The Origin of the Earthquake Inter-Event Time Distribution
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Transcript of The Origin of the Earthquake Inter-Event Time Distribution
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The Origin of the Earthquake Inter-Event Time Distribution
Sarah Touati, Mark Naylor, Ian Main
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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
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Universal gamma distribution?
Corral, A., PHYSICAL REVIEW E 68, 035102(R) (2003)
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Examples of IET distributions
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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
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ETAS model
)|( tHt
ttip
i
MM
i
i
ctteK
:
)(
)(
10
time
Magnitudes follow Gutenberg-Richter distribution and are independent of history
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ETAS IET distributions
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Origin of the IET distribution
time
correlated
uncorrelated
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Origin of the IET distribution
μ = 0.0029 μ = 0.74 μ = 11
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Rescaled ETAS IET distributions
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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