primary difference between these three types is their shape and height. Another widely studied type is the super volcanoes with large-sized calderas. Because of their size, these volcanoes can produce devastating effects, even at a continental scale. An eruption of such a volcano can significantly impact the Earth’s atmosphere and cool down the planet’s average temperature (Lockwood & Hazlett, 2010). Another common type is the submarine volcanoes that, as their name suggests, can be found on the bottom of the oceans’ floor. In fact, most of the Earth’s volcanoes are located underneath the water’s surface, so submarine volcanoes are among the most frequently occurring kind. However, the list of types mentioned here is not exhaustive since different features can be used as the basis for classification.

The present section is dedicated to exploring one of the most commonly used classifications of volcanoes that is based on their level of volcanic activity. According to this classification, volcanoes can be grouped into active, dormant, and extinct (Lockwood & Hazlett, 2010). While this classification is quite popular, especially in the wider circles, it is considered to be rather problematic in the scientific community. Assigning a certain volcano into one of these categories requires an assessment of the frequency of its eruption. However, the processes that create volcanoes and make them erupt are so complex and grand that it is meaningless to measure them against the lifespan of not only individual humans but even the humankind in general. The least controversial of these categories is the extinct volcanoes because they are defined as such on a comparatively objective basis. Extinct volcanoes are highly unlikely to erupt again because they have exhausted their magma supply (Lockwood & Hazlett, 2010). However, distinguishing between active and dormant volcanoes is a much more difficult task, mainly because the life cycle of a volcano can span across thousands and even millions of years. The prevalent rule is that a volcano is considered dormant if there are no written records of its activity.

Volcanic eruptions present quite a spectacle that, given their devastating capacity, few people would like to witness first-hand. However, the negative effects of volcanic eruptions can also extend far beyond their physical impact. First of all, being tectonic creations, volcanoes are closely linked to earthquakes because of their mechanism of occurrence (Gabrieli, Wilson & Lane, 2015). Apart from that, volcanic eruptions result in the emissions of several gases, such as carbon dioxide, sulfur dioxide, and hydrogen sulfide, to name a few. A high concentration of such gases can have a devastating impact on the agriculture and farming. Moreover, it can also cause acid rains in the affected areas. Secondly, most volcanic eruptions are accompanied with ash plumes resulting from the extremely hot temperatures in and around the volcanoes. Consequently, eruptions may cause a major disturbance in the air traffic as flying under such conditions clearly becomes impossible (Picquout et al., 2013). A moderate amount of ashes can, in fact, be beneficial to the environment because of the problem of climate change: the resulting dust may help mitigate global warming by enhancing the Earth’s albedo potential (Adam, 2010). However, in other cases, ash plumes can be dangerous, and they even have the potential to lead to a volcanic winter.

People have certainly come a long way as far as their ability to comprehend natural phenomena is concerned. Volcanic eruptions, just like tsunamis and earthquakes, tend to be significantly devastating to humans, yet scientific knowledge reveals that there is little that people can do to mitigate their impact. These days, people know that volcanic eruptions are not an act of wrath committed by an angry god; nevertheless, the processes behind volcanoes are so grand that, in comparison to the human lifespan, they may as well be deemed supernatural.

Adam, D. (2010). Volcanic eruptions and ash clouds explained . Web.

Environmental Literacy Council. (2007). Earthquakes, volcanoes, and tsunamis. Web.

Gabrieli, A., Wilson, L., & Lane, S. (2015). Volcano–tectonic interactions as triggers of volcanic eruptions. Proceedings of the Geologists’ Association, 126 (6), 675-682.

Hone, D. W., E., Mahony, S. H., Sparks, R. S., J., & Martin, K. T. (2007). Cladistic analysis applied to the classification of volcanoes. Bulletin of Volcanology, 70 (2), 203-220.

Lockwood, J.P., & Hazlett, R.W. (2010). Volcanoes: Global perspectives. Hoboken, NJ: John Wiley and Sons.

Picquout, A., Lavigne, F., Mei, E.T.W., Grancher, D., Noer, C., Vidal, C.M., & Hadmoko, D.S. (2013). Air traffic disturbance due to the 2010 Merapi volcano eruption. Journal of Volcanology and Geothermal Research, 261 , 366-375.

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StudyCorgi. (2020, May 13). The Nature of Volcanoes: Types and Effects. https://studycorgi.com/the-nature-of-volcanoes-types-and-effects/

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70 Volcano Essay Topic Ideas & Examples

🏆 best volcano topic ideas & essay examples, 📌 most interesting volcano topics to write about, 👍 good research topics about volcano, ❓ essay questions about volcanoes.

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• Chicago (A-D)
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IvyPanda . "70 Volcano Essay Topic Ideas & Examples." October 26, 2023. https://ivypanda.com/essays/topic/volcano-essay-topics/.

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Essay on volcanoes | geology.

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After reading this article you will learn about:- 1. Introduction to Volcanoes 2. Volcano Formation 3. Volcanic Landforms 4. Major Gases Emitted by Volcanoes 5. Lightning and Whirlwinds 6. Features Produced by the Escape of Gases from Volcanic Lavas 7. Volcanic Products 8. Source of the Explosive Energy 9. Classification of Pyroclastics 10. Lahars-Mudflows on Active and Inactive Cones and Other Details.

Essay Contents:

• Essay on the Volcanoes and Atmospheric Pollution

Essay # 1. Introduction to Volcanoes :

A volcano is a cone shaped hill or mountain which is built-up around an opening in the earth’s surface through which hot gases, rock fragments and lavas are ejected.

Due to the accumulation of the solid fragments around the conduit a conical mass is built which increases in size to become a large volcanic mountain. The conical mass so built-up is called a volcano. However the term volcano is taken to include not only the central vent in the earth but also the mountain or hill built around it.

Volcanoes are in varying sizes, varying from small conical hills to loftiest mountains on the earth’s surface. The volcanoes of the Hawaiian Islands are nearly 4300 metres above sea level since they are built over the floor of the Pacific ocean which at the site is 4300 to 5500 metres deep, the total height of the volcano may be about 9000 m or more.

The very high peaks in the Andes, in the Cascade Range of the Western United States, Mt. Baker, Mt. Adams, Mt. Hood etc. are all volcanoes which have now become extinct. Over 8000 independent eruptions have been identified from earth’s volcanoes. There are many inaccessible regions and ocean floors where volcanoes have occurred undocumented or unnoticed.

The eruption of a volcano is generally preceded by earthquakes and by loud rumblings like thunder which may continue on a very high scale during the eruption. The loud rumblings are due to explosive movement of gases and molten rock which are held under very high pressure. Before eruption of a volcano fissures are likely to be opened, nearby lakes likely to be drained and hot springs may appear at places.

The eruptive activity of volcanoes is mostly named after the well-known volcanoes, which are known for particular type of behaviour, like Strambolian, Vulcanian, Vesuvian, Hawaiian types of eruption. Volcanoes may erupt in one distinct way or may erupt in many ways, but, the reality is, these eruptions provide a magical view inside the earth’s molten interior.

The nature of a volcanic eruption is determined largely by the type of materials ejected from the vent of the volcano. Volcanic eruptions may be effusive (fluid lavas) or dangerous and explosive with blasts of rock, gas, ash and other pyroclasts.

Some volcanoes erupt for just a few minutes while some volcanoes spew their products for a decade or more. Between these two main types viz. effusive and explosive eruptions, there are many subdivisions like, eruption of gases mixed with gritty pulverised rock forming tall dark ash clouds seen for many kilometres, flank fissure eruptions with lava oozing from long horizontal cracks on the side of a volcano.

There is also the ground hugging lethally hot avalanches of volcanic debris called pyroclastic flows. When magma rises, it may encounter groundwater causing enormous phreatic, i.e., steam eruptions. Eruptions may also release suffocating gases into the atmosphere. Eruptions may produce tsunamis and floods and may trigger earthquakes. They may unleash ravaging rockslides and mudflows.

Volcanoes which have had no eruptions during historic times, but may still show fairly fresh signs of activity and have been active in geologically recent times are said to be dormant. There are also volcanoes which were formerly active but are of declining activity a few of which may be emitting only steam and other gases.

Geysers are hot springs from which water is expelled vigorously at intervals and are characteristics of regions of declining volcanic activity. Geysers are situated in Iceland, the Yellowstone park in USA and in New Zealand.

In contrast to the explosive type of volcanoes, there exist eruptions of great lava flows quietly pouring out of fissures developed on the earth’s surface. These eruptions are not accompanied by explosive outbursts. These are fissure eruptions.

Ex: Deccan Trap formations in India. The lavas in these cases are mostly readily mobile and flow over low slopes. The individual flows are seldom over a few meters in thickness; the average thickness may be less than 15 meters. If the fissure eruptions have taken place in valleys however, the thickness may be much greater.

A noteworthy type of volcano is part of the world encircling mid-ocean ridge (MOR) visible in Iceland. The MOR is really a single, extremely long, active, linear volcano, connecting all spreading plate boundaries through all oceans. Along its length small, separate volcanoes occur. The MOR exudes low-silica, highly fluid basalt producing the entire ocean floor and constituting the largest single structure on the face of the earth.

Essay # 2. Location of Volcanoes:

Volcanoes are widely distributed over the earth, but they are more abundant in certain belts. One such belt encircles the Pacific ocean and includes many of the islands in it. Other volcanic areas are the island of West Indies, those of the West coast of Africa, the Mediterranean region and Iceland.

Most volcanoes occur around or near the margins of the continents and so these areas re regarded as weak zones of the earth’s crust where lavas can readily work their way upward. There are over 400 active volcanoes and many more inactive ones. Numerous submarine volcanoes also exist.

Since it is not possible to examine the magma reservoir which fees a volcano our information must be obtained by studying the material ejected by the volcano. This material consists of three kinds of products, viz. liquid lava, fragmented pyroclasts and gases. There may exist a special problem in studying the gases, both in collecting them under hazardous conditions or impossible conditions.

It may also be difficult to ascertain that the gases collected are true volcanic gases and are not contaminated with atmospheric gases. Investigation of the composition of extruded rock leads to a general, although not very detailed, correlation between composition and intensity of volcanic eruption.

In general, the quite eruptions are characteristic of those volcanoes which emit basic or basaltic lavas, whereas the violent eruptions are characteristic of volcanoes emitting more silicic rocks.

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Essay # 3 . formation of volcanoes :.

The term volcano is used to mean both the opening in the earth’s crust, i.e. the vent through which the eruption of magma occurs as well as the hill built- up by the erupted material. Volcanoes occur where the cracks in the earth’s crust lead to the magma chamber.

The liquid magma which is lighter than the surrounding rocks is under high pressure is pushed up towards the surface through these cracks. In this process the gases dissolved in the magma which expand are released providing an upward push to the magma.

As the magma gets closer to the surface, due to the reducing confining pressure to overcome, the magma and the gases flow faster. The magma, depending on its viscosity may quietly pour to the surface in the form of a flood of molten rock or it may explosively spurt out the molten rock to considerable heights as showers on the surrounding region with solid rock fragments and globs of molten rock. The liquid magma discharged to the surface is called lava.

Essay # 4 . Volcanic Landforms :

Many surface features of volcanic origin are created. These features range from towering peaks and huge lava sheets to small and low craters. The features created by a volcano vary depending on the type of eruption, the material erupted and the effects of erosion.

