Poster #119, Stress and Deformation Over Time (SDOT)

Measuring uncertainty in surface strain rates in Southern California using multiple methods and elastic models.

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Poster Presentation

2020 SCEC Annual Meeting, Poster #119, SCEC Contribution #10710
Geodetic data can be used to infer surface strain rates, which are correlated with seismic hazard (e.g. Savage & Simpson, 1997; Bird, 2015). Using strain-rate to infer hazard benefits from making no assumptions about faults; however, challenges remain, especially in areas of diffuse faulting and distributed deformation, where strain rates may include both elastic and inelastic (“off-fault”) contributions (e.g. Johnson, 2013). Due to lack of confidence in off-fault strain rate estimates generated by models of geodetic data, these off-fault rates were not used in UCERF3 or 2014 NSHM hazard calculations. Here we explore uncertainty in computed strain rates arising from the choice of met...hod and from data uncertainty by estimating strain rates in southern California using several different methods and generating conditional realizations of the velocity field using each method to estimate the mean and uncertainty in the total strain rate field. We use the Kostrov method (Savage and Simpson, 1994; Kostrov, 1954) to compute the total moment rate for each simulated strain rate field and show that the total moment rate estimated for southern California estimated using the Kostrov method may exceed that estimated using elastic models by 30% or more (Johnson, 2013; Maurer et al., 2018), consistent with previous results (Johnson, 2013).