(
Short (single eruption of a few months)
Composite Volcano
Large
(usually between 6,500 and 20,000 ft; 2,000-3,000 m tall)
Long (hundreds of thousands of years)
Shield Volcano
Very large
(up to a maximum of 33,000 ft; 10,000 m tall)
Very long
(up to a million years or longer)
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 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.
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 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 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.
Last updated: July 5, 2023
A volcano is an opening in Earth ’s crust. When a volcano erupts, hot gases and melted rock from deep within Earth find their way up to the surface. This material may flow slowly out of a fissure, or crack, in the ground, or it may explode suddenly into the air. Volcanic eruptions may be very destructive. But they also create new landforms. There are more than 1,500 potentially active volcanoes in the world today.
Strong volcanic eruptions throw bits of magma into the air. These bits cool into tiny pieces of rock, called volcanic dust or volcanic ash. Wind can carry volcanic dust thousands of miles away. Volcanic ash can coat the land for miles around the volcano.
Some of the most violent eruptions take place where the edge of one plate is forced beneath the edge of another. This forces magma to rise to the surface. Hot gases in the magma make these volcanoes very explosive. Most volcanoes of this type are found around the edges of the Pacific Ocean . This huge circle of volcanoes is known as the Ring of Fire .
A small number of volcanoes are not located along the edges of plates. They form at “hot spots” in Earth’s crust. At a hot spot, molten rock rises from deep below the crust. The volcanoes of Hawaii are the best examples of hot-spot volcanoes.
Stratovolcanoes, also called composite volcanoes, are mountains shaped like cones. They have a narrow top with steep sides and a wide bottom. A crater, or bowl-shaped pit, usually lies at the top. Stratovolcanoes are made up of layers of hardened lava and ash. Thousands of eruptions left these layers over millions of years. Mount Fuji in Japan is a stratovolcano.
Shield volcanoes are dome-shaped mountains built by lava flows. They are not as steep as stratovolcanoes, though they can be quite large. Some shield volcanoes that erupt under the sea grow high enough to create islands. The volcanoes of Hawaii are shield volcanoes.
A complex volcano has more than one vent. A volcano can have more than one vent when two cones overlap one another. Or a volcano can form new vents during an explosion.
The effects of volcanoes are not entirely harmful. Volcanic ash soil—called andisol—is good for growing crops. In addition, the volcanic glass called obsidian has been used by many of the world’s peoples for weapons, tools, and ornaments. People also use the volcanic stone called pumice for cleaning wood, metal, and other surfaces and in producing building materials.
The heat within Earth that is released in volcanoes is an enormous potential source of energy . This energy, called geothermal energy, is difficult for people to control. However, hot water and steam trapped below the surface have been used to heat homes and greenhouses and to produce electric power in several countries, including Italy , New Zealand , Japan, Iceland, and the United States.
The word volcano comes from the name of Vulcan , the ancient Roman god of fire and metalworking . The Romans believed that volcanic eruptions resulted when Vulcan made thunderbolts and weapons for the gods. Other cultures explained volcanoes as outbursts of anger from a god or goddess. Pele was the name of the volcano goddess of the native Hawaiians.
Volcanoes have a long history of destruction. In 79 ce the eruption of Mount Vesuvius destroyed the Roman cities of Pompeii and Herculaneum.
Two of the deadliest volcanic eruptions happened on islands in what is now Indonesia . There was the 1815 Mount Tambora eruption and one in 1883. In 1883 the volcano Krakatoa exploded and collapsed, triggering a colossal sea wave known as a tsunami . Tens of thousands of people were killed by these events.
On May 8, 1902, Mount Pelée erupted on the Caribbean island of Martinique . Although very little lava flowed, an unstoppable black cloud of hot gases and ash engulfed the city of Saint-Pierre, killing almost all of its 30,000 people. The birth of a volcano was witnessed between 1943 and 1952, when a smoking hole in a Mexican farmer’s cornfield erupted into a new mountain called Paricutín that eventually stood 1,400 feet (425 meters) above the level ground around it.
Another notable event took place in 1963, when a new volcanic island called Surtsey rose up from the Atlantic Ocean near Iceland. Within a few years it built up to an area of 1 square mile (2.5 square kilometers), with a peak more than 560 feet (170 meters) above sea level.
The 1980 eruption of Mount Saint Helens, in the U.S. state of Washington , was one of the biggest in North America. The 1991 eruption of Mount Pinatubo, in the Philippines , was the largest of the 1900s. These eruptions killed fewer people than earlier volcanoes, but they still destroyed much property.
