Hot spot volcano
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A hot spot volcano is produced by a thermal plume at the mantle-crust boundary. The hot spot acts like a blow torch as it melts the overlying mantle and forms plumes of lava which rise up to the surface. Hot spot volcanoes can be recognized by a trail of extinct or dormant volcanoes that were at one time above the hot spot, but became extinct as the tectonic plate they are situated moved away from the active hotspot.
An example of this type of hot spot activity is the Hawaiian Islands. The big island of Hawaii is currently on the hot spot. Older islands have since moved away as the Pacific Plate moves in a northwest direction. Therefore, the islands of Maui, Lanai, Molokai, Oahu and Kauai are consecutively older as each used to be over the hot spot at one time and have since moved away.
Other hotspot volcanoes include the supervolcano at Yellowstone, the Galápagos Islands and Iceland.
[edit] Hot Spots versus Island Arcs
Hot spot volcanoes should not be confused with island arc volcanoes. While each will appear as a string of volcanic islands. Island arcs are formed by subducting, converging tectonic plates. When one oceanic plate meets another, the denser plate. forced downward into a deep ocean trench. This plate melts and becomes new molten material that fuels a chain of volcanoes, such as the Aleutian Islands near Alaska. A volcanic hotspot is a large magma chamber which builds pressure as the magma accumalates and is unable to find escape through the Earths crust. When the pressure is great enough, explosive eruption occurs.
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