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Volcanoes and Plate Tectonics (69) What Are Volcanoes? • A volcano is an opening in Earth that erupts gases, ash, and lava. • Volcanic mountains form from layer of ash and lava. • Earth has approx 600 active volcanoes Most Active Volcanoes • Kilauea located in Hawaii, is the world’s most active volcano • Eruptions from Kilauea began in January 1983 and still continues. Kilauea • http://www.telegraph.co.uk/news/worldnew s/australiaandthepacific/hawaii/8365606/H awaiis-Kilauea-volcano-erupts.html Iceland • Land of fire and ice. • Sits on a divergent plate boundary. • Lava flows destroy everything in their path • Falling volcanic ash can collapse buildings, block roads. • http://www.bbc.co.uk/new s/world-europe-15995845 Magma Forced Upwards • Deep inside Earth, heat and pressure changes cause rock to melt, forming liquid rock or magma. • Magma is less dense than the rock around it, so it is forced slowly toward Earth’s surface. • Magma reaches Earth’s surface and flows out through an opening called a vent. • Lava, cools quickly solidifies, forming igneous rock layers around the vent. • The steep walled depression around a volcano’s vent is the crater • Volcanoes form in places where plates are moving apart, moving together, and at locations called hot spots. • Example of a hot spot is the formation of the Hawaiian Islands. Hot Spots • Hawaiian Islands created because of volcanic activity. • Hot rock forced toward the crust where it melts partially to form a hot spot. • Pacific Plate is moving over a stationary hot spot. • http://www.history.com/sho ws/how-the-earth-wasmade/videos/how-washawaii-formed#how-washawaii-formed • The opening in a volcano from which lava flows is called the __________. • A. plate • B. shield • C. tephra • D. vent The steep-walled depression around a volcano’s vent is a __________. • A. crater • B. rift • C. shield • D. trough • What is a hot spot? Hot rock that is forced toward the crust partially melts, forming what are known as hot spots. The Hawaiian Islands sit on top of a hot spot under the Pacific Plate.
