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Session: Advances in Intraplate Earthquake Geology

Type: Oral

Date: 4/24/2019

Time: 08:45 AM

Room: Vashon

Towards Time-Dependent Modelling of Episodic Earthquake Occurrence on Intraplate Faults

Increasing volumes of paleoseismological evidence suggest that the occurrence of large earthquakes on many, if not most, faults in low seismicity regions clusters in time. Faults appear to have a few large earthquakes within a relatively short period of time followed by long periods of quiescence. This contrasts with the assumption that earthquakes are Poisson distributed in time that typically underpins probabilistic seismic hazard assessment. Therefore a key challenge for hazard assessment for intraplate regions lies in describing the underlying temporal distribution of earthquake occurrence on such faults. In this study, relationships between clustering behaviour and the long-term deformation rate are explored using a global compilation of paleoseismic data from low-seismicity regions. Preliminary results suggest that clustering scales with the long-term deformation rate, such that faults with slower long-term slip rates have longer quiescent periods. The timing of the most recent earthquake gives information on the current state of the fault (active, quiescent or transitional) and can be used to make time-dependent estimates of the present day probability of a fault rupturing. However, predictive models are challenged by the limitations of paleoseismic records in intraplate regions. This includes uncertainty in resolving individual earthquakes in the record and dating uncertainties, which in turn contribute to uncertain and/or conflicting interpretations of the event chronology. In our present work we are using a Bayesian framework to test alternative time-dependent and independent distributions for earthquake inter-event times, with full consideration of the uncertainty inherent to paleoseismic chronologies.

Presenting Author: Jonathan D. Griffin

Additional Authors