Four types of volcanic landforms are formed:

i. Ash and Cinder Cones or Explosion Cones:

These appear where explosive eruptions take place. When very hot solid fragments from a central crater (or a subsidiary crater) are ejected. A concave cone of height not exceeding 300 m is formed.

ii. Lava Cones:

These are formed from slowly upwelling lava.

These are of two types:

(a) Steep Sided Volcanoes:

These are formed from sticky acid lava which gets hardened quickly. The highly viscous lava which is squeezed out makes spines like tower.

(b) Shield Volcanoes:

These show gently sloping dome features. These are formed from runny lava which flows long distances, before getting hardened.

iii. Composite Cones or Strato-Volcanoes or Strato Cones:

These volcanoes have concave cone shaped sides of alternating ash and lava layers. These are common in most very high volcanoes. In some cases solid lava may plug the main pipe to the crater. Then pent up gases may blast the top off.

When the magma chamber empties, the summit of the volcano collapses. As a consequence, the feature produced is a vast shallow cavity called a Caldera. Strato volcanoes are the accumulated products of many volcanoes. Chemically most of these products are andesite. Some are dacite and a few are basalt and rhyolite. Due to this chemical mix and characteristic interlayering of lava flows, this volcano is called strato volcano.

iv. Shield Volcanoes:

When a volcano vent produces many successive basaltic lava flows stacked one on top of another in eruptive order, the resulting landform is called a shield volcano. A cinder cone and its associated lava flow can be thought of as the initial building blocks of a shield volcano.

A cinder cone is monogenetic because it forms from a single short-lived eruption (of a few years to a decade or two in duration). In contrast, a shield volcano that is an accumulation of the products of many eruptions over a period of say thousands to hundreds of thousands of years is polygenic.

On land these volcanoes have low angle cones. When they form under water they start with a steeper shape because the lava freezes much faster and does not travel far. The shape fattens to the shield form as the cone builds above the sea level.

v. Plateau Basalts or Lava Plains:

These form the bulk of many volcanic fields. These are features which occur where successive flows of basic lava leaks through fissures, over land surface and then cools and hardens forming a blanket-like feature.

The surface appearance of a flow provides information on the composition and temperature of the magma before it solidified. Very hot low viscosity basalt flows far and fast and produces smooth ropy surfaces. Cooler and less-fluid basalt flows form irregular, jagged surfaces littered with blocks.

The lava flows have blanketed to about 2000 m thickness covering 6,50,000 sq.km. in the Indian Deccan Plateau. Such lava flows have also created the U.S. Columbia River Plateau, the Abyssinian Plateau, the Panama Plateau of South America and the Antrim Plateau of Northern Ireland.

Magmas like dacite and rhyolite that have high silica contents are cooler and more viscous than basalt and hence they do not flow far resulting in the features, lobes, pancakes and domes. Domes often plug up the vent from which they issued, sometimes creating catastrophic explosions and may create a crater.

Eroded volcanoes have their importance. They give us a glimpse of the interior plumbing along which the magma rose to the surface. At the end of an eruption, magma solidifies in the conduits along which it had been rising. The rock so formed is more resistant than the shattered rock forming the walls and hence these lava filled conduits are often left behind when the rest of the volcano has been eroded away.

The filling of the central vertical vent is somewhat circular in section and forms a spire called a neck. The filling of cracks along which lava rose forms nearly vertical tabular bodies called dikes. Sometimes magma works its way along cracks that are nearly horizontal, often along bedding planes of sedimentary rocks. This results in the formation of table-like bodies called sills.

Essay # 5 . Major Gases Emitted by Volcanoes :

Volcanic gases present within the magma are released as they reach the earth’s surface, escaping at the major volcanic opening or from fissures and vents along the side of the volcano. The most prevalent gases emitted are steam, carbon dioxide and hydrogen sulphide. Carbon dioxide is an invisible, odourless poisonous gas. The table below shows the gases emitted from volcanoes.

Essay # 6 . Lightning and Whirlwinds :

Lightning flashes accompany most volcanic eruptions, especially those involving dust. The cause of this lightning is believed to be either contact of sea water with magma or generation of static electricity by friction between colliding particles carried in the erupting gases. Lightning is characteristic of vulcanian eruptions and is common during glowing avalanches.

Whirlwinds are seen during many volcanic eruptions. They are seen above hot lavas. Sometimes they form inverted cones extending a little below the eruption cloud. Energy for the whirlwinds might be from the hot gases and lava, high velocity gas jets in the eruption, heat released into the atmosphere during falls of hot tephra or where lava flows into the sea creating steam.

Essay # 7 . Features Produced by the Escape of Gases from Volcanic Lavas :

The gases of volcanic lavas produce several interesting features while they escape. They expand in the lava of the flow and thus cause the formation of Scoriaceous and Pumiceous rocks. By their explosion, they blow the hardened lava above them in the conduit, into bits and thus produce pyroclastic material.

They form clouds above volcanoes, the rain from which assists in the production of mud flows. When the volcano becomes inactive, they escape aiding in the formation of jumaroles, geysers and hot springs. Scoriaceous rocks are extremely porous. They are formed by the expansion of the steam and other gases beneath the hardened crust of a lava. The final escape of the gases from the hardening lava leaves large rounded holes in the rock.

Pumice is a rock also formed by the expansion and escape of gases. In pumice, many of the holes are in the form of long, minute, closed tubes which make the rock so light that it will float on water.

These tubes are formed by the expansive force of large amounts of gases in an extremely viscous lava that cools very rapidly, forming a glassy rock. Pumice is the rock that is usually formed from the lava ejected from explosive volcanoes. It can be blown to kilometres by explosions.

Essay # 8 . Volcanic Products :

Volcanoes give out products in all the states of matter – gases, liquids and solids.

Steam, hydrogen, sulphur and carbon dioxide are discharged as gases by a volcano. The steam let out by a volcano condenses in the air forming clouds which shed heavy rains. Various gases interact and intensify the heat of the erupting lavas. Explosive eruptions cause burning clouds of gas with scraps of glowing lava called nuees ardentes.

The main volcanic product is liquid lava. Sticky acid lava on cooling, solidifies and hardens before flowing long distances. Such lava can also block a vent resulting in pressure build-up which was relieved by an explosion. Basic fluid lava of lesser viscosity flows to great distances before hardening.

Some lava forms are produced by varying conditions as follows. Clinkery block shaped features are produced when gas spurted from sluggish molten rock capped by cooling crust. These are called Aa.

Pahoehoe is a feature which has a wrinkled skin appearance caused by molten lava flowing below it.

Pillow lava is a feature resembling pillows. This feature piles up when fast cooling lava erupts under water.

Products in explosive outbursts are called Pyroclasts. These consist of either fresh material or ejected scraps of old hard lava and other rock. Volcanic bombs include pancake-flat scoria shaped on impacting the ground and spindle bombs which are twisted at ends as they whizzle through the air. Acid lava full of gas formed cavities produces a light volcanic rock.

Pumice which is so light it can float on water. The product Ignimbrite shows welded glassy fragments. Lapilli are hurled out cinder fragments. Vast clouds of dust or very tiny lava particles are called volcanic ash. Volcanic ash mixed with heavy rain creates mudflows.

Sometimes mudflows can bury large areas of land. Powerful explosions can smoother land for many kilometres around with ash and can hurl huge amount of dust into the higher atmosphere. Violent explosions destroy farms and towns, but volcanic ash provides rich soil for crops.

i. Hot springs:

The underground hot rocks heat the spring waters creating hot springs. The hot springs shed minerals dissolved in them resulting in crusts of calcium carbonate and quartz (geyserite).

ii. Smoker:

This is a submarine hot spring at an oceanic spreading ridge. This submarine spring emits sulphides and builds smoky clouds.

iii. Geyser:

Periodically steam and hot water are forced up from a vent by super-heated water in pipe like passage deep down. Famous geysers are present in Iceland and Yellowstone National Park.

iv. Mud volcano:

This is a low mud cone deposited by mud-rich water gushing out of a vent.

v. Solfatara:

This is a volcanic vent which emits steam and sulphurous gas.

vi. Fumarole:

This is a vent which emits steam jets as at Mt. Etna, Sicily and Valley of Ten Thousand smokes in Alaska.

vii. Mofette:

This is a small vent which emits gases including carbon dioxide. These occur in France, Italy and Java.

Various terms used while describing volcanic features are given below:

i. Magma Chamber:

Magma is created below the surface of the earth (at depth of about 60 km) and is held in the magma chamber until sufficient pressure is built-up to push the magma towards the surface.

This is a pipe like passage through which the magma is pushed up from the magma chamber.

This is the outlet end of the pipe. Magma exits out of the vent. If a vent erupts only gases, it is called fumarole.

iv. Crater:

Generally the vent opens out to a depression called crater at the top of the volcano. This is caused due to the collapse of the surface materials.

v. Caldera:

This is a very big crater formed when the top of an entire volcanic hill collapses inward.

When the erupted materials cover the vent, a volcanic dome is created covering the vent. Later as the pressure of gas and magma rises, another eruption occurs shattering the dome.

A mountain-like structure created over thousands of years as the volcanic lava, ash, rock fragments are poured out onto the surface. This feature is called volcanic cone.

viii. Pyroclastic Flow :

A pyroclastic flow (also known as nuee ardentes (French word) is a ground hugging, turbulent avalanche of hot ash. pumice, rock fragments, crystals, glass shards and volcanic gas. These flows can rush down the steep slopes of a volcano at 80 to 160 km/li, burning everything in their path.

Temperatures of these flows can reach over 500°C. A deposit of this mixture is also often referred to as pyroclastic flow. An even more energetic and dilute mixture of searing volcanic gases and rock-fragments is called a pyroclastic surge which can easily ride up and over ridges.

ix. Seamounts :

A spectacular underwater volcanic feature is a huge localized volcano called a seamount. These isolated underwater volcanic mountains rise from 900 m to 3000 m above the ocean floor, but typically are not high enough to poke above the water surface.

Seamounts are present in all the oceans of the world, with the Pacific ocean having the highest concentration. More than 2000 seamounts have been identified in this ocean. The Gulf of Alaska also has many seamounts. The Axial Seamount is an active volcano off the north coast of Oregon (currently rises about 1400 m above the ocean floor, but its peak is still about 1200 m below the water surface.

Essay # 9 . Source of the Explosive Energy :

The energy for the explosive violence comes from the expansion of the volatile constituents present in the magma, the gas content of which determines the degree of commination of the materials and the explosive violence of the eruption.

This energy is expanded in two ways, firstly in the expulsion of the materials into the atmosphere and secondly, due to expansion within the magma leading to the development of vesicles. The most important gas is steam, which may form between 60 to 90 per cent of the total gas content in a lava. Carbon dioxide, nitrogen and sulphur dioxide occur commonly and hydrogen, carbon monoxide, sulphur and chlorine are also present.

Essay # 10 . Classification of Pyroclastics :

Pyroclastics refer to fragmental material erupted by a volcano. The larger fragments consisting of pieces of crystal layers beneath the volcano or of older lavas broken from the walls of the conduit or from the surface of the crater are called blocks.

