Three Types of Magma

Basalt

• One of the most common types of magma is "basalt" magma, which occurs in thin flows. This slow moving magma also maintains the highest temperature at close to 1,200 degrees Celcius. Another characteristic of basalt magma is the low silica and gas content, as well as the low viscosity. The low gas content leads basalt magma to be relatively tame and unexplosive compared to the other types. Most of the oceanic crust forms from basalt magma.

Andesite

• "Andesite" magma makes up the middle-ground of the magma types. It has a lower temperature than basalt, only reaching 1,000 degrees Celsius. The gas and silica content are moderate -- meaning that andesite magma is only moderately explosive. It also flows much more thickly than basalt and also exhibits itself in ash debris from eruptions.

Rhyolite

• The third -- and perhaps most intimidating -- type of magma is "rhyolite" magma. It emerges at a lower temperature, hovering right around 800 degrees Celcius. This magma is rich in silica, contains a high viscosity, as well as an extremely high gas content, making this type of magma very explosive. For the most part, rhyolitic magma emerges as ash. However, as the gas content lowers, the lava will begin to flow more like basalt magma.

Types of Eruptions

• The type of lava present will depend upon the type of eruption. "Hawaiian" eruptions contain basaltic magma, which is one reason why the eruptions are so tame. "Vulcanian" eruptions often create pyroclastic flows, where andesite magma spews from the vent and then collapses back to earth. "Plinian" eruptions spew rhyolitic magma, which can flow miles into the air. The ash-debris from these types of explosions can travel around the globe.