ENVIRSC 1G03 Lecture Notes - Lecture 11: Iris Consortium, Richter Magnitude Scale, Seismogram
7 Dec 2016
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Document Summary
S waves do not penetrate beyond 2900km depth. How do we detect and record seismic waves: using a seismograph a tool that records seismic waves. Must be attached to the ground: produces a seismogram: a record of seismic waves. Remember that seismic waves travel at different speeds. Recall that p waves arrive before s waves: the difference in arrival time increases with distance from epicenter. It is the distance estimated by between different wave arrivals. P waves outrun the s waves through the interior; the farther the distance to the seismograph, the greater the discrepancy. The closer you are to the epicenter, the more overlapping waves there are (most motion) generated at the same time. The global seismographic network consists of seismograph stations which transmit their data live over the internet. The earthquake magnitude is proportional to the max. amplitudes on seismograms. The richter magnitude scale compensates for decreasing amplitude with increasing distance from epicenter.
