Conveners: Terry Tullis, Michael Barall, Jim Dieterich, Ned Field, and Scott Marshall

SUMMARY: The SCEC Community Fault Model (CFM) is the most detailed description of the geometry of faults in California. As such it is the logical fault description to be used by future increasingly detailed simulations of long historic earthquake sequences. However, several problems arise in trying to use the CFM in Earthquake Simulators. The purpose of this workshop is to discuss these problems and potential solutions to them by a small and diverse group of specialists in order to define how and by whom the CFM can be made useful for Earthquake Simulators. An additional intent is to define a process by which future updates to the CFM can be easily made usable by Earthquake Simulators.

Among the problems to be solved are the following:

• How best to create CFM versions that involve roughly equal-sized and equant-shaped elements and whether grids should be created having triangular elements, rectangular elements, or both.
• The top edges of the faults in the CFM follow actual topography, but Earthquake Simulators require an upper planar surface on a half-space, so a version of the CFM needs to be created in which the topography is somehow flattened.
• The CFM contains fault geometry, but does not have either slip rates or slip rakes, both of which are needed by Earthquake Simulators which currently are loaded by back slip. Some method is needed to assign slip rates and rakes for the many faults having no such data and also to reconcile the many instances where finding a simple correspondence between the faults included in the CFM and those included in UCERF3 for which slip-rate and slip-rake data do exist.

The hope is that from this workshop will emerge:

• A consensus as to the best way to solve these problems
• A team of individuals who will agree to do collaborate via one or more SCEC proposals to do the required work
• An approach is developed so that once an initial CFM-EQSIM is created it can easily be updated as improvements are made to the CFM

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SUNDAY, SEPTEMBER 10, 2017

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