Geology notes november 10 for exam 3

Geology notes - Elastic rebound theory Seismic waves are the energy released as rocks snap back to their preferred shape after a break occurs

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Geology The San Andreas is a right lateral strike-slip (horizontal motion) fault -It forms the tectonic boundary between the Pacific Plate and the North American Plate. Most earthquakes occur at plate boundaries Plate motion causes deformation at plate boundaries causing a buildup of stress that is released by earthquakes. The deformation can be elastic and plastic -Elastic deformation- object returns to its original shape when stress is removed (ex. Rubber band) -Plastic deformation- object does not return to its original shape when stress is removed (ex. Gum) Stress causes strain and then failure Plastic deformation produces folds Rock failure produces faults Normal faults are caused by tension which pulls the rocks apart -The hanging wall drops down Reverse (or thrust) faults are caused by compression as rocks are pushed together -The hanging wall rides up over the footwall Strike- slip faults are caused by shear as rocks slide past each other in a horizontal plane -The hanging and footwalls stay at the same elevation
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Unformatted text preview: Elastic rebound theory: Seismic waves are the energy released as rocks snap back to their preferred shape after a break occurs Seismic waves carry energy away from the break-Primary waves have push-pull motion and move the highest velocity-Secondary waves have side-to-side motion and move slower than primary waves-Surface waves can have side to side (Love waves) or up and down (Rayleigh waves) motion The epicenter is the point on the ground surface directly above the focus The focus is the location on the fault where the break occurred Seismographs register the arrival time of seismic waves-Inertia holds mass at a fixed position while the recorder moves relative to it-Records horizontal and vertical motion Primary waves travel faster than Secondary waves so they arrive at the seismograph first The earthquakes location can be determined by plotting distances from three different seismographs The distance and magnitude of an earthquake can be determined from the seismogram...
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This note was uploaded on 08/09/2011 for the course GEOS 1004 taught by Professor Aksinha during the Fall '08 term at Virginia Tech.

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Geology notes - Elastic rebound theory Seismic waves are the energy released as rocks snap back to their preferred shape after a break occurs

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