What Makes a Volcano Explosive?

A volcano is an opening where magma erupts onto the surface as lava after rising from deep within the Earth. Not all magma is the same. Some magma contains as much as 75% silica (SiO2), whereas other magma contains as little as about 50%. The more silica in a magma, the higher its viscosity, or resistance to flow. Viscosity controls the type of volcano that forms. Eruptions of high-viscosity magma build very steep-sided lava domes. Low-viscosity magma produces cinder cones and thin sheet-like lava flows, and intermediate-viscosity magma creates moderately steep mountains called stratovolcanoes.
(Source: USGS)

Learn more about volcanoes in Alaska at the Alaska Volcano Observatory website.

 

Volcano Simulator © 2006 by CG Science.

Bookmark and Share

Planet Store
Ursus spelaeus, Cave Bear Skull & Lower Jaws
Ursus spelaeus, Cave Bear Skull & Lower Jaws   
Kids Trex Dinosaur Face Mask For Fun & Protection
Kids Trex Dinosaur Face Mask For Fun & Protection   
Mesohippus bairdi, authentic horse skull
Mesohippus bairdi, authentic horse skull   
Roadside Geology of West Virginia book
Roadside Geology of West Virginia book   
Planet Store

Geologic History of West Virginia
Free Book Download:
Geologic History of West Virginia by Dudley H. Cardwell (1977)
>> Download the Book