Details Title: Earthquakes and Volcanoes Final Description: FML Total Flash Cards: 42 Created: 05/03/2009 16:29:36		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Geology Flashcards
Cards in this set: Term Stratovolcanic Definition explosive eruptions of new volcanic material-extremely hazardous. average lifetime: 900,00-1,000,000 years Flank and Summit eruptions are common form at subduction zones concave upward occur on landward side of subduction zones they are stratified Term Shield Volcanoes Definition More voluminous then strato concave downward Term Cinder Cones Definition Moderately explosive eruptions of new volcanic material average lifetime= 1-100 years frequently form on flanks & summits of larger stratovolcanoes steep conical hills of volcanic fragments that accumulate around and downward of the vent Term Pyroclastic Material Definition Tephra, ejected material of all sizes solid by the time it hits the ground most numerous type volcano rarely reactivated Term Spatter Cones Definition similar to cinder cones except that some of the material is still molten when it reaches the ground relative to cinder cones, are smaller and have a shorter lifetime Term Lava Domes Definition Effusive eruption of new volcanic materials average lifetime:1-100 years Usually form after the explosive eruption of gas-rich magma at stratovolcanoes Rounded steep sided mounds of lava formed near the volcanic vent by very viscous magma one or more individual lava flow Term Caldera Definition Large, circular, steep walled depression at the summit of a volcano up to 10 km in diameter walls up to 100 m high Term Crates Definition smaller, circular depressions formed by the explosive evacuation of rock during eruptions Term Explosive disintegration of the top of a volcano collapse of the top of a volcano into empty underground magma chamber Definition Caldera formed by... Term Complex Volcanoes Definition Volcanoes of mixed origin, stratovolcano with lava domes overlapping stratovolcanoes with multiple summits Due to changes in eruption habit, location of principle vent area Term Maar Definition A wide, low, relief crater formed by shallow explosive eruptions Generally no new volcanic material erupted Groundwater is heated and boils causing steam explosions Often filled with water to form lakes Term Tuff Rings Definition Explosive eruptions of new volcanic material and excavated country rock Triggered by interaction of water and rising magma Built of multiple pyroclastic surges that build ring of debris around explosion crater Term Caldera Definition a large depression created by the collapse of a volcano Term Cinder Cone Definition A simple volcano built from blobs of lava ejected from a single vent Term Shield Volcano Definition Built from countless outpourings of fluid lava flows Term StratoVolcano Definition built of layers of lava, ash, and volcanic debris Term Lava Dome Definition mound formed when viscous lava pulls up around vent Term can be located anywhere at tectonic plate boundaries or in the center plates in continental or oceanic crust Definition Hot Spot Locations Term Hot Spots Definition Mantle plumes rise from deep within the mantle, possibly the core-mantle boundary rise via convection when reaches base of lithosphere, plume head spreads out, potentially feeding multiple volcanoes simultaneously Term plumes are stationary for millions of years, provide a continuous source of magma. As the tectonic plate moves over stationary mantle plumes, a line of volcanoes is formed, only volcanoes immediately over plumes are active Definition Formation of Hot Spot tracks Term typically produce shield volcanoes the largest volcanoes are immediately above the hot spot once the supply of lava is turned off the island moves away from the hot spot, the volcano gets smaller Definition Hot spot occurrences under oceanic crust Term Atoll Definition a coral island that encloses a lagoon and is surrounded by open sea Term Seamount Definition Volcano and reefs sink below sea level Term Galapagos Definition Since formation completely isolated from mainland plants and animals only reached island by chance allowed many unique plants and animals to form composed primarily of large shield volcanoes Term Azores Definition Islands composed primarily of stratovolcanoes Term Iceland Definition Combination of hot spots and divergent plate boundary as tectonic plates move about surface of earth, oceanic spreading center coincidentally moves over a hot spot double dose of volcanism created the topographic high Term Best place to harness geothermal energy Geothermal plants provide reliable power for 60 million people in the world Iceland is almost run entirely on geothermal energy Definition Plate Boundaries Term Shake River Plain Definition thought to be a continental hot spot track flat area lacking topography, resurfaced by erupted lava oldest part of plain in vicinity of columbia river flood basalts Term Afar, Africa Definition Combination of a hot spot and divergent plate boundary, progression from hot spot to oceanic spreading center hot spots may play a critical role in military continental break up. Term high efficiency and low cost lower co2 emissions than fossil fuels Definition Advantages of geothermal energy Term scarcity of suitable sites depleted if used to rapidly moderate to high local air pollution noise and odor cost too high except at the most concentrated and accessible source Definition Disadvantages of geothermal energy Term Rift Valleys Definition covered with loose sediment and lava flows deep cracks run parallel to the rift valley normal faults parallel rift valley and create steep valley walls Term Effusive submarine eruptions 20 eruptions/ year worldwide none have been directly witnessed Definition how the mid ocean ridge system works Term Magma Chambers Definition Creservoirs of molten lava, exists 1-3 km below ridge axis height and width: a few km's segmented only the uppermost portion of chamber fully melted Term Magma rises from magma chambers to shallow depth Rising Magma temporarily fills in cracks between spreading plates additional lava erupts onto ocean floor to form pillow basalts Definition Types of Eruptions Term Pillow Basalts Definition Lava squeezes out like toothpaste through the thin skin of the flow The surface of the exposed lava quickly solidifies, forming a pillow like structure Term Hydrothermal circulation of ocean water Definition seawater drawn into oceanic crust along the sides of rift As water approaches underlying magma chamber, it is heated heated water dissolves various metals and other elements hot water rises and is ejected at submarine hot springs Term Unique Ecosystems Definition Dissolved metals come out of solution making water look black Bacteria derive energy from chemosynthesis(energy from chemical reactions) as opposed photosynthesis supports incredible and diverse ecosystem with well developed food web Term Volcanic Hazards Definition Effusive Eruption: Lava Flows Explosive Eruptions: Pyroclastic flows, lahars, ash fall, ash clouds, phreatic eruptions All eruptions/volcanoes: volcanic gas, landslides, tsunami Term lahars Definition rapidly flowing mixture of rock debris and water can travel 10's of km typically down river valleys hot or cold especially common at stratovolcanoes Term without eruption: landslides mixed with water During eruptions: melting of snow and ice by pyroclastic flows, lava flows After eruptions:heavy rainfall, erodes deposited ash, sudden release of water from crater lakes Definition How lahars are generated? Term destroy by direct impact, often contain larger boulders and trunks bury buildings, communities and valuable land in cement like layers of rock debris May trap people block tributary streams creating lakes that may suddenly flood Definition Effects of Lahars