Annual Meeting - SCEC.org

Poster Abstracts | Group 1 – ExGM
to be unrealistically low. The experiments have weakly pressure dependent strength loss and large
fracture energy which extrapolate to very low slip rate and particle velocity at crustal conditions.
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THE SCEC/USGS 3D RUPTURE DYNAMICS CODE COMPARISON EXERCISE Harris
RA, Barall M, Archuleta RJ, Aagaard B, Ampuero J, Andrews DJ, Cruz-Atienza VM, Dalguer LA,
Day SM, Duan B, Dunham EM, Ely GP, Kaneko Y, Kase Y, Lapusta N, Liu Y, Ma S, Oglesby DD,
Olsen KB, Pitarka A, Song S, and Templeton EL
Computer simulations of earthquake source rupture physics started three decades ago, with a few
researchers developing and using their own methods to solve problems of mostly theoretical
interest. In contrast, in current times numerous spontaneous rupture computer codes are now
being developed and used by researchers around the world, and the results are starting to be used
in earthquake hazard assessment, for both seismological and engineering applications. Since most
of the problems simulated using these numerical approaches have no analytic solutions, it is
essential to compare, verify, and validate the various versions of this research tool. To this end, a
collaborative project of the Southern California Earthquake Center, that has received some funding
from the DOE Extreme Ground Motion project, has been underway. We started with the basic
problem of earthquake nucleation and spontaneous rupture propagation on a vertical strike-slip
fault in a homogeneous material and subsequently moved on to problems with slightly more
heterogeneous stresses and with differing material properties on opposite sides of the fault. Our
next exercises are 1) the case of rupture on a dipping fault, which is relevant to the Yucca Mountain
fault-rupture scenarios, and 2) the case of rate-weakening friction, rather than the slip-weakening
friction used in most of our previous exercises. With SCEC and DOE support, we have a website
that enables easier comparisons of the results among the modelers, and also supplies information
about the benchmarks and codes. Our overall objective is a complete understanding of the
simulation methods and their ability to faithfully implement our assumptions about earthquake
rupture physics and calculate the resulting ground motion.
108 | Southern California Earthquake Center