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Earthquake Statistics Gutenberg-Richter relation. Frequency-Magnitude relation b is an important parameter that varies in time and space ranging around 1 a accounts for the background seismicity rate. Frequency-magnitude relation from seismic moment. Aftershocks.
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Earthquake StatisticsGutenberg-Richter relation Frequency-Magnitude relation b is an important parameter that varies in time and space ranging around 1 a accounts for the background seismicity rate
Aftershocks Aftershock decay rate follows the OMORI law K is the productivity p is close to 1 c account for magnitude completness
3 Omori (1894) 1891 Nobi Earthquake of M8.1
4 Utsu (1961) The Omori-Utsu formula for aftershock decay rate t : Elapsed time from the mainshock K,c,p : constant parameters
Dieterich ‘94 model close to failure far from failure background seismicity Aftershocks occur on faults close to failure. 100 100 80 80 60 60 sec-1x10-7 40 40 20 20 rate (events/time) perturbed seismicity time
INGV 1992 Landers Earthquake r(x,y) m(x,y) reference background
clock-advance t0 Single Fault : probability of failure after a stress step ‘Permanent’ Probability P(telapsed< t <telapsed+Dt) = = ∫ f(t) dt telapsed+Dt probability density telapsed time 0 telapsed telapsed+Dt previous earthquake Clock-advances shorten the mean recurrence time, increasing the probability.