We use a block model to estimate a suite of kinematically consistent
fault slip rates and use these rates to calculate surface strain rates
analytically using elastic dislocation theory in a homogeneous elastic
half space.  The model is subset of a western U.S. block model
geodetically constrained by a combination of the SCEC CMM 3.0,
McClusky ECSZ, Hammond Walker Lane, McCaffrey Pacific NW, d'Alessio
Bay Area, and PBO velocity fields.  These fields are combined using a
6-parameter (rotation and translation) estimator that minimizes
residual velocities at collocated stations.  In southern California,
the block geometry is based on the Plesch et al. CFM-R and features
dipping faults in the greater Los Angeles region, which yield
intricate surface strain rate patterns.  The model features fully
coupled (interseismically locked from the surface to locking depth)
faults everywhere except near Parkfield, along the creeping segment of
the San Andreas fault, and on the Cascadia subduction zone.  In these
regions, we solve for smoothly varying slip on surfaces parametrized
using triangular dislocation elements.  In addition to producing a
surface strain rate field, this approach allows for the analytic
determination of strain and stressing rates at arbitrary depths and
resolved on geometrically complex fault surfaces.

Jack Loveless 
March 15, 2010