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The Origin of the Earthquake Inter-Event Time Distribution. Sarah Touati, Mark Naylor, Ian Main. Why inter-event time distributions?. They characterise the temporal behaviour of a seismic region Understanding them will afford insight into seismic patterns
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The Origin of the Earthquake Inter-Event Time Distribution Sarah Touati, Mark Naylor, Ian Main
Why inter-event time distributions? • They characterise the temporal behaviour of a seismic region • Understanding them will afford insight into seismic patterns • Recognising and understanding their features will allow validation of physical models of seismicity
Universal gamma distribution? Corral, A., PHYSICAL REVIEW E 68, 035102(R) (2003)
ETAS model • Statistical point-process model for earthquake occurrence • Inspired by population models in epidemiology immigration birth death spontaneous events triggering of events not used
ETAS model magnitude time Magnitudes follow Gutenberg-Richter distribution and are independent of history
Origin of the IET distribution uncorrelated magnitude correlated time
Origin of the IET distribution μ = 0.0029 μ = 0.74 μ = 11
Conclusions • Earthquake inter-event times follow a mixture distribution, not a gamma distribution • Intervals between correlated events are gamma-distributed • Intervals between uncorrelated events are Poisson-distributed • The distribution cannot be fully universal