SCEC Award Number 13104 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title A Collaborative Project: Comparison, Validation, and Verification of Earthquake Simulators
Investigator(s)
Name Organization
Terry Tullis Brown University Michael Barall Invisible Software Keith Richards-Dinger University of California, Riverside Steve Ward University of California, Santa Cruz John Rundle University of California, Davis Louise Kellogg University of California, Davis
Other Participants Jim Dieterich, UC Riverside
Fred Pollitz, USGS
Donald Turcotte, UC Davis
SCEC Priorities 2, 4, 1 SCEC Groups WGCEP, EFP, FARM
Report Due Date 03/15/2014 Date Report Submitted N/A
Project Abstract
 Simulators help us understand the mechanics of earthquakes. They help us learn whether aspects of earthquakes may be predictable and, if so, how those predictions might be done. For earthquake simulators to be useful however, they must behave in a manner that has elements of reality. Determining how realistic and useful simulator results might be is a difficult task. Toward this end, this project continues a process of comparison and evaluation of a variety of earthquake simulators to gain a better understanding of which features are common to them all, and which features depend strongly upon variable details of input and assumption. The efforts of the Earthquake Simulator Group currently lie in three areas: benchmark test problems, running full statewide simulators, and comparison of results. In 2013 the Group focused on understanding fault-to-fault jumps and beginning to simulate a UCERF3 deformation model. This work is not complete and continues into 2014. Our work has shown that the instrumental, historic, and paleoseismic record is too short to provide a representative sample of the seismic behavior of California in terms of the rate of earthquakes of larger magnitude and the rate of seismic moment.
Intellectual Merit This project offers understanding of the interaction between earthquakes in a large system of faults through physics-based simulations of long series of earthquakes in all of California. The results to date show that the instrumental, historic, and paleoseismic record is too short to provide a representative sample of the seismic behavior of California. These simulations offer the possibility of understanding what are the most important factors determining the temporal and spatial pattern of seismicity.
Broader Impacts The research has shown that the physics-based earthquake simulators produce realistic patterns of seismicity as determined by comparison with observed seismicity over the limited range of observational data. Furthermore the simulations make predictions about the variability of rates of large earthquakes that go beyond the observable historic record. These predictions nevertheless appear to be reasonable and leads many in the community to believe that inclusion of simulator results in future versions of UCERF will offer benefit to society for understanding earthquakes that cannot be provided any other way.
Exemplary Figure Figure 1. Illustration of rupture jumping from one fault to another, using simulator RSQSim, compressional stepover case. The initial rupture occurs on fault section 1, the one shown in the lower left. Fault section 2, shown in the upper right lies 1000 m behind section 1; top of both is at Earth’s surface. The color contours show the maximum slip and the grey contours show the position of the rupture front in one-second intervals. Rupture on section 2 occurs nearly when rupture on section 1 reaches the right end of section 1.

From Keith Richards-Dinger, UCR.