GEOL 213 Lecture Notes - Lecture 11: Mercalli Intensity Scale, Seismometer, Seismogram

• School: College of Charleston
• Department: Geology and Environmental Geosciences
• Course: GEOL 213
• Professor: Jaume'

Document Summary

Size of earthquakes is related to the size of fault surface rupture. Maximum possible earthquakes can be estimated from the longest mapped fault. Relatively few large earthquakes have occurred along the himalayan front historically, but in. Larger earthquakes rupture longer pieces of fault general longer ruptures = larger magnitudes. Modern units for earthquake size are seismic moment (m 0 ). Related to the amount of energy released in an earthquake. A = area of fault that moved u = average slip on fault. To be consistent with historical practice, moment magnitude (m w ) is defined: Charles richter devised the original magnitude scale in 1935. Related amplitude of recorded seismic waves to the size of earthquake. Currently many variations on richter"s original formulation. Ritcher"s nomogram uses distance (or s-p time) and amplitude on seismogram (wood-anderson seismometer) to measure magnitude. M = c 1 log 10 a + c 2 log 10 d + c 3.