Volcanic bombs are masses of new lava blown from the crater and solidified during flight, becoming round or spindle shaped as they are hurled through the air. They may range in size from small pellets up to huge masses weighing many kilonewtons.

Sometimes they are still plastic when they strike the surface and are flattened or distorted as they roll down the side of the cone. Another type called bread crust bomb resembles a loaf of bread with large gaping cracks in the crust.

This cracking of the crust results from the continued expansion of the internal gases. Many fragments of lava and scoria solidified in flight drop back into the crater and are intermixed with the fluid lava and are again erupted.

In contrast to bombs, smaller broken fragments are lapilli (from Italian meaning, little stones) about the size of walnuts; then in decreasing size, cinders, ash and dust. The cinders and ash are pulverized lava, broken up by the force of rapidly expanding gases in them or by the grinding together of the fragments in the crater, as they are repeatedly blown out and dropped back into the crater after each explosion.

Pumice is a type of pyroclastic produced by acidic lavas if the gas content is so great as to cause the magma to froth as it rises in the chimney of the volcano. When the expansion occurs the rock from the froth is expelled as pumice. Pumice is of size ranging from the size of a marble to 30 cm or more in diameter. Pumice will float in water due to many air spaces formed by the expanding gases.

Lava fountains in which steam jets blow the lava into the air produce a material known as Pele’s hair which is identical with rock wool which is manufactured by blowing a jet of steam into a stream of molten rock (Rock wool is used for many types of insulation).

Coarse angular fragments become cemented to form a rock called volcanic breccia. The finer material like cinders and ash forms thick deposits which get consolidated through the percolation of ground water and is called tuff. Tuff is a building stone used in the volcanic regions. It is soft and easily quarried and can be shaped and has enough strength to be set into walls with mortar.

i. Agglomerate:

The debris in and around the vent contains the largest ejected masses of lava bombs which are embedded in dust and ash. A deposit of this kind is known as agglomerate. The layers of ash and dust which are formed for some distance around the volcano and which builds its cone, become hardened into rocks which are called tuffs.

Ash includes all materials with size less than 4 mm. It is pulverized lava, in which the fragments are often sharply angular and formed of volcanic glass; these angular and often curved fragments are called shards.

Since the gas content of ash on expulsion is high it has considerable mobility on reaching the surface; it is also hot and plastic, the result of these conditions being that the fragments often become welded together. The finest of ash is so light that wind can transport it for great distances.

The table below sets out a general classification of pyroclastic rocks based on the particle size of the fragments forming the rocks.

The chart in Fig. 15.3 summarizes the names of the common magmas and their associated ranges in silica. A very important property of magma that determines the eruption style and the eventual shape of the volcano it builds, is its resistance to flow, namely its viscosity.

Magma viscosity increases as its silica content increases. Eruptions of highly viscous magmas are violent. The highly viscous rhyolite magma piles up its ticky masses right over its eruptive vent to farm tall steep sided volcanoes.

On the contrary the basaltic magma flows great distances from its eruptive vent to from low, broad volcanic features. Magma in the intermediate viscosity spectrum say the andesite magma tends to form volcanoes of profile shapes between these two extremes.

An additional important ingredient of magma is water. Magmas also contain carbon dioxide and various sulphur-containing gases in solution. These substances are considered volatile since they tend to occur as gases at temperatures and pressures at the surface of the earth.

As basaltic magma changes composition toward rhyolite the volatiles become concentrated in the silica-rich magma. Presence of these volatiles (mainly water) in high concentration produces highly explosive volcanoes. It should be noted that these volatiles are held in magma by confining pressure. Within the earth, the confining pressure is provided by the load of the overlying rocks.

As the magma rises from the mantle to depths about 1.5 km or somewhat less, the rock load is reduced to that extent that the volatiles (mainly water) start to boil. Bubbles rising through highly viscous rhyolitic magma have such difficulty to escape their way, that many carry blobs of magma and fine bits of rock with them and they finally break free and jet violently upward resulting in a violent buoyant eruption column that can rise to kilometres above the earth.

The fine volcanic debris in such a powerful eruption gets dispersed within the upper atmosphere, hide the sunlight affecting the weather. The greater the original gas concentration in a magma and the greater the volume rate of magma leaving the vent, the taller is the eruption column produced.

The gases escaping from magma during eruption mix with the atmosphere and become part of the air humans, animals and plants breath and assimilate. However as magma cools and solidifies to rock during eruption, some of the gas remains trapped in bubbles creating vesicles. Generally all volcanic rocks contain some gas bubbles. A variety of vesicular rhyolite is pumice. Pumice is vesicular to such an extent, it floats in water.

Essay # 15. Classification of Volcanic Activity:

A classification of volcanic activity based on the type of product is shown in Fig. 15.4. The basic subdivision is based on the proportions of the gas, liquid and solid components, which can be represented on a triangular diagram. The four basic triangles represent the domain of four basic kinds of volcanic activity.

Essay # 16. Cone Topped and Flat Topped Volcanoes:

Generally rhyolite volcanoes are flat-topped because rhyolite magma which is extremely viscous, oozes out of the ground, piles up around the vent and then oozes away a bit to form a pancake shape. In contrast basalt volcanoes generally feed lava flows that flow far from the vent, building a cone.

Basaltic tephra (large particles of different size) is a spongy-looking black, rough material of pebble or cobble. Commercially this tephra is known as cinder and is used for gardening and rail-road beds. In some situations basaltic volcanoes develop flat top profile.

Flat topped volcanoes of basalt can form when there is an eruption under a glacier. Instead of getting ejected as tephra to form a cone, it forms a cauldron of lava surrounded by ice and water and eventually solidifying. When the ice melts, a steep-sided, table-shaped mountain known as a tuya remains. Volcanoes of this type are common in Iceland and British Columbia, where volcanoes have repeatedly erupted under glaciers.

Surprisingly, the Pacific ocean is a home to many flat-topped undersea basaltic mountains. These are called seamounts. How these seamounts were formed was a mystery for a long time. Surveying and dredging operations revealed that most seamounts were formerly conical volcanoes projecting above the water.

Geologists found that the conical volcanoes got lowered due to subsidence and the tops of the volcanoes came near the sea water level and the powerful waves mowed them flat. Continued subsidence caused them to drop below the water surface.

Essay # 17. Types of Volcanoes :

There are many types of volcanoes depending on the composition of magma especially on the relative proportion of water and silica contents. If the magma contains little of either of these, it is more liquid and it flows freely forming a shallow rounded hill.

Large water content with little silica permits the vapour to rapidly rise through the molten rock, throwing fountains of fire high into the air. More silica and less water in the magma make the magma more viscous. Such magma flows slowly and builds-up a high dome.

High content of both water and silica create another condition. In such a case the dense silica prevents the water from vaporizing until it is close to the surface and results in a highly explosive way. Such an eruption is called a Vulcan eruption.

Other types of eruption are named after people or regions associated with them. Vesuvian eruption named after Vesuvius is a highly explosive type occurring after a long period of dormancy. This type ejects a huge column of ash and rock to great heights upto 50 km.

A peleean eruption named after the eruption of Mt. Pelee in Martin que in 1902 is a highly violent eruption ejecting a hot cloud of ash mixed with considerable quantity of gas which flows down the sides of the volcano like a liquid. The cloud is termed nuee ardente meaning glowing cloud. Pyroclastic or ash flow refers to a flow of ash, solid rock pieces and gas. Hawaiian eruptions eject fire fountains.

Essay # 18. Violence of Volcanic Eruptions :

Volcanic activity may be classified by its violence, which in turn is generally related to rock type, the course of eruptive activity and the resulting landforms. We may in general distinguish between lava eruptions associated with basic and intermediate magmas and pumice eruptions associated with acid magmas.

The percentage of the fragmentary material in the total volcanic material produced can be used as a measure of explosiveness and if calculated for a volcanic region can be adopted as an Explosion Index (E), useful for comparing one volcanic region with others. Explosion Index for selected volcanic regions by Rittmann (1962) are shown in the table below.

Newhall and Self (1982) proposed a Volcanic Explosivity Index (VEI) which helps to summarize many aspects of eruption and is shown in the table below.

Essay # 19. Famous Volcanoes around the World :

Many volcanoes are present around the world. Some of the largest and well known volcanoes are listed in the table below.

Essay # 20. Volcanic Hazards :

Volcanic eruptions have caused destruction to life and property. In most cases volcanic hazards cannot be controlled, but their impacts can be mitigated by effective prediction methods.

Flows of lava, pyroclastic activity, emissions of gas and volcanic seismicity are major hazards. These are accompanied with movement of magma and eruptive products of the volcano. There are also other secondary effects of the eruptions which may have long term effects.

In most cases volcanoes let out lava which causes property damage rather than injuries or deaths. For instance, in Hawaii lava flows erupted from Kilauea for over a decade and as a consequence, homes, roads, forests, cars and other vehicles were buried in lavas and in some cases were burned by the resulting fires but no lives were lost. Sometimes it has become possible to control or divert the lava flow by constructing retaining walls or by some provision to chill the front of the lava flow with water.

Lava flows move slowly. But the pyroclastic flows move rapidly and these with lateral blasts may kill lives before they can run away. In 1902, on the island of Martinique the most destructive pyroclastic flow of the century occurred resulting in very large number of deaths.

A glowing avalanche rushed out of the flanks of Mount Pelee, running at a speed of over 160 km/h and killed about 29000 people. In A.D. 79 a large number of people of Pompeii and Herculaneum were buried under the hot pyroclastic material erupted by Mount Vesuvius.

The poisonous gas killed many of the victims and their bodies got later buried by pyroclastic material. In 1986, the eruption of the volcano at Lake Nyos, Cameroon killed over 1700 people and over 3000 cattle.

When magma moves towards the surface of the earth rocks may get fractured and this may result in swarms of earthquakes. The turbulent bubbling and boiling of magma below the earth can produce high frequency seismicity called volcanic tremor.

There are also secondary and tertiary hazards connected with volcanic eruptions. A powerful eruption in a coastal setting can cause a displacement of the seafloor leading to a tsunami. Hazardous effects are caused by pyroclastic material after a volcanic eruption has ceased.

Either melt water from snow or rain at the summit of the volcano can mix with the volcanic ash and start a deadly mud flow (called as lahar). Sometimes a volcanic debris avalanche in which various materials like pyroclastic matter, mud, shattered trees etc. is set out causing damage.

Volcanic eruptions produce other effects too. They can permanently change a landscape. They can block river channels causing flooding and diversion of water flow. Mountain terrains can be severely changed.

Volcanic eruptions can change the chemistry of the atmosphere. The effects of eruption on the atmosphere are precipitation of salty toxic or acidic matter. Spectacular sun set, extended period of darkness and stratospheric ozone depletion are all other effects of eruptions. Blockage of solar radiation by fine pyroclastic material can cause global cooling.

Apart from the above negative effects of volcanisms there are a few positive effects too. Periodic volcanic eruptions replenish the mineral contents of soils making it fertile. Geothermal energy is provided by volcanism. Volcanism is also linked with some type of mineral deposits. Magnificent scenery is provided by some volcanoes.

The study of volcanoes has great scientific as well as social interest. Widespread tephra layers inter-bedded with natural and artificial deposits have been used for deciphering and dating glacial and volcanic sequences, geomorphic features and archeological sites.

