INTERSEISMIC DEFORMATION OF THE SAN BERNARDINO REGION FROM GEOLOGICALLY BASED MODELS

Investigation of the active faults in the San Bernardino region requires three-dimensional models that can simulate the complex, non-planar intersecting active fault surfaces. Rather than directly inverting for slip along highly simplified fault surfaces, we use a two-stage approach. First we simulate geologic time-scale deformation and then we use these results to produce interseismic models. Geologic timescale numerical models with 4 km resolution produce good match to geologic slip rates collected in the region. In the interseismic model, slip from the geologic model is prescribed below the locking depth and faults are bonded above the locking depth. The model predicted surface velocities are compared with geodetic velocities from ~80 stations in the region. In some areas the predicted velocities very closely match those of GPS stations in the area. Residuals between the model and data velocities may reflect heterogeneous basement material, inaccurate fault surface representation or inaccurate tectonic boundary conditions.