EPS 20 Lecture Notes - Lecture 12: Nuclear Explosion, Body Wave Magnitude, Nonogram
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Subjective measure (depends on types of buildings0. Need a measure of the size of an earthquake. Why magnitude? single number to measure an earthquake initially, a measure of the amplitude of ground shaken with respect to a reference event: richter magnitude: magni- tude is log10 of the maximum amplitude recorded on a. Wood-anderson seismome- ter at 100 km from the epi- center (we do not use this anymore) Take log of amplitude that was observed and correct for difference. Other types of magnitude: body wave magnitude: mb, surface wave magnitude: ms. Ms and mb estimates are usually different for a given earthquake: mb measures the amplitude of the p-wave, ms measures the amplitude of the surface wave. Nuclear explosion do not excite surface waves so we can determine by using ms and. Mb to see if an earthquake or an explosion occurred (also tell by depth)