For example, ash from Mt. St. Helens Volcano in Washington travelled at least 900 km into Alberta. North American Indians fashioned tools and weapons out of volcanic glass, the origin of which is used to trace migratory and trading routes.

Volcanoes are windows through which the scientists look into the interiors of the earth. From volcanoes we learn the composition of the earth at great depths below the surface. We learn about the history of shifting layers of the earth’s crust. We learn about the processes which transform molten material into solid rock.

From the geological historical view point, volcanic activity was crucial in providing to the earth a unique habitat for life. The degassing of molten materials provided water for the oceans and gases for the atmosphere – indeed, the very ingredients for life and its sustenance.

Essay # 21. Volcanoes and Atmospheric Pollution :

During eruptions volcanoes inject solid particles and gases into the atmosphere. Particles may remain in the atmosphere for months to years and rain back on to the earth. Volcanoes also release chlorine and carbon dioxide.

The main products injected into the atmosphere from volcanic eruptions however are volcanic ash particles and small drops of sulphuric acid in the form of a fine spray known as aerosol. Most chlorine released from volcanoes is in the form of hydrochloric acid which is washed out in the troposphere. Volcanoes also emit carbon dioxide.

During the times of giant volcanic eruptions in the past the amount of carbon dioxide released may have been enough to affect the climate. In general global temperatures are cooler for a year or two after a major eruption.

A large magnitude pyroclastic eruption such as a caldera-forming event can be expected to eject huge volumes of fine ash high into the atmosphere where it may remain for several years, carried around the globe by strong air currents in the upper atmosphere.

The presence of this ash will increase the opacity of the atmosphere, that is, it will reduce the amount of sunlight reaching the earth’s surface. Accordingly, the earth’s surface and climate will become cooler. Various other atmospheric effects may be observed. Particularly noticeable is an increase in the intensity of sunsets.

i. Global Warming :

Besides blocking the rays of the sun, the vast clouds of dust and ash that result from a volcanic eruption can also trap ultraviolet radiation within the atmosphere causing global warming.

Volcanic eruptions usually include emissions of gases such as carbon dioxide which can further enhance this warming. Even if it lasted only for a relatively short time, a sudden increase in temperature could in turn have contributed to extinctions by creating an environment unsuitable for many animals.

ii. Geothermal Energy :

Geothermal energy is the heat energy trapped below the surface of the earth. In all volcanic regions, even thousands of years after activity has ceased the magma continues to cool at a slow rate. The temperature increases with depth below the surface of the earth. The average temperature gradient in the outer crust is about 0.56° C per 30 m of depth.

There are regions however, where the temperature gradient may be as much as 100 times the normal. This high heat flow is often sufficient to affect shallow strata containing water. When the water is so heated such surface manifestations like hot springs, fumaroles, geysers and related phenomena often occur.

It may be noted that over 10 per cent of the earth’s surface manifests very high heat flow and the hot springs and related features which are present in such areas have been used throughout the ages, for bathing, laundry and cooking.

In some places elaborate health spas and recreation areas have been developed around the hot-spring areas. The cooling of magma, even though it is relatively close to the surface is such a slow process that probably in terms of human history, it may be considered to supply a source of heat indefinitely.

Temperatures in the earth rise with increasing depth at about 0.56°C per 30 m depth. Thus if a well is drilled at a place where the average surface temperature is say 15.6°C a temperature of 100°C would be expected at about 4500 m depth. Many wells are drilled in excess of 6000 m and temperatures far above the boiling point of water are encountered.

Thermal energy is stored both in the solid rocks and in water and steam filling the pore spaces and fractures. The water and steam serve to transmit the heat from the rocks to a well and then to the surface.

In a geothermal system water also serves as the medium by which heat is transmitted from a deep igneous source to a geothermal reservoir at a depth shallow enough to be tapped by drilling. Geothermal reservoirs are located in the upward flowing part of a water – convective system. Rainwater percolates underground and reaches a depth where it is heated as it comes into contact with the hot rocks.

On getting heated, the water expands and moves upward in a convective system. If this upward movement is unrestricted the water will be dissipated at the surface as hot springs; but if such upward movement is prevented, trapped by an impervious layer the geothermal energy accumulates, and becomes a geothermal reservoir.

Until recently it was believed that the water in a geothermal system was derived mainly from water given off by the cooling of magma below the surface. Later studies have revealed that most of the water is from surface precipitation, with not more than 5 per cent from the cooling magma.

Production of electric power is the most important application of geothermal energy. A geothermal plant can provide a cheap and reliable supply of electrical energy. Geothermal power is nearly pollution free and there is little resource depletion.

Geothermal power is a significant source of electricity in New Zealand and has been furnishing electricity to parts of Italy. Geothermal installations at the Geysers in northern California have a capacity of 550 megawatts, enough to supply the power needs of the city of San Francisco.

Geothermal energy is versatile. It is being used for domestic heating in Italy, New Zealand and Iceland. Over 70 per cent of Iceland’s population live in houses heated by geothermal energy. Geothermal energy is being used for forced raising of vegetables and flowers in green houses in Iceland where the climate is too harsh to support normal growth. It is used for animal husbandry in Hungary and feeding in Iceland.

Geothermal energy can be used for simple heating processes, drying or distillation in every conceivable fashion, refrigeration, tempering in various mining and metal handling operations, sugar processing, production of boric acid, recovery of salts from seawater, pulp and paper production and wood processing.

Geothermal desalinization of sea water holds promise for abundant supply of fresh water. In some areas it is a real alternative to fossil fuels and hydroelectricity and in future may help meet the crisis of our insatiable appetite for energy.

iii. Phenomena Associated with Volcanism :

In some regions of current or past volcanic activity some phenomena related to volcanism are found. Fumaroles, hot springs and geysers are the widely known belonging to this group. During the process of consolidation of molten magma either at the surface or at some depths beneath the surface gaseous emanations may be given off.

These gas vents constitute the fumaroles. The Valley of Ten Thousand Smokes in Alaska is a well-known fumarole and is maintained as a national monument. This group of fumaroles was formed by the eruption of Mount Katmai in 1912. This valley of area of about 130 square kilometres contains thousands of vents discharging steam and gases.

These gases are of varied temperatures and the temperatures vary from that of ordinary steam to superheated steam coming out as dry gas. Many of the gases escaping from the vents may be poisonous, such as hydrogen sulphide and carbon monoxide which are suffocating and may settle at low places in the topography. For example, the fumaroles at the Poison Valley, Java discharge deadly poisonous gases.

Solfataras are fumaroles emitting sulphur gases. At some places, the hydrogen sulphide gases undergo oxidation on exposure to air to form sulphur. The sulphur accumulates in large amount so that the rocks close to the solfataras may contain commercial quantities of sulphur.

Hot springs are also phenomena associated with volcanic activity. Waters from the surface which penetrate into the ground can get heated either by contact with the rocks which are still hot or by gaseous emanations from the volcanic rocks. The water so heated may re-emerge at the surface giving rise to hot springs. In some situations the hot springs may be intermittently eruptive. Such intermittently hot springs are called geysers.

Related Articles:

• Lava: Types and Eruptions | Volcanoes
• Submarine and Sub Glacial Eruptions | Volcanoes

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• Earth Science
• Types Of Volcanoes

Types of Volcanoes

A volcano is a land-form, a mountain, where molten rocks erupt through the surface of the planet. The volcano mountain opens downwards to a pool of molten rocks below the surface of the earth.

When the pressure builds up in the earth’s crust, eruptions occur. Gasses and rock shoot up through the opening and spill over or fill the air with lava fragments. The volcano eruption can cause lateral blasts, hot ash and lava flow, mudslides, and more.

Categories of Volcanoes

Volcanoes are categorised into three main categories:

An active volcano is one which has recently erupted and there is a possibility that it may erupt soon.

A dormant volcano is one that has not erupted in a long time but there is a possibility it can erupt in the future.

An extinct volcano is one which has erupted thousands of years ago and there’s no possibility of an eruption.

Volcanoes are grouped into four types:

• Cinder cones
• Composite volcanoes
• Shield volcanoes
• Lava volcanoes

Cinder Cones

Cinder cones are circular or oval cones made up of small fragments of lava from a single vent that have been blown up. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics that build up around the vent.

Most cinder cones erupt only once. Cinder cones may form as flank vents on larger volcanoes, or occur on their own.

Composite Volcano

Composite volcanoes are steep-sided volcanoes composed of many layers of volcanic rocks, usually made from high-viscosity lava, ash and rock debris. These types of volcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that give rise to the name.

Composite volcanoes are made of cinders, ash, and lava. Cinders and ash pile on top of each other, lava flows on top of the ash, where it cools and hardens, and then the process repeats.

Shield Volcano

Shield volcanoes are volcanoes shaped like a bowl or shield in the middle with long gentle slopes made by basaltic lava flows. These are formed by the eruption of low-viscosity lava that can flow a great distance from a vent.

They generally do not explode catastrophically. Since low-viscosity magma is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland, as well.

Read More: Shield Volcano

Lava domes are formed when erupting lava is too thick to flow and makes a steep-sided mound as the lava piles up near the volcanic vent. They are built by slow eruptions of highly viscous lava.

They are sometimes formed within the crater of a previous volcanic eruption. Like a composite volcano, they can produce violent, explosive eruptions, but their lava generally does not flow far from the originating vent.

Types of Volcanic Eruptions

Types of volcanic eruptions depend on various factors such as the chemistry of magma, temperature, viscosity, volume, presence of groundwater, and water and gas content. Following are the different types of volcanic eruptions:

• Hydrothermal eruption: These eruptions include ash and not magma. They are driven by the heat caused by hydrothermal systems.
• Phreatic eruption: This is driven when the heat of the magma interacts with the water. These eruptions do not include magma and only ash.
• Phreatomagmatic eruption: This eruption takes place when there is an interaction between the newly formed magma and water.
• Strombolian and Hawaiian eruption: Hawaiian eruption has fire fountains while the Strombolian eruption has explosions due to lava fragments.
• Vulcanian eruption: These eruptions last for a short period of time and can reach up to a height of 20 km.
• Subplinian and Phinian eruptions: Subplinian eruptions reach up to 20 km in height, while Plinian eruptions reach up to 20-35 km.

Frequently Asked Questions – FAQs

Where are the most active volcanoes.

The most active volcano in the world is found in the Kilauea volcano in Hawaii. Other most active volcanoes are Etna in Italy and Piton de la Fournaise on La Reunion island.

What are volcanic rocks?

Volcanic rocks are the igneous rocks that are found in volcanic regions. They are fine-grained, glassy textured rocks. These rocks are also vesicular in texture which is in the form of voids that are created by the volatiles that try to escape from the molten lava. The volcanic rocks are named based on their chemical composition. The most common volcanic rock is basalt. The silica content in the basalt rock is very low. Rhyolite is a volcanic rock that has the highest silica content.

What is the relationship between volcanoes and geysers?

The relationship between volcanoes and geysers is that both of them are dependent on the strong heat source which is present in underground. The mechanism of a geyser is based on the surface phenomenon. When the groundwater beneath the shallow surface gets heated up, the surface explodes resulting in the boiling and steaming of the water. These surfaces get refilled again and the cycle continues. The difference between geysers and volcanoes is that geysers usually occur in volcanic regions while volcanoes don’t have geysers around them.

