Application of Remote Sensing Data to Correlating Alluvial Fans along the southern San Andreas Fault at Devers Hill, CA

The overall rate of motion along the Pacific-North American plate boundary is well constrained from GPS data, but the distribution of this motion among the various faults of the San Andreas Fault System is not well understood, particularly in southern California. An especially complex and poorly understood part of the southern San Andreas Fault (sSAF) in southern California is along the Banning strand at the northwest end of the Coachella Valley near San Gorgonio Pass. Presently, slip rates for this part of the sSAF are entirely unconstrained, but are critical to earthquake forecasting efforts. Here we examine several displaced features along the Banning strand of the sSAF at a site known as Devers Hill, focusing primarily on Quaternary alluvial fans of varying ages. A first step in accurately deriving a slip rate for this location is to correlate these fan segments across the fault. To compare and correlate different offset features, we use several forms of remote sensing, including 0.5-m-resolution LiDAR data from the B4 dataset, 2- to 5-m-resolution MODIS/ASTER (MASTER) multispectral imagery, and high-resolution aerial photographs. These datasets allow us to quantitatively determine a) surface roughness, b) drainage density and morphology, and c) boulder distributions, sizes and concentrations. The remote sensing data we collect will be compared to independent correlations of offset features based on cosmogenic Be-10 dating of boulder tops and cobbles, as well as field-based measurements of surface characteristics too subtle for remote sensing imagery (see Gold et al. abstract submitted to Session T009, this meeting). We also use the remote-sensing data sets to investigate other types of offset features at other sites along the sSAF.