Active faulting in the Klamath Mountains Province revealed by lidar data

Ryan Lynch, & Michael E. Oskin

Submitted September 7, 2025, SCEC Contribution #14334, 2025 SCEC Annual Meeting Poster #TBD

The Klamath Mountains Province (KMP) in northwestern California, which lies at the intersection of San Andreas transform motion, Cascadian subduction, and Basin and Range extension, has long been considered tectonically rigid due to the absence of mapped active faults in the region. However, the relatively weak rheology and geodetically observed contraction across the KMP indicate that the region should be actively deforming. This study presents a new analysis of high-resolution lidar data to show that the KMP is transected by active faults, which have gone unnoticed until now because the region is elevated, eroding, and densely forested. Newly discovered normal, dextral strike-slip, and reverse faults provide evidence that the KMP acts as a rheologically weak, diffuse boundary zone accommodating varying styles of deformation due to the complex tectonic forces acting on its margins. Future application of single-grain feldspar IRSL dating to fault-bounded sedimentary deposits will quantify fault slip rates and constrain the rate and style of active deformation in the KMP. These findings will improve regional seismic hazard assessments and provide key input to geodynamic models of the broader plate-boundary system.

Key Words
lidar, tectonic, slip rates, geochronology

Citation
Lynch, R., & Oskin, M. E. (2025, 09). Active faulting in the Klamath Mountains Province revealed by lidar data. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology