A world on fire


Well, a volcano website wouldn't be complete without a facts page would it? So here's a quick guide to volcanoes for those of you who want to know a bit about them.

Volcano Types


These are the typical shapes of volcanoes with steep sides made up of layers of lava, tephra, pyroclastic flows, and lahars. Examples of a stratovolcano are: Fuji, Merapi, and Popocatepetl.

Shield Volcano

So called because they are shaped like a warrior's shield. They have gentle smooth slopes which were built up by layers of liquid basaltic lava. Examples of a shield volcano are: Mauna Loa, Kilauea, and Piton de la Fournaise.

Complex Volcano

Large volcanic structures which consist of multiple lava domes or stratovolcanoes formed at different times. Examples of a complex volcano are: Pacaya and Dukono.

Compound Volcano

A volcanic structure with multiple vents confined within a small area as a result of vent migration. Example of a Compound Volcano: Zhupanovsky

Cinder Cone

These aren't very large volcanoes but they're made up of layers of lava and scoria emitted by strombolian eruptions. It is common to find them as vents on major volcanoes as well as individually, and are usually typically black in colour. Examples of cinder cones are: Paricutin and Cerro Negro. 

Pyroclastic Cone

These can be very similar to Cinder Cones and they are either found as vents on volcanoes, or individually. They're made up of layers of fine particles and volcanic bombs. Typically grey in colour. Examples of a Pyroclastic Cone are: Carran-los Venados and the Tavurvur cone in the Rabaul Caldera.

Lava Dome

Steep sided dome shaped mounds made out of slow moving viscous lava which forms over a vent and hardly flows far. These are notorious for causing major explosive eruptions or pyroclastic flows. Examples of lava domes are: Mount St. Helens, Soufriere Hills, and Santiaguito.


Calderas are huge craters usually formed by a collapsed volcano or the collapse of the roof of a magma chamber. Examples of a caldera are: Masaya, Santorini, and Krakatau. 

Somma Volcano

A partially filled caldera with a newer central cone in it. Example of a somma volcano: Ebeko.

Tuff Cone

Similar to a cinder cone except they are less common and are formed by explosions when magma comes into contact with water. Example of a tuff cone: Surtsey.

Fissue Vents

These are just basically cracks in the ground which are caused by the upwelling of magma in the earth's crust which then erupts volcanic material. These are commonly found at continental rift zones/mid ocean ridge zones as well as on the flanks of volcanoes. Examples of fissue vent volcanoes are: Ardoukoba and Laki.

Sub Glacial Volcano

Volcanoes which are under the ice. When a volcanic activity occurs, the ice melts giving way to surtseyan explosions of when magma comes into contact with meltwater. An example of a sub-glacial volcano is: Grimsvotn.

Submarine Volcano

There are many of these around the oceans of the world. Because they are so deep under the sea level, the pressure of the deep water limits their eruption force. They will produce pillow lavas unless they are on subduction zones. They can also come in the form of an underwater fumerole called a "Black Smoker". Examples of submarine volcanoes: Kick-Em-Jenny and Bayonnaise Rocks.

Eruption Types


These types of eruptions usually occur at hotpot volcanoes such as in Hawaii, Reunion Island, Iceland, or the Galapagos Islands. They typically occur when liquid basaltic magma erupts as lava fountains which are known to spurt hundreds of metres high into the air or as lava lakes which can fill a crater.


These are produced by medium-low magma and occur when gas bubbles build up in the magma chamber then cause explosions of incandescent material into the air (One after another) when the bubbles rise and come into contact with the more cooler viscous lava on the surface.


Caused by explosions of large amounts of gas through viscous magma. This type of eruption is known to eject ash, gas, and lava bombs at considerable distances.


This is the most violent and largest eruption which is caused by viscous magma rich in gas. A tall eruption column is produced as a result of a powerful explosion of ash, gas, and other material being ejected high up into the atmosphere.


These involve lava domes more than the volcano itself. Lava domes are known to have steep sides and grow vertically making the lava dome subject to collapse. When a lava dome explodes or collapses, huge chunks of incandescent material rolls down the slopes at roaring speeds causing nuee ardentes or pyroclastic flows which devastate anything in their path.


These are caused when water interacts with magma producing explosions of fine grained tephra. Explosions look like tails of thick dirt mixed with ash and steam. Surtsey volcano off coast of Iceland when it was in it's early stages is a prime example of this.


These are steam eruptions without any magmatic ejections which are usually caused when groundwater over vents are rapidly heated by the magma underground. Although not major, phreatic eruptions are very common among most volcanoes. Sometimes in some cases, they are a sign that dormant volcanoes are about to come back to life.


Caused by interactions of magma coming in contact with water saturated rocks. They are known to emit large amounts of steam and gases.


An ash eruption caused possibly by the interaction of viscous magma with water. Alot of steam is emitted.


Sub-glacial eruptions occur when volcanoes hidden under the ice causes the ice to melt eventually giving way for the activity to break out on the surface and into the atmosphere.


The force of submarine volcano eruptions are limited due to the fact that they lay deep under the sea where the pressure is greater. They can either come in the form of an explosive eruption or as pillow lavas at hotspots whereas the magma rapidly cools as it comes into contact with the deep sea water.

