Earth Sciences 1022A/B Lecture Notes - Lecture 10: Wind Wave, Seismic Refraction, Outer Core
19 Oct 2016
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Document Summary
Slippage along a fault in the crust at the hypocentre. Occurs below the spot plotted on a map called the epicentre. Rocks bend until they rupture (earthquake), then stress builds up and they start bending again (diagram in notes) Foreshocks and aftershocks common with the main event. Body waves: travel through rock: compressional (like slinky toy), primary (p) faster, shear (starts with up and down motion), secondary (s), slower. Record p, s wave arrival times, time difference on time-travel curves gives the distance from the station to the epicentre (diagram in notes) Plot distances from at least 3 stations as arcs; 3 arcs intersect at the epicentre. Richter scale: based on energy released by the earthquake (diagram in notes: each number 10 times largest wave amplitude or ~32 times the energy of the last number, moment magnitude better for large earthquakes. At material boundaries part of a seismic wave is re ected, part refracted.
