Lidar mapping and luminescence dating reveal highly variable latest Pleistocene-Holocene slip rates on the Awatere fault at Saxton River, South Island, New Zealand

Robert Zinke, James F. Dolan, Russ J. Van Dissen, Ed J. Rhodes, & Christopher P. McGuire

Submitted August 15, 2016, SCEC Contribution #6951, 2016 SCEC Annual Meeting Poster #100

We use high-resolution lidar micro-topographic data and luminescence dating to constrain incremental Holocene–late Pleistocene slip rates at the well-known Saxton River site along the Awatere fault, a primary dextral strike-slip fault in the Marlborough Fault System, South Island, New Zealand. Field work and mapping using lidar-derived topography yields revised measurements of seven fault offsets recorded by fluvial terrace risers, channels, and bedrock features. Improved dating of those features is provided by stratigraphically informed analysis of >20 post-IR50-IRSL225 luminescence ages. Monte Carlo analysis is used to derive robust determinations of incremental slip rates. Our results show definitively that, far from being constant, incremental Awatere fault slip rates (averaged over multiple millennia and 10’s of m of slip) have varied by more than an order of magnitude since latest Pleistocene time. These observations have major implications for earthquake occurrence, plate boundary lithosphere behavior, and probabilistic seismic hazard assessment.

Key Words
fault slip rates, slip rate variability

Citation
Zinke, R., Dolan, J. F., Van Dissen, R. J., Rhodes, E. J., & McGuire, C. P. (2016, 08). Lidar mapping and luminescence dating reveal highly variable latest Pleistocene-Holocene slip rates on the Awatere fault at Saxton River, South Island, New Zealand. Poster Presentation at 2016 SCEC Annual Meeting.


Related Projects & Working Groups
Earthquake Geology