From M8 to CyberShake: Using Large-Scale Numerical Simulations to Improve Seismic Hazard Models

Thomas H. Jordan
Seminar

Abstract. A seismic hazard model computes the probability that earthquake ground motions at a geographic site will exceed some specified shaking intensity during a fixed interval of time. The National Seismic Hazard Model (NSHM), which is regularly updated by the USGS for all U.S. territories, is the basic source of seismological information used by decision-makers at the local, state, and federal levels for earthquake risk assessment, seismic safety engineering, and disaster preparedness. The NSHM is currently limited by uncertainties in long-term earthquake rupture forecasts, the paucity of near-field recordings of large earthquakes, and the variability arising from fault rupture complexity and wave propagation through highly heterogeneous crustal structures. This presentation will describe how large-scale, physics-based simulations of earthquakes can improve seismic hazard mapping by addressing these limitations.
Interdisciplinary teams organized by the Southern California Earthquake Center (SCEC) have used the Oak Ridge and Argonne Leadership Computing Facilities, as well as NSF supercomputers, to model a complete spectrum of earthquakes in Southern California. The M8 production runs on NCCS Jaguar have simulated magnitude-8 earthquakes on the San Andreas fault with 4D outer/inner scale ratios approaching 1017, fully representing the strong seismic shaking from a