Highly Variable Latest Pleistocene‐Holocene Incremental Slip Rates on the Awatere Fault at Saxton River, South Island, New Zealand, Revealed by Lidar Mapping and Luminescence Dating

Abstract

AbstractGeomorphic mapping using high‐resolution lidar imagery and luminescence dating reveal highly variable incremental Holocene‐latest Pleistocene slip rates at the well‐known Saxton River site along the Awatere fault, a dextral strike‐slip fault in the Marlborough Fault System, South Island, New Zealand. Using lidar and field observations, we measured seven fault offsets recorded by fluvial terraces and bedrock markers. Improved dating of the offsets is provided by post‐IR‐IRSL225 luminescence ages. Incremental slip rates varied from <2 mm/yr to >15 mm/yr over intervals of thousands of years and tens of meters of slip, demonstrating order‐of‐magnitude temporal variations in rate at a single site. These observations have basic implications for earthquake fault behavior, lithospheric mechanics, discrepancies between geodetic and geologic slip rates, and probabilistic seismic hazard assessment.