EAS205 Lecture : Topic 2 - Earthquakes.pdf
8 May 2014
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Document Summary
Sudden slippage (rupture) along fault zones in response to stress: seismic slip. Can form new faults or rejuvenate old faults. Defined as applied force: horizontal or vertical. Forces pulling in opposite directions: tensile, shearing. Deformation is the visual expression: can be permanent (plastic, or temporary (elastic, rupture. Low t and p: near surface environments, elastic, ruptures are common. High t and p: usually at great depths (often >100 km, may involve long term stress, plastic, may rupture. Faults and earthquakes are related, but . Main mechanism reid"s elastic rebound theory: case study san francisco 1906 earthquake, measured strain build up in the region, after the quake > fault rupture and displacement. Earthquake: elastic deformation prior to failure, sudden displacement along fault (seismic slip, elastic rebound as rocks snap back to previous dimensions. Hypocentre: earthquake focus, point on the fault of first movement, point on the surface directly above the hypocentre. Two main wave groups: body (p, s)