How volcanoes are formed?

When the magma from the earth’s upper mantle erupts upwards, volcanoes are formed. When the volcano erupts there is a formation of lava and ashes. The lava flows down depositing the ashes. This cycle continues making the site bigger and bigger.

What is plate tectonics?

Plate tectonics describes the way in which the continents drift from one another and form a new place. When the plates move, they collide with each other and grind each other. The tectonic movement is related to the earth’s crust and upper mantle. Earthquakes are the result of tectonic movements.

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Anatomy of a volcano.

Introduction

Volcanoes are both the vents where molten rock material and volcanic gases are erupted from within Earth’s interior, and the cones and mountains built up around those vents. But beyond this simple definition, volcanoes are incredibly diverse with some types being very complex. Some volcanoes make up the largest mountains on the planet, while others are small hills that may only be a few hundred feet (meters) tall. Some volcanoes erupt multiple times over periods of hundreds of thousands of years, while others experience a single eruptive episode. Vents, the openings at the surface where volcanic eruptions occur, and conduits, the channelways that lead from the magma reservoir to the vent, are the only features that all volcanoes have. Some types of volcanoes are exclusively made up of deposits of volcanic ash and other types of tephra. Others are nearly wholly made of lava flows. And yet others contain both pyroclastic deposits and lava flows, and possibly also lava domes, lahar, and/or landslide deposits. Depending on how they are grouped or subdivided, there are eight different types of volcanoes based on their size, shape, eruption style and classification, and types (composition) of magma erupted. Three types of volcanoes—cinder cones, composite volcanoes, and shield volcanoes—are the most common and are the best known. But examples of all eight types of volcanoes are found in national parks. This page explores the anatomy (the internal and external structure) of cinder cones, compositive volcanoes, and shield volcanoes, and provides short introductions to the other five types of volcanoes.

Glossary—All Volcanoes

Volcanic edifice, [all terms].

• Conduit  - The channelway or passage, which may be pipe-shaped, that brings magma from the reservoir or chamber to the vent at the surface where it is erupted.
• Magma  - Molten rock beneath Earth’s surface capable of intrusion and extrusion.
• Vent  - The opening or place at Earth’s surface through which magma, rock fragments, and/or  volcanic gases are emitted.
• Volcanic edifice  - A mountain or cone that is the main portion of a volcano. It results from the accumulation of lava, tephra, pyroclastic flows, lahars, and/or other volcanic deposits around a vent or series of vents.
• Volcano  - A vent where molten rock material emerges from the Earth’s interior, and/or the edifice (mountain or cone) built up around that vent or vents during eruption(s).

Cinder Cone Volcanoes

Cinder cones are small volcanoes that consist of volcanic ash, cinders, and other types of tephra that has piled up around a vent. Cinder cones are typically built in a single eruptive period that lasts a few months and that may include the eruption of fluid lava flows from vents located along the base. Cinder cones are usually less than 1,000 feet tall (330 m).

Left image Schematic diagram of a composite volcano. Credit: NPS illustration by Trista Thornberry-Ehrlich (Colorado State University).

Right image Diagram with feature labels. Credit: NPS illustration by Trista Thornberry-Ehrlich (Colorado State University).

Glossary—Cinder Cone Volcanoes

Rafted cinder cone, volcanic bomb.

Ash  - Fine fragments (less than 2–4 mm in diameter) of volcanic rock formed by a volcanic explosion or ejected from a volcanic vent.

Cinder  - A colloquial term for a small nut-size to fist-size, or larger, piece of red or black highly vesicular lava that cooled in air during flight after eruption from a vent. The term is roughly synonymous with scoria.

Conduit  - The channelway or passage, which may be pipe-shaped, that brings magma from a reservoir or chamber to the vent at the surface where it is erupted.

Lava flow  - An outpouring of molten rock from a vent onto Earth's surface during an effusive volcanic eruption; also the resulting solidified body of rock.

Magma  - Molten rock beneath Earth’s surface capable of intrusion and extrusion

Rafted cinder cone  - A hill made up of cinders that is a fragment of a cinder cone that was carried away by a lava flow erupted from a side vent near the base of the cone.

Spatter  - An accumulation of highly molten bombs that landed while still molten and welded together to form solid rock, spatter cones, or sometimes feed lava flows. Spatter is formed from fire fountains. Spatter deposits are typically only formed near a vent.

• Tephra  - A collective term used for all pyroclastic material, regardless of size, shape, or origin, ejected into the air during a volcanic eruption.

Vent  - The opening or place at Earth’s surface through which magma, rock fragments, and/or volcanic gases are emitted.

Volcanic bomb  - A pyroclast with a diameter greater than 64 mm (2.5 inches) with a rounded or ellipsoidal shape that indicates that it was wholly or partially molten during eruption and flight.

Cinder cones are the most common type of volcano in the National Park System. At least 24 units in the National Park System contain cinder cones.

Composite Volcanoes

Composite volcanoes experience many eruptive periods over a long expanse of time (hundreds of thousands of years). These complex volcanoes are made of lava flows, pyroclastic deposits, as well as volcanic domes. Lahars and landslides that reshape these volcanoes may occur during eruptions or at other times. This volcano type is also known as a stratovolcano, but the term "composite volcano" is generally preferred.

Left image Schematic diagram of a composite volcano. Credit: Modified from USGS illustration.

Right image Diagram with feature labels. Credit: Modified from USGS illustration.

Glossary—Composite Volcanoes

Eruption cloud, eruption column, pyroclastic flow.

Ash - Fine fragments (less than 2–4 mm in diameter) of volcanic rock formed by a volcanic explosion or ejected from a volcanic vent.

Conduit - The channel or pipe that carries magma from a reservoir or chamber to the vent where it is erupted.

Eruption cloud - A cloud of volcanic ash, tephra, and gases that forms downwind of an erupting volcano.

Eruption column - A vertical pillar of superheated volcanic ash, tephra, and gases ejected from a volcanic vent during an explosive eruption. Eruption columns usually spread laterally into eruption clouds higher in the atmosphere.

Fumarole - A vent or opening at the surface where volcanic gases and vapors are emitted.

Landslide - A collective term covering a wide variety of slope-movement landforms and processes that involve the downslope transport of soil and rock material en masse under the influence of gravity. On volcanoes, landslides may occur during or soon after volcanic eruptions or at other times.

Lava dome - A steep-sided mass of viscous, commonly blocky, lava extruded from a vent; typically has a rounded top and covers a roughly circular area; may be isolated or associated with lobes or flows of lava from the same vent; typically silicic (rhyolite or dacite) in composition.

Magma - Molten rock beneath Earth’s surface capable of intrusion and extrusion.

Pyroclastic flow -  Pyroclastic flows are hot density currents of pumice, ash, blocks, and volcanic gas that rapidly move down the slopes of a volcano. They may be initiated by collapse of eruptive columns, by explosive eruptions that boil over, and by the collapse of lava domes.

• Vent  - The opening or place at Earth’s surface through which magma, rock fragments, and/or volcanic gases are emitted.

At least eight units of the National Park System contain composite volcanoes.

Shield Volcanoes

Shield volcanoes are almost exclusively made up of fluid lava flows that can travel great distances from their vents. Shields are massive volcanoes with gentle slopes. Eruptions are usually effusive and may occur at the summit area and along fissures located along their flanks. These volcanoes are characterized by numerous lava flows, lava flow fields, as well as surface features of basaltic lava flows. Shield volcanoes experience many eruptions over their lifespans.

Left image Schematic diagram of a shield volcano. Credit: USGS illustration.

Right image Diagram with feature labels. Credit: USGS illustration.

Glossary—Shield Volcanoes

Fire fountain, lava flow field, vog (volcanic smog).

Breakout - A new area or region of a lava flow formed where lava from the molten interior of a previously-formed lobe breaks out through its sides or upper margin to create a distinct lava flow advance.

Fire fountain - A spray of molten lava propelled a few tens to hundreds of feet (meters) into the air by rapid expansion of gas bubbles. They may erupt from vents or form in an active lava lake. Fire fountains most commonly occur in basaltic lavas erupted in Effusive (Hawaiian) eruptions. Also called a lava fountain.

Lava flow - An outpouring of molten rock from a vent onto Earth's surface during an effusive volcanic eruption; also the resulting solidified body of rock.

Lava flow field - A body of lava, consisting of one or more lava flows, that is the product of a single eruption. 

Laze plume - A white cloud of a mixture of condensed seawater steam, hydrochloric acid gas, and shards of volcanic glass produced when lava boils seawater to dryness. Short for “lava haze.”

Lava tube - Conduit through which lava travels beneath the surface of a lava flow; also, a cavernous segment of the conduit that remains after the flow of lava ceases.

Tephra - A collective term used for all pyroclastic material, regardless of size, shape, or origin, ejected into the air during a volcanic eruption.

Vent - The opening or place at Earth’s surface through which magma, rock fragments, and/or  volcanic gases are emitted.

Vog (volcanic smog) - A hazy mixture of sulfur dioxide (SO2) gas and aerosols of sulfuric acid and other sulfates created when volcanic gases interact with oxygen and moisture in the atmosphere and sunlight. Short for “volcanic smog.”

At least 13 units in the National Park System contain shield volcanoes.

Volcanoes of Many Sizes

Volcanoes may be of any size. At the two ends of the size spectrum, cinder cones are typically the size of small hillocks and shield volcanoes may be the most massive mountains on Earth. The difference in size between these two types of volcanoes is so vast that it is difficult to show their relative sizes in a single illustration. Shield volcanoes may be 30 or more times taller than cinder cones, and may have a volume of 25,000 times that of a cinder cone.

NPS illustration by Trista Thornberry-Ehrlich (Colorado State University).

Comparing The Three Classic Types of Volcanoes

Other types of volcanoes.

These volcanoes frequently do not have the classical cone or shield shapes that many people ascribe to volcanic landforms. They include large features that may not at first appear to be a volcano, depressions that may be filled by lakes, and elongated vents where eruptions occur but where volcanic mountains are not constructed. Together, these types are an important part of the diversity of volcanoes. They also share many of the features of the three main types of volcanoes described above.

Calderas are large, roughly circular collapse features that form during voluminous eruptions that partially empty underlying magma chambers. Explosive calderas form during Volcanic Explosivity Index (VEI) 6–8 (Colossal to Apocalyptic) eruptions. Summit calderas form during climatic eruptions of preexisting composite volcanoes and may be more than 10 miles (16 km) in diameter. Resurgent calderas are even larger, with diameters of many tens of miles (kms).

USGS public domain image.

At least eight units of the National Park System contain calderas.

► Volcanic Domes (Lava Domes)

Volcanic domes are steep-sided accumulations of highly viscous lavas that dome up after eruption from a vent instead of flowing laterally to form a lava flow.

At least 12 units of the National Park System contain volcanic domes.

► Fissure Volcanoes

Volcanoes that have an elongated fissure as their vent. Some fissure volcanoes lack substantial edifices as they may erupt fluid lava flows that may travel great distances from the vent.

Graphic by Trista Thornberry-Ehrlich (Colorado State University) after Hughes and others (1999) -- Mafic Volcanism and Environmental Geology of the Eastern Snake River Plain.

