* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Document
Axial Seamount wikipedia , lookup
Mono–Inyo Craters wikipedia , lookup
Mount Pinatubo wikipedia , lookup
Mount Garibaldi wikipedia , lookup
Itcha Range wikipedia , lookup
Mount Meager massif wikipedia , lookup
Llullaillaco wikipedia , lookup
Mount St. Helens wikipedia , lookup
Craters of the Moon National Monument and Preserve wikipedia , lookup
Level Mountain wikipedia , lookup
Large igneous province wikipedia , lookup
Mount Pleasant Caldera wikipedia , lookup
Cerro Blanco (volcano) wikipedia , lookup
Lascar (volcano) wikipedia , lookup
Olympus Mons wikipedia , lookup
Potrillo volcanic field wikipedia , lookup
Nevado del Ruiz wikipedia , lookup
Mount Vesuvius wikipedia , lookup
Mount Pelée wikipedia , lookup
Volcanology of Io wikipedia , lookup
Mount Edziza volcanic complex wikipedia , lookup
Cascade Volcanoes wikipedia , lookup
Wells Gray-Clearwater volcanic field wikipedia , lookup
Volcano (1997 film) wikipedia , lookup
Cerro Azul (Chile volcano) wikipedia , lookup
Volcanism • • • • • Volcanic Features Location and Types of Volcanic Activity Effusive Eruptions Explosive Eruptions Volcano Forecasting and Planning Volcanoes VOCABULARY volcano hot spot How and Where Volcanoes Form Volcanic activity takes place primarily at subduction boundaries, 1. Water in the subducted rock is released into the asthenosphere. 4. Some of the magma reaches Earth’s surface, and volcanoes form on the overriding continental plate. Oceanic lithosphere Asthenosphere 2. The water lowers the melting temperatures of materials in the asthenosphere, leading to magma formation. Continental lithosphere 3. The magma is less dense than its surroundings, so it rises. Volcanoes VOCABULARY How and Where Volcanoes Form volcano hot spot Magma and volcanoes also form at hot spots. Kauai Direction of Plate Movement Oahu Molokai Lanai Maui Hawaii The Hawaiian Islands formed over a hot spot. How Magma Rises Volcanic Settings Plate Tectonics and Magma Generation Major Volcanoes Around the World Magma and Erupted Materials Gases escape easily from basaltic magma, generating relatively quiet eruptions. Hardened basaltic lava flows on land are characterized as pahoehoe or aa; if the lava cools underwater, it is characterized as pillow lava. A.Parameters of volcanism: 1.Viscosity 2.Chemistry of Magma 3.Gases within the magma 4.Water content of magma Magma and Erupted Materials Magma and Erupted Materials VOCABULARY viscosity lava pahoehoe aa pillow lava pyroclastic material pyroclastic flow Viscosity: Viscosity is a measure of how thick (viscous) and sticky a liquid is. Lava Flows • Lava Flow - A 'stream' of molten rock • 'aa' lava flow - jagged, rubbly, broken surface • 'pahoehoe' lava flow smooth, ropy surface Magma andand Erupted Magma EruptedMaterials Materials Basaltic Magma AndesiticMagma Rhyolitic Magma Silica Content Least (~50%) Intermediate (~60%) Most (~70%) Gas Content Least Intermediate Most Viscosity Least viscous Intermediate Most viscous Type of Eruption Rarely explosive Sometimes explosive Usually explosive Melting Temp. Highest Intermediate Lowest Rifts, oceanic hot spots Subduction boundaries Continental hot spots Location Volcanic Landforms A volcano’s shape and structure depend on how it erupts and what materials are released. Shield volcanoes are formed by basaltic lava that flows long distances before hardening. Tectonic Settings and Volcanic Activity Intrusions classified by Igneous __________shape, size, and orientation There are three types of volcanic cones: Cinder – explosive eruptions, small but • ______ steep slopes, pyroclastics. Shield – non-explosive eruptions, fluid • _______ basaltic lava, gentle broad slopes. Composite – alternating between lava and • _________ pyroclastics, explosive and non-explosive eruptions, steep and tall. Volcano Types Volcanoes Volcanic Landforms VOCABULARY shield volcano cinder cone composite volcano lahar caldera lava plateau A volcano’s shape and structure depend on how it erupts and what materials are released. Shield volcanoes are formed by basaltic lava that flows long distances before hardening. Shield Volcano Shield and Composite Volcanoes Volcanoes Volcanic Landforms Cinder cones are formed when molten lava is thrown into the air from a vent and breaks into drops. These drops harden into cinders that form a steep cone around the vent. Cinder Cone Volcanoes Volcanic Landforms Composite volcanoes are formed by layers of pyroclastic materials and lava that have erupted in the past. Composite Volcano Composite volcanoes Debris Avalanche and Eruption of Mount St. Helens, Washington Nuee ardente: pyroclastic flow, of searing superheated gas and incandescent volcanic ash and dust Mount Pelee, on the Carribean island of Martinique, 1902 eruption. All but 2 of the more than 20,000 people in the town of St. Pierre were killed. Volcanoes Volcanic Landforms A caldera is a large crater-shaped basin that forms when the top of a volcano collapses. Formation of Crater Lake EFFUSIVE ERUPTIONS • Generally at hots spots, spreading centers • Mantly comes directly to surface • Hot lava; low viscosity, very mafic, flows easily, gases escape easily • Forms shields, flood basalts EXPLOSIVE ERUPTIONS • Found at subduction zones • Magma low temp (800 degrees C), high viscosity, does not flow easilty, more felsic mineralogy, gases trapped, hard to predict explosions • Forms composite volcanoes, cinder cones, calderas, aerial bombs, nuee ardente gas flows, very destructive