Beneath a depth of 2 km the SAF shows no evidence of having a low resistivity. This indicates that the fault zone contains limited fluids. Electrical resistivity model of the San Andreas Fault at Carrizo Plains. Ticks indicate measurement locations. The model was derived by inversion of tensor magnetotelluric and is the smoothest model that fits the data.
Lower panel shows a structural interpretation.
An identical analysis was applied to the data collected at Parkfield, and the best fitting resistivity model is shown in Figure 2. Note that the shorter profile has limited our depth of investigation to approximately 2 km. The structure at this location is very different to that at Carrizo Plain. This is overlain by approximately 700 metres of sediments from the Paso-Robles formation. East of the fault are less resistive Tertiary and Franciscan rocks.