Pyroclastic Flow

Pyroclastic flows are one of the most dangerous forms of volcanic eruption made out of hot clouds of gas, ash, and volcanic material which roll down the slopes of a volcano at roaring speeds. They are produced either when a lava dome collapses, or when a dense eruption column collapses under it's own weight. Very common at subduction zone volcanoes.

Nuee Ardente

Similar to a pyroclastic flow these glowing clouds of avalanches are made out of hot gas, ash, and incandescent material. The lighter fraction of gases and ash cauliflowers upwards as the nuee ardente flows down the slopes.


Pretty much like mud. They form when large quantities of water comes together with volcanic debris and can flow down the slopes at high speeds. A prime example of a lahar eruption was at Nevado del Ruiz in Colombia in 1985.

Lava Types

Pahoehoe Lava

Fluid lava which is typically found on hotspot volcanoes with a smooth ropy texture to the surface.

A'a Lava

A more common form of lava flow which cools to a rough jagged surface.

Block Lava

So-called because it comes in the form of blocks of slow moving viscous magma typically produced by subduction volcanoes.

Pillow Lava

Found on the ocean floor, these form a roundish suface which piles on top of each other caused by the rapid cooling of magma when it comes in contact with the seawater.

Eruptive Status


An active volcano erupts on a regular basis every so often. Sometimes you may get volcanoes which are permanently active.


If a volcano has not erupted for 25 years or over then they are classed as dormant volcanoes. They will either erupt again soon or they may be classed as extinct if they've not erupted for centuries.


If a volcano has been inactive for centuries then they may be classed as extinct. It has however been known for an extinct volcano to come back to life after centuries of inactivity.

Location of Volcanoes

Volcanic activity has always been associated with tectonic plate movements on Earth which have been going on for millions of years. Volcanoes are located within 5 different zones in which you will find within or on the edge of each tectonic plate. They are: Hotspots, Continental Margins, Island Arcs, Mid Oceanic ridges, and Continental Rifts.


Hotspot Volcanoes

These are normally located in the middle of a plate and are formed by the upwelling of magma inside the earth known as Mantle Plumes. They usually produce liquid basaltic magma which typically forms a shield volcano. The volcanoes of Hawaii, Galapagos Islands, and Reunion Island are examples of hotspot volcanoes.

Continental Margin Volcanoes

Continental Margin volcanoes are formed as a result of which an oceanic plate is subducted beneath the larger continental plate into the mantle causing partially melted material to rise to the surface, this is called the subduction zone. They typically form Lava Domes and Stratovolcanoes which tend to be the most explosive volcanoes. The volcanoes of the Cascades and Andes mountains are examples of Continental Margin volcanoes.

Island Arc Volcanoes

Another form of subduction zone volcanoes. They work in the same way as Continental Margin volcanoes except an oceanic plate is subducted beneath another oceanic plate forming volcanic islands. Lava Domes and Stratovolcanoes are typically formed. The volcanoes of Indonesia, Japan, and Aleutian Islands are examples of Island Arc volcanoes.

Mid Oceanic Ridge Volcanoes

These volcanic structures form along a long line of fissues running along through the middle of the ocean caused by the upwelling of liquid basaltic magma. Black Smokers are found here and in some cases, volcanic structures form above the surface of the ocean creating islands. The volcanoes of Iceland are a prime example of Mid Oceanic Ridge volcanoes.

Continental Rift Volcanoes

When a landmass splits, it seperates from each other creating a rift valley. Down on the rift valley floor the crust thins out allowing the upwelling of magma to create volcanoes. The volcanoes of East Africa are examples of Continental Rift volcanoes.


Super Volcanoes

Super volcanoes are rare and amongst the hardest to spot but are known to cause catastrophic eruptions which dramatically affects the Earth's climate with an eruption cycle of hundreds of thousands of years. Notable super volcanoes include Lake Toba on the island of Sumatra in Indonesia, Lake Taupo in New Zealand, and perhaps the most famous one of all, Yellowstone National Park which lies in Wyoming, USA. Yellowstone National Park is well known for it's Geysers and it is said that a giant magma chamber lies beneath the national park with an eruption cycle of 600,000 years.

Most Fatalities Caused By Eruption



 Estimated number of deaths caused by eruption


 Tambora, Indonesia



 Krakatau, Indonesia



 Pelee, Martinique



 Nevado del Ruiz, Colombia



 Unzen, Japan



 Laki, Iceland



 Kelut, Indonesia



 Santa Maria, Guatemala



 Kelut, Indonesia



 Santiaguito, Guatemala



 Galunggung, Indonesia



 Vesuvius, Italy



 Vesuvius, Italy



 Awu, Indonesia



 Merapi, Indonesia



 Papandayan, Indonesia



 Lamington, Papua New Guinea



 Awu, Indonesia



 El Chichon, Mexico



 Nyiragongo, DR Congo


Volcano Simulator

To get a visual idea of how a volcano behaves you might want to check out the volcano simulator page featured on the Alaska Museum of Natural History website.