ESTIMATING FAULT ZONE MATURITY AT THE PLATE BOUNDARY SCALE USING TEMPLATE MATCHING FOR FAULT SCARP DETECTION AND MORPHOLOGIC DATING

Variation in fault scarp morphologic ages within and between fault zones serves as an important proxy for fault activity on timescales beyond the instrumental record. Regional-scale compilations of these ages where scarps are produced by faults hosted in different lithologies or subject to diverse climatic conditions could reveal patterns in scarp preservation potential and earthquake surface rupture over time. Template matching using topographic curvature shows promise for semi-automatic morphologic dating of degraded fault scarps, successfully detecting scarps where distinct slope breaks are preserved. However, a computationally expensive parameter search and small template window sizes have limited these methods to relatively restricted study areas on the order of 1-10 km² imaged in airborne laser swath mapping (ALSM) data.

As a step towards plate boundary-scale scarp detection and dating, we present a parallel template matching framework suitable for deployment on a cloud computing platform. Testing shows performance improvements in large-scale morphologic dating of fault scarps, enabling efficient processing of large, high-resolution topographic datasets. Preliminary results from the EarthScope Northern California ALSM dataset are compared to detailed field mapping of fault scarps and other geomorphic features. Best-fit template parameters are evaluated along the Olema Valley segment of the San Andreas Fault (SAF) where independent constraints are available from measurements of displacement during the 1906 earthquake and Holocene offsets estimated from paleoseismological trench studies. Sites with fewer constraints, such as the Rodgers Creek Fault and the SAF near Point Arena, are used to assess the potential of large-scale fault scarp dating for studying the rupture behavior and activity of locked or seismically quiescent faults.