Earth Sciences 1022A/B Lecture Notes - Lecture 9: Seismic Wave, Epicenter, Richter Magnitude Scale

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 1022A/B
• Professor: Stephen R Hicock

Document Summary

Slippage along a fault in the crust at the hypocenter. Occurs below the spot plotted on a map called the epicenter. Elastic rebound: rocks bend until eventually the rupture at the hypocenter and energy radiates in all directions then the cycle starts over as rocks start bending again; mainly happens at plate boundaries. Foreshocks and aftershocks accompany the main event with some earthquakes. Compressional (like slinky toy) primary (p), faster. Shear (starts with up and down motion) secondary (s), slower. Record p, s wave arrival times, time different on time-travel curves gives the distance from the station to the epicenter. Plot distance from at least 3 stations as arcs, 3 arcs intersect at the epicenter. Richter scale: based on energy released by the earthquake. Each number 10 times largest wave amplitude or 32 times the energy of the last number. At material boundaries part of a seismic wave is reflected, part refracted.