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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…
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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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Fountains of lava, whiffs of toxic gases, acidic plumes of vaporized seawater and blankets of ash: Those are just a few of the dangers that volcanoes have delivered in recent weeks, with Guatemala’s Fuego Volcano and Hawaii’s Kilauea Volcano each producing its most powerful eruption in decades.
Volcán de Fuego, or Fuego Volcano, in Guatemala erupts. Unlike Hawaiian volcanoes, eruptions in the Americas tend to produce dense clouds of ash, dust, rubble, and angular blocks that rumble down high, steep slopes. (Image credit: Shutterstock)
Dozens of people have died and thousands more have been evacuated in the area around Fuego as a result of its June 3 eruption. Like Kilauea, which in early May 2018 began a violent episode in an eruption that has carried on for nearly 35 years , Fuego was hardly at rest before this latest explosion. It often spews lava and ash several times in a year and can have many small eruptions in a single day.
But this time the Fuego eruption was different. Damage came fast and forcefully in a chaotic mixture of rock, gas and ash known as a pyroclastic flow – creating scenes of destruction bearing little resemblance to the images of creeping lava that have emerged from Kilauea. The contrast offers a reminder that the ways in which volcanoes become dangerous can be as varied as the places and communities where they rumble to life.
Stanford University geologists Gail Mahood (emerita) and Don Lowe, professors of geological sciences in the School of Earth, Energy & Environmental Sciences , have both studied volcanoes up close. They discussed surprising mysteries that remain for scientists around volcanic hazards, what and how researchers can learn from Fuego and other volcanoes after the ash settles and some of the science behind volcanic threats.
What differences caused Fuego to erupt so violently compared to Kilauea?
Don Lowe: We’ve just seen in Guatemala this small town buried in hot ash. Eruptions in the Americas tend to produce enormous amounts of ash, dust, rubble and angular blocks, and the volcanoes often have high, steep cones. Dense clouds of hot ash and rubble rumble down those slopes like freight trains and just gain momentum as they go. Rain and storms can mobilize loose rubble on these steep slopes and create cold debris flows. Hawaiian volcanoes tend to erupt less violent rivers and fountains of lava.
Gail Mahood: All volcanoes in Central America and in the Cascades in North America are different from Hawaii in that they are related to subduction zones, places where one plate squeezes under another. They are much more explosive partly because magmas they erupt have more water dissolved in them – up to 10 times as much as in Hawaiian volcanoes.
Think of magma like a bottle of champagne. When you pop the top, you lower the pressure and that CO 2 gas that was dissolved in the champagne forms bubbles and comes out.
Water, CO 2 , sulfur gases, fluorine and chlorine are dissolved in magma when it is stored at high pressure deep in the Earth. But if magma rises quickly, those volatile elements come out of solution in bubbles that grow so fast the bubble walls break. It’s like a magma foam breaking into pieces and just flying apart.
Magmas in Hawaii might have water making up only half of a percent by weight. If you have 4 or 6 percent water in a magma as we see in Central America, you have that much greater potential for explosive eruptions.
Volcanoes in subduction zones also have more viscous, stickier magmas, which provide more resistance as the bubbles grow. As a result, pressures inside the bubbles can get much higher. So there are more bubbles breaking because of more water, and when the bubbles finally do break, they do so with greater force.
How do pyroclastic flows form after the eruption of a volcano like Fuego in Guatemala?
Mahood : These can form directly from an explosive eruption, or they can form by lava that comes out and cools a little bit, gets stuck and fills the vent. Then maybe there’s an earthquake, or new magma pushes it from below, and that lava plugging the vent comes out in a cascade of hot blocks. Those continue to effervesce and produce ash. People around Fuego are largely being killed by pyroclastic flows.
You’ve studied how volcanoes can trigger dangerous flows of not only lava and ash, but also thick, viscous mixtures of particles and water known as debris flows. Can you describe an example of how this type of flow begins, and what can be done to minimize harm once it’s underway?
Lowe: In 1985, debris flows following the eruption of Nevado del Ruiz volcano in Colombia killed about 20,000 people in a town called Armero, 60 kilometers (37 miles) downslope. These flows originated when hot ash, like the stuff coming out of Fuego, landed on a glacier around the summit. A minor puff of ash melted just a small part of that glacier and sent huge volumes of water cascading down canyons.