At least four units of the National Park System contain fissure volcanoes.

► Maars and tuff rings

Maars and tuff rings form during highly explosive eruptions when hot magma interacts with water. Both types of volcanoes consist of low rings of tephra surrounding a central crater. Maars have craters below the general surface elevation and result from the interaction of magma with shallow groundwater or permafrost. Tuff rings have craters above the surrounding ground surface and form when eruptions encounter surface water or ice.

NPS illustration by Trista L. Thornberry-Ehrlich (Colorado State University).

At least six units of the National Park System contain maars or tuff rings.

► Monogenetic Volcanic Fields

Monogenetic volcanic fields may consist of hundreds of volcanic vents and associated lava flows and form in areas with low magma supply. Individual volcanoes in these fields, whether they are cinder cones, maars, tuff rings, fissure volcanoes or other types, each have their own volcanic plumbing system.

ASTER satellite image draped over USGS topographic data.

At least 13 units of the National Park system contain all or parts of monogenetic volcanic fields.

Educational Slide Set—Volcano Illustrations

Last updated: July 5, 2023

Essay on Volcano

Students are often asked to write an essay on Volcano in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on Volcano

What is a volcano.

A volcano is a crack in the Earth’s surface. Through this crack, melted rock, ash, and gases can escape from deep inside the Earth. Think of it like a soda bottle. If you shake it and then open the top, everything rushes out. That’s similar to what happens during a volcanic eruption.

Types of Volcanoes

There are mainly three types: shield, cone, and composite. Shield volcanoes are broad and flat. Cone volcanoes are steep and pointy. Composite volcanoes are tall and can be very explosive. Each type acts differently when it erupts.

Why Do Volcanoes Erupt?

Deep inside the Earth, it’s so hot that rocks melt into liquid called magma. When magma is lighter than the rock around it, it moves up. If it reaches the Earth’s surface, it erupts. This can happen because of the Earth’s plates moving and creating pressure.

Living with Volcanoes

People live near volcanoes for the fertile soil, which is good for farming. But, living close to a volcano can be dangerous. Scientists help by monitoring volcanoes to predict eruptions and keep people safe.

Also check:

• 10 Lines on Volcano
• Paragraph on Volcano

250 Words Essay on Volcano

A volcano is a crack in the Earth’s surface where molten rock, ash, and gases from deep inside the Earth come out. Think of it like a soda bottle that’s been shaken up. When you open the cap, everything rushes out because of the pressure. In the same way, when a volcano erupts, it releases pressure from beneath the Earth’s crust.

There are different kinds of volcanoes, mainly based on their shape and how often they erupt. Some are called shield volcanoes because they’re broad and low, like a warrior’s shield. Others are called stratovolcanoes, which are tall and steep. They usually have more explosive eruptions. Then there are cinder cone volcanoes, which are smaller and made of bits of rock and ash.

Volcanoes erupt because of the movement of tectonic plates, which are big pieces of the Earth’s surface. When these plates move, they can cause magma from deep inside the Earth to push its way up to the surface. This magma then becomes lava when it comes out of the volcano.

The Impact of Volcanoes

Volcanoes can be dangerous, destroying homes and forests with their lava flows and ash. But they also create new land and bring important nutrients to the soil, which can help plants grow. Plus, the gases they release into the atmosphere can affect the Earth’s climate.

Understanding volcanoes helps us prepare for their eruptions and appreciate the powerful forces that shape our planet.

500 Words Essay on Volcano

Volcanoes: nature’s fiery breath.

Volcanoes are fascinating natural wonders that capture our imaginations. These colossal mountains showcase the immense power of nature, capable of awe-inspiring eruptions and destruction. Let’s explore the world of volcanoes and delve into some of their most intriguing aspects.

A Peek Inside a Volcano

Imagine a giant underground chamber filled with molten rock, known as magma. This magma is incredibly hot, and it’s constantly pushing against the Earth’s crust. When the pressure becomes too intense, it finds a way to escape, and that’s when a volcano erupts.

Types of Volcanic Eruptions

There are various types of volcanic eruptions, each with its own characteristics. Some eruptions are explosive, sending ash and lava soaring high into the air. Others are more gentle, with lava flowing slowly out of the volcano. Some eruptions produce glowing clouds of ash, called pyroclastic flows, which can race down the volcano’s slopes at high speeds.

Volcanic Hazards

While volcanoes can be a sight to behold, they also pose potential hazards. Lava flows can destroy entire villages and forests, and ash clouds can disrupt air travel. Volcanic eruptions can also trigger earthquakes, landslides, and tsunamis.

Predicting Volcanic Eruptions

Scientists are constantly studying volcanoes to better understand their behavior and predict when they might erupt. They use various instruments to monitor seismic activity, gas emissions, and ground deformation. By gathering this data, scientists can often provide warnings before an eruption occurs, giving people time to evacuate.

Volcanoes and the Environment

Volcanic eruptions can have both positive and negative impacts on the environment. On the one hand, they can release harmful gases and ash into the atmosphere, which can affect air quality and climate. On the other hand, volcanic eruptions can create new landforms, provide fertile soil for agriculture, and support unique ecosystems.

Conclusion: The Majestic Force of Nature

Volcanoes are a powerful reminder of the Earth’s dynamic nature. They can be both destructive and awe-inspiring, showcasing the incredible forces that shape our planet. By studying volcanoes, we can better understand the Earth’s processes and prepare for potential hazards, while still appreciating their majestic beauty.

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Essay On The Volcano – 10 Lines, Short & Long Essay For Kids

Key Points To Remember When Writing An Essay On The Volcano For Lower Primary Classes

10 lines on the volcano for kids, a paragraph on the volcano for children, short essay on volcano in 200 words for kids, long essay on volcano for children, interesting facts about volcanoes for children, what will your child learn from this essay.

A volcano is a mountain formed through an opening on the Earth’s surface and pushes out lava and rock fragments through that. It is a conical mass that grows large and is found in different sizes. Volcanoes in Hawaiian islands are more than 4000 meters above sea level, and sometimes the total height of a volcano may exceed 9000 meters, depending on the region it is found. Here you will know and learn how to write an essay on a volcano for classes 1, 2 & 3 kids. We will cover writing tips for your essay on a volcano in English and some fun facts about volcanoes in general.

Volcanoes are formed as a result of natural phenomena on the Earth’s surface. There are several types of volcanoes, and each may emit multiple gases. Below are some key points to remember when writing an essay on a volcano:

• Start with an introduction about how volcanoes are formed. How they impact the Earth, what they produce, and things to watch out for.
• Discuss the different types of volcanoes and talk about the differences between them.
• Cover the consequences when volcanoes erupt and the extent of the damage on Earth.
• Write a conclusion paragraph for your essay and summarise it. 

When writing a few lines on a volcano, it’s crucial to state interesting facts that children will remember. Below are 10 lines on volcanoes for an essay for classes 1 & 2 kids.

• Some volcanoes erupt in explosions, and then some release magma quietly.
• Lava is hot and molten red in colour and cools down to become black in colour. 
• Hot gases trapped inside the Earth are released when a volcano erupts.
• A circle of volcanoes is referred to as the ‘Ring of Fire.’
• Volcano formations are known as seismic activities.
• Active volcanoes are spread all across the earth. 
• Volcanoes can remain inactive for thousands of years and suddenly erupt.
• Most volcanic eruptions occur underwater and result from plates diverging from the margins.
• Volcanic hazards happen in the form of ashes, lava flows, ballistics, etc.
• Volcanic regions have turned into tourist attractions such as the ones in Hawaii.

Volcanoes can be spotted at the meeting points of tectonic plates. Like this, there are tons of interesting facts your kids can learn about volcanoes. Here is a short paragraph on a volcano for children:

A volcano can be defined as an opening in a planet through which lava, gases, and molten rock come out. Earthquake activity around a volcano can give plenty of insight into when it will erupt. The liquid inside a volcano is called magma (lava), which can harden. The Roman word for the volcano is ‘vulcan,’ which means God of Fire. Earth is not the only planet in the solar system with volcanoes; there is one on Mars called the Olympus Mons. There are mainly three types of volcanoes: active, dormant, and extinct. Some eruptions are explosive, and some happen as slow-flowing lava.

Small changes occur in volcanoes, determining if the magma is rising or not flowing enough. One of the common ways to forecast eruptions is by analysing the summit and slopes of these formations. Below is a short essay for classes 1, 2, & 3:

As a student, I have always been curious about volcanoes, and I recently studied a lot about them. Do you know? Krakatoa is a volcano that made an enormous sound when it exploded. Maleo birds seek refuge in the soil found near volcanoes, and they also bury their eggs in these lands as it keeps the eggs warm. Lava salt is a popular condiment used for cooking and extracted from volcanic rocks. And it is famous for its health benefits and is considered superior to other forms of rock or sea salts. Changes in natural gas composition in volcanoes can predict how explosive an eruption can be. A volcano is labelled active if it constantly generates seismic activity and releases magma, and it is considered dormant if it has not exploded for a long time. Gas bubbles can form inside volcanoes and blow up to 1000 times their original size!

Volcanic eruptions can happen through small cracks on the Earth’s surface, fissures, and new landforms. Poisonous gases and debris get mixed with the lava released during these explosions. Here is a long essay for class 3 kids on volcanoes:

Lava can come in different forms, and this is what makes volcanoes unique. Volcanic eruptions can be dangerous and may lead to loss of life, damaging the environment. Lava ejected from a volcano can be fluid, viscous, and may take up different shapes. 

When pressure builds up below the Earth’s crust due to natural gases accumulating, that’s when a volcanic explosion happens. Lava and rocks are shot out from the surface to make room on the seafloor. Volcanic eruptions can lead to landslides, ash formations, and lava flows, called natural disasters. Active volcanoes frequently erupt, while the dormant ones are unpredictable. Thousands of years can pass until dormant volcanoes erupt, making their eruption unpredictable. Extinct volcanoes are those that have never erupted in history.

The Earth is not the only planet in the solar system with volcanoes. Many volcanoes exist on several other planets, such as Mars, Venus, etc. Venus is the one planet with the most volcanoes in our solar system. Extremely high temperatures and pressure cause rocks in the volcano to melt and become liquid. This is referred to as magma, and when magma reaches the Earth’s surface, it gets called lava. On Earth, seafloors and common mountains were born from volcanic eruptions in the past.

What Is A Volcano And How Is It Formed?

A volcano is an opening on the Earth’s crust from where molten lava, rocks, and natural gases come out. It is formed when tectonic plates shift or when the ocean plate sinks. Volcano shapes are formed when molten rock, ash, and lava are released from the Earth’s surface and solidify.

Types Of Volcanoes

Given below various types of volcanoes –

1. Shield Volcano

It has gentle sliding slopes and ejects basaltic lava. These are created by the low-viscosity lava eruption that can reach a great distance from a vent.

2. Composite Volcano (Strato)

A composite volcano can stand thousands of meters tall and feature mudflow and pyroclastic deposits.

3. Caldera Volcano

When a volcano explodes and collapses, a large depression is formed, which is called the Caldera.

4. Cinder Cone Volcano

It’s a steep conical hill formed from hardened lava, tephra, and ash deposits.

