Geophysics - Geophysics Test 1 Geophysics the study of...

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Geophysics Test 1 Geophysics- the study of earths (and its atmosphere) by the quantitative observations of their physical properties By measuring the strength and orientation of the magnetic field on the round surface, one could obtain information about buried rocks Plate tectonics: Divergent plate boundary- two neighboring plate move apart (spreading center) Contain shallow small earthquakes 1-10km deep Convergent Plate boundary- (subduction zone) one plate slides under the other plate Contain shallow to deep earthquakes 100-700km deep Transform Plate Boundary- two neighboring plates move past each other in opposite direction Contain small to medium earthquakes 1-100km deep Mantle: The mantle consists of all the layers above the liquid outer core except the crust. The mantel is made up of the Lithosphere, Asthenosphere, and the Mesosphere. The Lithosphere and the Mesosphere are both hard solid or crystalline while the Asthenosphere is more like a liquid consisting of very little crystals. The Lithosphere, which also consists of the crust, is about 100-150km thick. The crust makes up between 10-35km of the 100-150km. Continental crust is thicker and more buoyant than oceanic crust. The Lithospher is broken up into plates. These plates are allowed to move around over the asthenosphere due to its soft ductility and thermal convection currents. The Asthenosphere is around 550-600km thick (700km from earths surface)
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Thermal convection- heated water loses density causing it to rise, as it reaches the surface, the water cools and falls back down This same phenomenon happens in the asthenosphere, which causes the lithosphereic plates to move. Convection currents cause either ridge push or divergent plated boundaries or convergent plate boundaries. Divergent zones can be created underneath a continent creating continental rift valleys. In these areas the asthenosphere bulges underneath the lithosphere creating faulting. These faults create horst and grabens which are high and low points along the normal faults. These areas have tensional stress. Once the rift valley spreads far enough apart, many times ocean water rushes in and creates a sea much like the Red Sea. A rift zone is also located in the western United States. This rift zone created the Basin and Range Province. The Basin and Range province is what created the Rocky Mountains. Soon the spreading allows magma to reach the surface and begins to create oceanic crust and a new ocean basin. A prehistoric example of this would be the breaking apart of pangea. Decompression Melting- as the Asthenosphere rises at spreading zones, decompression occurs
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Geophysics - Geophysics Test 1 Geophysics the study of...

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