We learned by looking at older deposits in roadcuts around this town that this had been a common process in the past. All the elements were there that should have made a planner recognize that this was not a good place for a town. Better geological studies would have shown that the area had suffered many similar catastrophes in the past. In fact, hazard maps created in the months before the eruption showed Armero would be in the path of any mudflows (a type of debris flow) triggered by the volcano. But those maps were not widely distributed.
We still don’t fully understand how debris flows work or how some of them can travel so far over very low slopes. One promising theory is that water gets sucked under the main flow like hydroplaning on your tires. Another theory centers on how particles interact in the flow. Do they just kind of carry along passively in the fluid? Maybe particles in a debris flow behave like gas molecules in a balloon – they collide with one another, exert pressures and help keep themselves suspended.
These details are important to understanding how far debris flows can go, how much stuff they can carry, how quickly they form – all of which are relevant to whether you build towns around volcanoes, deciding how far away they need to be and evaluating the danger of settlements and villages that are already there.
Disaster officials in Guatemala have said Fuego’s June 3 eruption affected more than 1 million people. How does this compare to some of the biggest eruptions in history?
Mahood: This is not a big eruption by any stretch of the imagination. One of the big problems in Guatemala and many other places – in Indonesia and the Philippines, for example – is the large population packed on and around volcanoes of this type. Moderately small eruptions can kill a lot of people.
Fuego is a very active volcano. Presumably, what’s happening this time is it’s been a little more explosive than typical, so these pyroclastic flows are making their way farther down the volcano. Instead of going down the flanks of the pointy, conical volcano and kind of petering out, they’re getting out into the flanks and spilling out into villages.
Is it possible to anticipate whether and when a given eruption will produce this type of hazard?
Mahood: We can often predict that there’s an eruption coming. What’s harder to predict is the exact nature of the eruption and the time of onset.
To map volcanic hazards, volcanologists go into the field and map the footprints of an eruption: ash that fell from high in the air, deposits from pyroclastic and debris flows, and lava. Ash can cover tens of thousands of square miles, but the particles are cold by the time they land so they are catastrophic only close to the vent of the volcano, where they can be thick enough to collapse roofs.
Back in the lab, we use carbon or argon dating to learn about how frequent each type of eruption has been in the past. Increasingly, we’re also analyzing crystals that grew in the magma before an eruption. They act as tiny recorders of temperature, pressure and gas content, so they can help us reconstruct the ascent of the magma and its storage conditions.
Best of all is if these analyses can be integrated with geophysical studies of seismicity or deformation around the volcano. Fuego is difficult to observe because it is heavily forested, and once you get to the top it’s covered in clouds. Geophysicists have gotten very good at predicting eruptions at Kilauea in Hawaii and Mount St. Helens in Washington, because they have watched so many eruptions. We know very well the signs that magma is moving through the crust at Kilauea: The summit deflates and earthquakes change in style in a particular way. The only thing that is not certain is when an eruption like the ongoing one at Kilauea is going to stop.
Is there any way to adapt to threats from volcanic eruptions?
Lowe: We’ve settled areas without much concern about natural disasters and dangers. However, once a disaster occurs, we need to try to limit future growth in that area and in places that face similar risks. We may not see a truly catastrophic eruption in our lifetimes. But in our children’s or grandchildren’s lifetimes, there will inevitably be eruptions that wipe out major population centers. We need to realize how important it is to look further in the future than just tomorrow.
Donald Lowe is also the Max Steineke Professor in the School of Earth, Energy & Environmental Sciences.
Josie Garthwaite, School of Earth, Energy & Environmental Sciences: (650) 497-0947, [email protected]
Donald Lowe, School of Earth, Energy & Environmental Sciences: (650) 725-3040, [email protected]
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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.
Hawaii - A Volcano in the Sea. All the volcanoes in Hawaii are shield volcanoes. They are large and have shallow-sloping sides - almost like a warrior's shield. We will write a custom essay specifically for you by our professional experts. 187 writers online.
Volcanoes in subduction zones also have more viscous, stickier magmas, which provide more resistance as the bubbles grow. As a result, pressures inside the bubbles can get much higher. So there ...
Short Essay on Volcanoes - Free download as PDF File (.pdf), Text File (.txt) or read online for free. The document is a short essay on volcanoes that provides information about their formation, types, and effects. It discusses how volcanoes form from magma rising up from below the Earth's surface. It classifies volcanoes as active, dormant, or extinct based on their level of activity.