Causes Of Volcano Eruptions

Following are the most common causes of volcano eruptions:

1. Shifting Of Tectonic Plates

When tectonic plates slide below one another, water is trapped, and pressure builds up by squeezing the plates. This produces enough heat, and gases rise in the chambers, leading to an explosion from underwater to the surface.

2. Environmental Conditions

Sometimes drastic changes in natural environments can lead to volcanoes becoming active again.

3. Natural Phenomena

We all understand that the Earth’s mantle is very hot. So, the rock present in it melts due to high temperature. This thin lava travels to the crust as it can float easily. As the area’s density is compromised, the magma gets to the surface and explodes.

How Does Volcano Affect Human Life?

Active volcanoes threaten human life since they often erupt and affect the environment. It forces people to migrate far away as the amount of heat and poisonous gases it emits cannot be tolerated by humans.

Here are some interesting facts:

• The lava is extremely hot!
• The liquid inside a volcano is known as magma. The liquid outside is called it is lava.
• The largest volcano in the solar system is found on Mars.
• Mauna Loa in Hawaii is the largest volcano on Earth.
• Volcanoes are found where tectonic plates meet and move.

Your child will learn a lot about how Earth works and why volcanoes are classified as natural disasters, what are their types and how they are formed.

Now that you know enough about volcanoes, you can start writing the essay. For more information on volcanoes, be sure to read and explore more.

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• Volcano Essays

Volcano Essays (Examples)

141+ documents containing “volcano” .

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Volcanoes generally preserved geologic rock record eroded.

Volcanoes generally preserved geologic rock record eroded . However, materials erupted volcanoes found preserved rock record. From learned types volcanoes, infer type volcano erupted an area-based type volcanic deposits found layers rock? Give specific examples, briefly discuss materials linked types volcanoes. Volcanoes are some of the most interesting and at the same time intriguing manifestations of nature. They have been the object of study for decades and all types of technologies were used to either understand the way in which these natural phenomena take place in the sense of eruption or to have a clearer image on the placement in time and geological eras of these structures. Volcanic mountains or constructions usually are formed as a result of constant eruptions and sedimentation of the lava. However, their height or structure is not necessarily a robust one and most often they erode in time, leaving behind only parts of volcanoes or different other….

Hall, C.A. (2007) Introduction to the Geology of Southern California and Its Native Plants. Los Angeles: University of California Press.

Lockwood, J. And Richard W. Hazlett. (2010) Volcanoes: Global Perspectives. West Sussex: Wiley -- Blackwell.

US Department of Interior. (2012) "Volcanoes." U.S. Geological Survey. Available at  http://minerals.cr.usgs.gov/gips/na/process.html 

US Geological Survey. (2011). Principal Types of Volcanoes. Available at  http://pubs.usgs.gov/gip/volc/types.html

Volcanoes Are Often Associated With Fire Earthquakes

Volcanoes are often associated with fire, earthquakes, victims and damage. The activity of nature often turns peaceful mountains with smoky tops into fire vents with lava and smoke getting out and turning everything into fire and burning it. Why do volcanoes erupt and where does such an incredible energy get from inside the earth? After the radioactivity phenomenon was discovered, especially one of uranium and thorium, scientists began to understand that the heat is conserved inside the earth because of the radioactive decay of some chemical elements. The studies made in the field of nuclear energy problems proved this fact again. Accumulation of heat energy inside the earth makes the earth matter heated. The temperature gets so high that the matter has to melt but under the high pressure of the upper earth layers it stays solid. In the places where the pressure of the upper earth layers is not so high (it….

Keys, D., 1999, Catastrophe: A Quest for the Origins of the Modern World, Ballentine Books, New York, 343 pp.

Zeilinga de Boer, J., and D. Sanders, 2002, Volcanoes in Human History: The Far-Reaching Effects of Major Eruptions: Princeton Univ. Press, Princeton and Oxford.

Simkin, T., and L. Siebert, 1994, Volcanoes of the World, Geoscience Press, Inc., Tucson, AZ, p. 68.

The Great Volcanic Explosion of Krakatoa, Article available on web: http://www.drgeorgepc.com/Vocano1883Krakatoa.html

Volcanoes Many People Make the Assumption That

Volcanoes Many people make the assumption that the most severe damage done by volcanoes results from the hot lava that flows from some volcanoes. For example, the lava that flows from Hawaiian volcanoes -- called "Hawaiian volcanism" -- are quite striking and make incredibly beautiful yet dangerous-looking videos and still photos. But that volcanic eruption is not nearly as hazardous as the eruption from a volcano like Mount St. Helens. This paper discusses the most dangerous volcano eruptions, and it also references certain side effects from some volcanoes that most people aren't aware of. Volcanic Hazards hen Mount St. Helens exploded on May 18, 1980, there was no red hot lava flowing down from the top of the mountain. But there was an enormously powerful blast that permanently altered the landscape. This kind of explosive blast from a volcano is considered to be the most violent. An article in Life Science online magazine….

Works Cited

Bagley, M. (2013). Mount St. Helens Eruption: Facts & Information. Live Science. Retrieved December 24, 2013, from  http://www.livescience.com .

N-D-A.org. (2011). Natural Hazards / Volcanoes. Retrieved December 24, 2013, from  http://www.n-d-a.org .

Volcanoes Are One of the

In the United States this strategy is handled by that United States Geographical Survey. The survey has a color coded plan for handling such threats this includes: Green-No immediate threat, Yellow-Watch; Orange- Warning and ed- Eruption in progress. There are certain measures that are taken at each threat level. Conclusion Indeed there are active volcanoes around the world that make many people vulnerable. In most cases scientist can now predict when an eruption may occur with some accuracy. The best protection seems to be early warning. The research also indicates that people should heed such warning if they desire to live. eferences Dormant Volcano Erupts near Manila; Hundreds Feared Dead under Lava. New York Times September 29, 1965. Lahars and Their Effects. United States Geological Survey. 4 April 2007 http://volcanoes.usgs.gov/Hazards/What/Lahars/lahars.html Lava Flows. United States Geological Survey. 4 April 2007 http://volcanoes.usgs.gov/Hazards/What/Lava/lavaflow.html Pyroclastic Flows and Their Effects. United States Geological Survey. April 2007 http://volcanoes.usgs.gov/Hazards/What/PF/pcflows.html Tephra: Volcanic ock and Glass Fragments")." Volcano….

Dormant Volcano Erupts near Manila; Hundreds Feared Dead under Lava. New York Times September 29, 1965.

Lahars and Their Effects. United States Geological Survey. 4 April 2007  http://volcanoes.usgs.gov/Hazards/What/Lahars/lahars.html 

Lava Flows. United States Geological Survey. 4 April 2007  http://volcanoes.usgs.gov/Hazards/What/Lava/lavaflow.html 

Pyroclastic Flows and Their Effects. United States Geological Survey.

Science Volcanoes and Earthquakes Pinatubo

S., with an estimated magnitude of 8.0 on the ichter scale. They formed new lakes, changed the course of the Mississippi iver, and could be felt at least a little in a 50,000 square mile area. In contract, the San Francisco 1906 earthquake could be felt moderately in a 60,000 square mile area, even though it was a smaller quake. Kobe earthquake - Occurred in 1995 and measured 7.3 on the ichter scale. Nearly 6,500 people died in the quake. It caused ten trillion yen in damage, which was 2.5% of Japan's GDP at the time, making it the worst earthquake in Japan since the Great Kanto earthquake in 1923. It is the costliest earthquake in recorded history. Mexico City quake of 1985 - This quake measured 8.1 on the ichter scale, and killed at least 9,000 people, but many Mexico City residents believe the real number was far higher, perhaps as….

Chester, David K. "Volcanoes in Human History." The Geographical Journal 169.4 (2003): 385.

Morton, Ron L. Music of the Earth: Volcanoes, Earthquakes, and Other Geological Wonders. New York: Plenum Press, 1996.

Scarth, Alwyn. Volcanoes: An Introduction. London: UCL Press, 1994.

Malcolm Lowry's Under the Volcano

They still feel the pangs of territorial appropriation, the constraints of being a victim of the colonial project: "You are no a de writer," the Chief responds, "you are de espider, and we shoota de espiders in Mejico" (Lowry 371). Thus, the police in the cafe are not merely symbolic of fascism - they are fascists themselves. The logic of state-based nationalism, as depicted by Lowry in this scene and throughout Under the Volcano, thus serves as a metaphor for the postcolonial desire for states to assert their sovereignty while still under colonial pressure. From a contemporary perspective, one cannot help but consider Under the Volcano from a post-9/11 standpoint. In an era when the borderlands between the United States and Mexico are once again the scene of tremendous controversy, and the American national identity is being asserted in the wake of such threats as terrorism, the threats proffered by….

Arendt, Hannah. The Origins of Totalitarianism. 2nd ed. New York: Harcourt, 1966.

Bhabha, Homi K. The Location of Culture. London: Routledge, 1994.

Lowry, Malcolm. Under the Volcano. New York: Penguin, 1947.

Miller, Andrew John. "Under the nation-state: modernist deterritorialization in Malcolm Lowry's

Eruption of Soufriere Hills Volcano on Island of Montserrat

The area around the volcano has been a hotbed of tectonic activity since it lays near a subduction zone where rock from the Earth's mantle is pushed upward as a reaction to the nearby subduction of the Earth's crust. Since tremendous internal pressures exist due to the displacement of magma below the subduction zone's surface, the Soufriere Hills Volcano sits on top of a giant lava dome that has been holding back high-pressure gasses for years. These gasses, when combined with the rock and magma below the surface, shoot out during an eruption, just as we are currently seeing on the island now and similar to the 1995 eruption. The depth of the magma, which often extends miles below the surface and which is pooled in a magma chamber, can be directly linked to the volcano's surface activity. The eruption has also produced some very familiar side effects associated with….

Disaster Management Options for Volcano

Magma and gasses building up just below the surface before an eruption can cause a bulge many miles in diameter. Since they are so large, these swells cannot be seen by the naked eye (Kerr, 2003). Satellite-borne radars alert volcanologists when such bulges appear. The satellites monitor global positioning (GPS) devices on the ground, using triangulation to mark whether the ground is bulging. Yet, again, the lack of a bulge does not mean that there will not be an eruption so this method is only helpful in some cases and where a volcano is well-monitored (Kerr, 2003). Geochemical monitoring involved watching the changes of gasses associated with volcanic movement. Watching inactive volcanoes for the escape of gasses can be a precursor to eruption (Choi, 2004). Sulfer dioxide, carbon dioxide, and other gasses escaping from the earth signal the movement of magma underground, sometimes meaning that an eruption is imminent (Choi,….

Choi, C. (2004). Volcanic sniffing. Scientific American, 291(5), 22-24.

Kerr, R.A. (2003). High-tech fingers on Earth's erratic pulse. Science, 299(5615), 2016-2019.

Mileti, D.S. (1999). A reassessment of natural hazards in the United States. Washington, D.C.: National Academies Press.

