Volcanoes

A volcano is one of the most powerful forces in nature. However we never really think about how they work. At most people in general probably only remember that there are holes in the Earth’s crust that allow magma to seep out. This is only part of the story of how volcanoes are born.

To understand how volcanoes are formed we need to know about plate tectonics. One of the reasons why there are ruptures in the Earth’s crust is that the crust is not one whole piece. It is actually a set of interlocking plates that are either pulling away from each other or colliding. This process is creates boundaries of volcanic and seismic activity called plate boundaries. So if you were to go to a particular plate boundary you would be sure to see some volcanic activity.

The most common form of volcanic activity is actually underwater. The stress of the tectonic plates pulling a way from each other along what is called a divergent plate boundary creates weak spots in the thinner oceanic crust. This allows the mantle below to melt through creating new sea floor in a process called sea floor spreading. However this is not the only kind of activity that occurs.

The mantle can create weak spots in the Earth’s Crust independent of the plate boundaries. In this case the convection currents create something called mantle plumes. These are concentrated updrafts of heated magma. This concentration of magma creates weakened areas in the crust called hot spots. These hotspots are responsible for the formation of Island chains like the the Hawaiian islands.

Convergent boundaries can also create volcanoes. The process is similar to hot spots. When oceanic crust of one plate subducts beneath the continental crust of another, it melts into magma. The upper continental crust has brakes in the from of faults and other fissures and in some cases these are deep enough to allow magma to flow to the surface.

Read more: http://www.universetoday.com/60019/how-volcanoes-work/#ixzz2E4uBwhci