What type of volcanoes are there

Lava domes are built up when the lava is too viscous to flow , according to the U. A bubble or plug of cooling rock forms over a fissure. This cooler, thick lava usually rises near the end of an explosive eruption and lava domes often form within the craters of stratovolcanoes. Helens has several well-defined lava domes inside the crater , according to NASA. Besides well-known symmetrical volcanoes such as Mount Fuji in Japan and Kilimanjaro in Tanzania, volcanic activity is responsible for several other distinctive landforms.

Calderas : A caldera is a bowl-shaped depression formed when a volcano collapses into the void left when its magma chamber is emptied. There are three types , according to San Diego State University. The first type is a crater lake caldera. This is the result of a stratovolcano collapsing into its magma chamber during a violent eruption. Basaltic calderas have a concentric ring pattern resulting from a series of gradual collapses rather than a single event. They are often found at the summit of shield volcanoes such as the craters at the tops of Mauna Loa and Kilauea.

Resurgent calderas are the largest volcanic structures on Earth. They are the result of catastrophic eruptions that dwarf any eruptions ever recorded by human beings.

Yellowstone caldera, sometimes called a "super volcano," is one example. Volcanic plugs : When magma solidifies in the fissure of a volcano the hard dense rock may form a " neck " that remains when softer surrounding rock has been eroded away, according to the U. Tuff cones : also known as maars, tuff cones are shallow, flat-floored craters that scientists think formed as a result of a violent expansion of magmatic gas or steam, according to the U. Maars range in size from to 6, feet 60 to 1, meters across and from 30 to feet 9 to meters deep, and most are commonly filled with water to form natural lakes.

Maars occur geologically young volcanic regions of the world such as the western United States and the Eifel region of Germany. Lava plateaus : Shield volcanoes may erupt along lines of fissures rather than a central vent spilling liquid lava in successive layers. Over time as these layers form broad plateaus such as the Columbia Plateau, according to the Encyclopedia Britannica. Stratovolcanoes are more likely to produce explosive eruptions due to gas building up in the viscous magma.

Andesite named after the Andes Mountains , is perhaps the most common rock type of stratovolcanoes, but stratovolcanoes also erupt a wide range of different rocks in different tectonic settings.

Stratovolcanoes, also known as composite cone volcanoes, erupt viscous lava that forms a steep-sided, triangular-shaped structure. Its last known eruption was in The low afternoon sun emphasises the conical shape of the volcano. As viscous lava is not very fluid, it cannot flow away from the vent easily when it is extruded.

Instead it piles up on top of the vent forming a large, dome-shaped mass of material. Magma is stored beneath a volcano in a magma chamber. When a very large, explosive eruption occurs that empties the magma chamber, the roof of the magma chamber can collapse to form a depression or bowl with very steep walls on the surface.

These are calderas and can be tens of miles across. Calderas can also be formed during an eruption that removes the summit of a single stratovolcano. Caldera-forming eruptions can remove massive portions of a single stratovolcano. The top can literally be blown off! Unlike shield volcanoes, composite volcanoes have a distinctly conical shape, with sides that steepen toward the summit.

Cinder cones are the smallest, and almost too small to see next to a volcano like Mauna Loa. Eve Cone is a cinder cone on the flanks of Mt. Edziza in northwestern British Columbia. It rises m above the landscape, and has a diameter of under m. Cinder cones have straight sides, unlike upward-steepening composite volcanoes, or rounded shield volcanoes. The low viscosity of the lava means that it can flow for long distances, resulting in the greater size of shield volcanoes compared to composite volcanoes or cinder cones.

Composite volcanoes, like Cotopaxi in Figure The layers strata is where the alternative name, stratovolcano comes from. Cotopaxi displays the characteristic shape of composite volcanoes, which have slopes that get steeper near the top of the volcano.

Composite volcanoes typically erupt higher viscosity andesitic and rhyolitic lavas, which do not travel as far from the vent as basaltic lavas do. This results in volcanoes of smaller diameter than shield volcanoes.

What are the three main volcanoes? There are three main types of volcano - composite or strato, shield and dome. Composite Volcanoes Composite volcanoes, sometimes known as strato volcanoes, are steep sided cones formed from layers of ash and [lava] flows.

The eruptions from these volcanoes may be a pyroclastic flow rather than a flow of lava. A pyroclastic flow is a superheated mixture of hot steam, ash, rock and dust. A pyroclastic flow can travel down the side of a volcano at very high speeds with temperatures over degrees celsius.

Composite volcanoes can rise over feet. A simple cross section through a composite volcano When composite volcanoes erupt they are explosive and pose a threat to nearby life and property. Eruptions are explosive due to the thick, highly viscous lava that is produced by composite cone volcanoes. This viscous lava has a lot to do with why they are shaped the way they are.