Mount Rainier Washington Is One

ac.wwu.edu/~bgoebel/members/bbarcott.htm>. "Historical Notes - Vancouver's Voyage." 7-14 December 1929. Mount ainier Nature Notes. . "Mount ainier Volcanic Hazards eponse Plan." July 2009. . Parchman, F. "The Super Flood." 19 October 2005. Seattle Weekly. . Service, U.S. Forest. "Eruption: May 18, 1980." January 2010. Mount Saint Helen's National Volcanic Monument. . Signani, L. "The Height of Accuracy." 19 July 2000. Point of Beginning. . U.S. Geodynamics Committee and the National esearch Council. Mount ainier: Active Cascade Volcano. Washington, DC: National Academies Press, 1994. University, Dept. Of Geological Sciences - San Diego State. "Stratovolcanoes." January 2004. How Volcanoes Work. . Watson, J. "Principal Types of Volcanoes." 6 Feburary 1997. United States Geological Survey. . Wood and Kienle, eds. Volcanoes of North America. Cambridge: Cambridge University Press, 1992. "World Top 50 Mountains By Prominance." January 2009. Peakbagger.com. . Zimbelman, ye and Landis. "Fumeroles in Ice Caves on the Summit of Mount ainier." Journal of Volcanology and Geothermal esearch 97.1-4 (2000): 457-73. Seattle Mount ainier.

"Comprehensive Emergency Management Plan." August 2006. Pierce County Washington. .

Driedger, C. "Glacier Flow - Mount Rainier." January 1993. U.S. Geological Survey. .

Drieger and Scott. "Mount Rainier - Living Safeluy With a Volcano in the Backyard." 2008. Cascades Volcano Observatory - USGS. .

Duncan and Burns. The National Parks: America's Best Idea. New York: Knopf, 2009.

Plate Movements and Past Climatic

This happens as the magma chamber empties and a ring fracture occurs. This collapse often blocks the flow of magma but the heated interior still produces gasses and steam. Often, that steam and other gasses create a lake in the middle of the caldera similar to Crater Lake in Oregon or Glen Coe in Scotland. 8. WHY DO SOME VOLCANOES EXPLODE, WHILE OTHERS EMIT ONLY GASEOUS CLOUDS? Some volcanoes explode because the magma that is beneath them is physically forced out of the volcano and into the air. Also, some volcanoes have a core or cap that was formed long ago that holds magma back until it can reach a pressure high enough for it to explode outward. Other volcanoes release only gas because there are pockets of gas and ash trapped above the magma chamber, but below the surface of the volcano. This is released instead of magma and the….

Landforms Barrier Island Beaches Generally Develop Where

LANDFORMS Barrier island beaches generally develop where: a The coast is composed of hard rock b the nearby land has a rugged topography of hills and mountains c the sea floor deepens rapidly offshore d The sea floor remains shallow for a long distance offshore During storms in winter: a There is a higher percentage of fine-grained sand on beaches b More erosion occurs in bays than on headlands c Beaches are eroded d Beaches are built up e Offshore sand bars are destroyed Along the Midocean ridge a earthquakes occur b sea floor spreading occurs c volcanism occurs d all the above occur Where would you find examples of barrier island coasts? a Oregon b California c British Columbia and Alaska d Texas and the Gulf Coast e Hawaii Which of the following boundaries characterize the San Andreas Fault? a Spreading b Convergent c Transform d None of the above Construction of dams upstream on rivers may lead to: a Narrower beaches b Wider beaches c The filling in of….

New Madrid Fault in the Wake of

New Madrid Fault In the wake of recent seismic activity and devastating earthquakes many people tend to speculate as to where the next big earthquake will occur. Most people point to the west coast of the United States as the obvious choice for an earthquake setting. In doing so we ignore a potentially catastrophic area of seismic activity known as the New Madrid Fault, which is Located in New Madrid, Missouri. Despite its potentially dangerous characteristics this area is often overlooked or dismissed due to its mid-western location. It is however, important to note that big earthquakes have occurred in this area and that as time passes the likelihood of a large earthquake occurring in the New Madrid Fault increases. The New Madrid Fault has caused several large earthquakes, the most significant quakes occurred during the years 1811-1812. According to historical accounts which are based on topographic results and effects the….

"Global Volcanism Program | Volcanic Activity Reports | Smithsonian / USGS Weekly Volcanic Activity Report | ." Smithsonian Institution - Global Volcanism Program: Worldwide Holocene Volcano and Eruption Information. N.p., n.d. Web. 23 Apr. 2011. .

"The Virtual Times: The New Madrid Earthquake." THE VIRTUAL TIMES . N.p., n.d. Web. 23 Apr. 2011. .

riverbed., seismically-induced ground motions deforming the. "Historic Earthquakes." U.S. Geological Survey Earthquake Hazards Program. N.p., n.d. Web. 23 Apr. 2011. .

Generational Differences in Volcanic Activity

Hawaiian Volcanoes and Relationship to a Deep-Mantle Plume From the many topics that were given as options by the facilitator of this class, the author of this report has chosen to write about Hawaiian volcanoes and their relationship to the deep-mantle plumes that are nearby and close to them. The area that has come to be known as Hawaii exists within a hotbed of volcanic activity. Of course, this is true both above ground and below it as well. Volcanos play a huge part in how the earth has taken on its current shape as many islands and even many continents have been greatly impacted or formed by the activity of volcanoes. hile the topic of this report makes it very clear that the deep-mantle plume and Hawaiian volcanoes are very heavily linked and this report will explore this in great detail using the suggested resources. Analysis The deep-mantle plume activity around the….

Foulger, Gillian R., and Don L. Anderson. "The Emperor and Hawaiian Volconaic Chains." The Emperor and Hawaiian Chains. N.p., 11 Mar. 2006. Web. 10 Mar. 2016.

Mastin, Larry G., Robert L. Christiansen, Donald A. Swanson, Peter H. Stauffer, and James W. Hendley, II. "Explosive Eruptions at Kilauea Volcano, Hawai'i? Fact Sheet 132-98." Explosive Eruptions at Kilauea Volcano, Hawai'i? Fact Sheet 132-98. N.p., 14 Oct. 2004. Web. 10 Mar. 2016.

NPS. "Frequently Asked Questions: Volcano - Yellowstone National Park (U.S. National Park

Service)." Nps.gov. N.p., 2016. Web. 20 Apr. 2016.

Volcanic Activity and the Consequent

On Dec 16, 1999, in the Corre Grande region of Venezuela, there was simultaneous debris discharge in 20 streams over a distance of 50 Kms. The damage was so profound that it destroyed 25,000 houses and damaged more than 65,000 houses. The total loss was estimated at $2billion U.S. dollars. In view of the largescale damage and loss inflicted by this natural calamity the Venezuelan government decided to collaborate with Chinese researchers in designing an appropriate debris hazard control mechanism. Such debris flow events following the sudden eruption of a dormant volcano is an event of common occurrence in many regions across the world. For example the May 27, 1984 debris flow totally destroyed the copper mining fields in the Yunnan province of China. Similarly, the debris flow along with the water from the melted ice (due to sudden volcanic eruption) completely inundated the town of Armero in Colombia killing….

Bibliography

Wang Shige, "Characteristics of Large Low-frequency Debris Flow Hazards and Mitigation Strategies," Journal of Mountain Science Vol 2 No 1 (2005): 50~58,

Available online at, http://www.imde.ac.cn/journal/Vol_04/p50-58.pdf

Ronald W. Perry, John David Godchaux, 'Volcano hazard management strategies',

Journal of Disaster Prevention and Management, Apr 2005 Volume: 14 Issue: 2-Page: 183-195

Designer Dress

Dress Review: David Tlale David Tlale's orange chiffon dress with gold coins seems to achieve the impossible: it is form-fitting yet fluid. The top is a charcoal and gold-colored metallic jacquard sheath, while orange, Grecian-style drapery flows organically from the models' shoulders to her ankles. Bright coins adorn the front. According to Tlale, the coins are real and were custom-minted with his name and year on it, exhibiting an attention to detail that is typical of the meticulous, yet passionate designer's fashions. The dress was part of Tlale's Climate Change Couture Collection which launched during Africa Fashion Week at the South African Mint factory in 2011. The vision for the dress began when Tlale was approached by the South Africa Mint to collaborate on an environmental awareness campaign. The Mint developed the coins and medallions minted with Tlale's name on it in his honor. Tlale is the first fashion designer in South….

I\'ve seen the common essay topics on mount saint helen. Any lesser-known but interesting ones you can recommend?

1. The impact of Mount St. Helens eruption on local flora and fauna: Explore how the eruption affected the ecosystem and biodiversity of the surrounding area. 2. The role of indigenous peoples in understanding and interpreting natural disasters like the Mount St. Helens eruption: Discuss how indigenous knowledge and traditions can provide valuable insights into the significance of such events. 3. The cultural and social implications of the Mount St. Helens eruption on local communities: Investigate how the eruption impacted the lives, beliefs, and traditions of the people living in the region. 4. The long-term environmental and geological effects of the Mount St.....

Volcanoes generally preserved geologic rock record eroded . However, materials erupted volcanoes found preserved rock record. From learned types volcanoes, infer type volcano erupted an area-based type volcanic deposits…

Volcanoes are often associated with fire, earthquakes, victims and damage. The activity of nature often turns peaceful mountains with smoky tops into fire vents with lava and smoke getting…

Volcanoes Many people make the assumption that the most severe damage done by volcanoes results from the hot lava that flows from some volcanoes. For example, the lava that flows…

In the United States this strategy is handled by that United States Geographical Survey. The survey has a color coded plan for handling such threats this includes: Green-No…

S., with an estimated magnitude of 8.0 on the ichter scale. They formed new lakes, changed the course of the Mississippi iver, and could be felt at least a…

They still feel the pangs of territorial appropriation, the constraints of being a victim of the colonial project: "You are no a de writer," the Chief responds, "you…

The area around the volcano has been a hotbed of tectonic activity since it lays near a subduction zone where rock from the Earth's mantle is pushed upward…

Magma and gasses building up just below the surface before an eruption can cause a bulge many miles in diameter. Since they are so large, these swells cannot…

Research Paper

ac.wwu.edu/~bgoebel/members/bbarcott.htm>. "Historical Notes - Vancouver's Voyage." 7-14 December 1929. Mount ainier Nature Notes. . "Mount ainier Volcanic Hazards eponse Plan." July 2009. . Parchman, F. "The Super Flood." 19 October 2005. Seattle…

Book Review

This happens as the magma chamber empties and a ring fracture occurs. This collapse often blocks the flow of magma but the heated interior still produces gasses and…

Business - Consumer Behavior

LANDFORMS Barrier island beaches generally develop where: a The coast is composed of hard rock b the nearby land has a rugged topography of hills and mountains c the sea floor…

New Madrid Fault In the wake of recent seismic activity and devastating earthquakes many people tend to speculate as to where the next big earthquake will occur. Most people point…

Hawaiian Volcanoes and Relationship to a Deep-Mantle Plume From the many topics that were given as options by the facilitator of this class, the author of this report has chosen…

On Dec 16, 1999, in the Corre Grande region of Venezuela, there was simultaneous debris discharge in 20 streams over a distance of 50 Kms. The damage was so…

Business - Miscellaneous

Dress Review: David Tlale David Tlale's orange chiffon dress with gold coins seems to achieve the impossible: it is form-fitting yet fluid. The top is a charcoal and gold-colored metallic…

GE Volcanoes 2024

Rowan College, Burlington County *

Apr 3, 2024

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