Earth Sciences 1022A/B Lecture 10: Earth Sciences 1022A – Lecture 10 – Earthquakes
7 Dec 2015
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Earth sciences 1022a lecture 10 earthquakes. Mainly by elastic-rebound of the crust as stress builds up. Rocks bend, then eventually rupture at the hypocenter and energy radiates in all directions. Then the cycle starts over as rocks start bending again. Foreshocks and aftershocks accompany the main event with some earthquakes. Uses tremor-detaching seismographs to record vibrations as surface waves, and body waves that travel through rock. Surface waves: slowest, long waves travel on the surface like ripples on water. Compressional: push, pull, faster primary p waves travel in the direction of initiation. Shear: slower secondary s waves travel perpendicular to the direction of initiation. Record s and p waves" arrival times to find the epi center. Plot of maps from 3 stations, where circles intersect is where epi center is. Measure by richter scale: measure magnitude based on amplitude, each number is 10x largest waves amplitude or 32x the energy.
