Sarah Minson California Institute of Technology

Sarah E. Minson California Institute of Technology Jessica R. Murray, John O. Langbein, Joan S. Gomberg U.S. Geological Survey

Real-time: EEW Location Mw Shortly thereafter: Network response Better location Better Mw Source mechanism Much, much later: Research/source studies Fault geometry Finite fault slip model Kinematic rupture model

Mw 9.0

Final Gavin Hayes and David Wald

Use Bayesian inference with a conjugate prior to derive: 1.Analytical expression for PDF describing all possible slip distributions 2.Analytical expression for the probability associated with any fault geometry

Assume an epicenter location from seismic EEW Consider the set of faults centered at the epicenter with any strike and dip Build discretized fault with total extent large enough to encompass rupture Only include offsets from stations within expected P-wave range

Seismic EEW GPSGPS PTWCPTWC True Mw Evolution

Best Slip ModelReal-timeUniform Seafloor uplift Fault slip

Real-time finite fault source models require only existing information: EEW location Real-time high-rate GPS streams These models are not limited by computational expense. They are limited by the time it takes for the rupture to grow in size and information about the rupture to propagate

For regions with both dense seismic networks and real-time high-rate GPS, we could have non- saturating magnitudes and finite fault slip distributions (and thus accurate warnings and shaking forecasts) in real-time starting today.