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Published January 2009 | Published
Journal Article Open

The SCEC/USGS Dynamic Earthquake Rupture Code Verification Exercise

Abstract

Numerical simulations of earthquake rupture dynamics are now common, yet it has been difficult to test the validity of thesesimulations because there have been few field observations and no analytic solutions with which to compare the results. This paper describes the Southern California Earthquake Center/U.S. Geological Surve(SCEC/USGS) Dynamic Earthquake Rupture Code Verification Exercise, where codes that simulate spontaneous rupture dynamics in three dimensions are evaluated and the results produced by these codes are compared using Web-based tools. This is the first time that a broad and rigorous examination of numerous spontaneous rupture codes has been performed—a significant advance in this science. The automated process developed to attain this achievement provides for a future where testing of codes is easily accomplished. Scientists who use computer simulations to understand earthquakes utilize a range of techniques. Most of these assume that earthquakes are caused by slip at depth on faults in the Earth, but hereafter the strategies vary. Among the methods used in earthquake mechanics studies are kinematic approaches and dynamic approaches. The kinematic approach uses a computer code that prescribes the spatial and temporal evolution of slip on the causative fault (or faults). These types of simulations are very helpful, especially since they can be used in seismic data inversions to relate the ground motions recorded in the field to slip on the fault(s) at depth. However, these kinematic solutions generally provide no insight into the physics driving the fault slip or information about why the involved fault(s) slipped that much (or that little). In other words, these kinematic solutions may lack information about the physical dynamics of earthquake rupture that will be most helpful in forecasting future events. To help address this issue, some researchers use computer codes to numerically simulate earthquakes and construct dynamic, spontaneous rupture (hereafter called "spontaneous rupture") solutions. For these types of numerical simulations, rather than prescribing the slip function at each location on the fault(s), just the friction constitutive properties and initial stress conditions are prescribed. The subsequent stresses and fault slip spontaneously evolve over time as part of the elasto-dynamic solution. Therefore, spontaneous rupture computer simulations of earthquakes allow us to include everything that we know, or think that we know, about earthquake dynamics and to test these ideas against earthquake observations.

Additional Information

© 2009 Seismological Society of America. Joe Andrews has thoughtfully contributed to our code comparison exercise in many ways, including by improving our benchmark descriptions. Funding for the Rupture Dynamics Code Verification Exercise has come from the Southern California Earthquake Center (funded by NSF Cooperative Agreements EAR-0106924, EAR-0529922, and USGS Cooperative Agreements 02HQAG0008, 07HQAG0008), internal USGS Earthquake Hazards Program funds, and the U.S. Department of Energy/Pacific Gas and Electric Extreme Ground Motions project. Thanks to Tom Jordan, Norm Abrahamson, Tom Hanks, and Paul Somerville for their support of this project, and thanks to Phil Maechling for graciously helping us with the logistics of the code-validation Web site. This manuscript benefited from helpful USGS internal reviews by Tom Hanks and Nick Beeler and from the comments of an anonymous SRL reviewer. This is SCEC Contribution #1184.

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Created:
August 20, 2023
Modified:
October 17, 2023