“…To derive a source model and corresponding uncertainties for the South Napa earthquake, we begin by jointly inverting the GPS and downsampled InSAR observations for the location (longitude, latitude, and depth), orientation (strike, dip, and rake), and dimensions (along-strike length and down-dip width) of a single-fault patch with homogeneous slip embedded in a homogeneous elastic half-space using the neighborhood algorithm (Okada, 1992;Sambridge, 1999). We do not use seismic event location information (i.e., hypocenter) to precondition the inversion as earthquakes in other locations globally may be mislocated by tens of kilometers (e.g., Elliott et al, 2010;Devlin et al, 2012;Barnhart et al, 2013). Event moment tensors variably indicate the ruptured fault dipped steeply to the west or east (http://earthquake.usgs.gov/earthquakes/ eventpage/nc72282711#scientific_moment-tensor; last accessed December 2014), so we allow the neighborhood algorithm to sample both dip domains, searching over a broad range of strike, dip, and rake within each region of model space.…”