Volcanoes

__Magma__ is the hot, melted, molten rock located below the Earth's surface. When the magma reaches the surface it is called __lava__. Lava is leaking magma, therefore leaking mantle.


 * __3 Different Kinds Of Volcanoes__**
 * Subduction Zones
 * Where two tectonic plates are colliding with each other, and one is forced under another.
 * The edge of plates can sometimes be known as a "Ring of Fire". The subduction zones around the Pacific Basin have caused hundereds of volcanoes around Asia and America.
 * Spreading Zones (divergent plate boundaries)
 * New plate material forms when two plates diverge from each other
 * Iceland is a volcano formed from the Mid-Atlantic Ridge.
 * Hot Spots
 * Leaks in spots around the crust cause volcanoes in areas other than plate boundaries.
 * The Hawaiian islands formed from a hot spot system. As the Pacific plate moves, the location of the Hawaiian islands also shifts and a new island can be formed. Currently, a new island is forming underwater and will eventually create an additional island to the Hawaiian archipelago.

__**3 Different Classifications of Volcanoes**__
 * Extinct- no volcanic activity, no potential to erupt
 * Dormant- occasional small volcanic activity, and the earthquake has the potential to still erupt
 * Active- currently displaying volcanic activity, potential to have small or large eruptions at any time

__**Environmental and Economic Effects of Volcanoes**__
 * Volcanic explosion can cause displacement and movement of bedrock, affecting structures
 * Molten and hot lava melts and kills everything its path
 * New rock is formed on top of pre-existing environments- requires primary succession to reestablish life
 * Damage to infrastructure can be costly
 * Ash cloud from explosion can cause lung irritation
 * Ash cloud from explosion can disrupt animal migration and habitat
 * Ash cloud from explosion can block out sunlight, creating a "nuclear winter" and blocking out the sun for long periods of time, reducing temperatures and making photosynthesis impossible
 * HOWEVER- volcanic areas can be sites of useful geothermal heat if the volcano is not intensely active

__**Historic Volcanic Eruptions**__ //Mount Pinatubo//- largest volcanic eruption in the 20th century (1991)
 * Located in the Philippines
 * 200,000 were evacuated but still 338 people died
 * resulted in a slight cooling of global temperatures for about one year