UC San Diego

Improved near‐field measurements of earthquake slip and deformation patterns have the potential for expanding our understanding of fault behavior and the relationship of active faulting to topography. Current techniques for obtaining these measurements—including field observation, Global Navigation Satellite Systems displacement estimation, and optical or radar remote sensing—have limitations that can be mitigated by the inclusion of results from differential airborne Light Detection and Ranging (LiDAR) analysis of the rupture zone. The 2005 airborne LiDAR survey of the southern San Andreas, San Jacinto, and Banning faults (the B4 survey) mapped 1100 km of the most seismically active fault systems in southern California for the purpose of providing a baseline for determining slip from a future earthquake. We used the B4 survey to develop a processing algorithm that yields rapid estimates of near‐fault ground deformation using simultaneous cross correlation of both topography and backscatter intensity from pre‐earthquake and simulated postearthquake LiDAR datasets. We show robust recovery of the direction and magnitude of an applied synthetic slip of 5 m in the horizontal and 0.5 m in the vertical within our area of study, with clear discrimination between areas with and without applied slip. We also successfully recovered more complex deformation from a modeled fault stepover in the same study area. Our results indicate that we should be able to recover slip to accuracies of better than 20 cm in the horizontal and 1 cm in the vertical, at a spatial resolution of ≤15  m for LiDAR datasets with sample densities as low as 0.5  points/m².