EOSC 114 Lecture Notes - Lecture 6: Convergent Boundary, Asthenosphere, Plate Tectonics
12 Sep 2016
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Dramatic destruction of buildings, injuries, fatalities, tsunamis. Disturbing what appears static and solid is moving violently. Earthquake vibrations or waves produced by plate motions. Earthquakes are usually associated w/ the rupture of a fault. Accumulated stress is released as seismic wave energy. Seismic waves radiate through earth"s interior and surface, causing shaking. Divergent boundaries are more shallow so earthquakes are less frequent/weaker. Subduction/convergent pulls plate under earth as deep as 700kkm. Why earthquakes occur: rupture of a fault, movement of magma, landslides, other rapid release of energy that shakes the ground. Convergent plate margin caused by compression: tension. Divergent plate margin caused by tension: shear stress (transverse) When a solid material is put under stress, it will respond by deforming (undergoing strain). Change in shape or size due to stress: elastic deformation. Recovers when stress is removed: plastic (ductile) deformation. Controlled by: temperature and pressure, the speed of deformation, duration of deformation. A large brittle fracture in a rock body.
