GEOL 101 Lecture Notes - Lecture 13: Seismic Wave, Epicenter, Linear Elasticity
11 Jan 2017
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Document Summary
Earthquake: motion of the ground that occurs when brittle rock under stress suddenly beaks along a fault. Faults come at all length scales, from mm to separation of lithospheric plates. Device used to record motions of the earth: mass is coupled to earth by a spring, motion of mass is damped compared to earth motion, relative motion is traced by pen on the chart. Study of the propagation of mechanical energy that released by earthquakes and controlled explosions. Waves begin because of initial tension of compression in the rock. Difference between arrival times of p and s waves is a function of the distance to the epicenter. At least three stations needed to determine location of epicenter. Travel time curve: difference between p and s arrival times difference in creases with distance to epicenter. Geologists determine location by matching seismograms to travel time. Geologist draws circles on the globe with radius calculated from travel time curves.
