Luminescence Age Constraints and Slip Rate Estimates for the Mt. Rose Fault Near Reno, Nevada

Carter W. Dills, Daniel T. Trugman, Rich D. Koehler, Kathleen Rodrigues, & Steven G. Wesnousky

Submitted August 30, 2026, SCEC Contribution #15534, 2026 SCEC Annual Meeting Poster #TBD

We report new chronological constraints on two alluvial fan surfaces offset by the Mt. Rose Fault, a range-bounding normal fault located near Reno, Nevada, derived from infrared stimulated luminescence (IRSL) dating of samples collected from paleoseismic trenches. The Thomas Creek Trailhead study site was chosen for its clearly preserved fault scarps and its favorable topography for estimating vertical displacement. Two pits were excavated into adjacent Quaternary alluvial surfaces crossed by the fault trace: Thomas Creek Soil Pit 1 (TCSP-1) and Soil Pit 2 (TCSP-2), situated on the lower and higher surfaces, respectively. The resulting luminescence chronology places abandonment of the lower surface at roughly 15 ka and the higher surface at 27–29 ka, indicating that both surfaces stabilized during the late Pleistocene: considerably more recently than earlier relative-dating estimates of 100–300 ka derived from regional glacial correlations. Coupling these revised ages with scarp-offset measurements produces a vertical slip-rate estimate of 0.21-0.73 mm/yr and a corresponding dip-slip rate of 0.27-1.45 mm/yr. These refined rates narrow the broad 0.1-5.0 mm/yr range listed in the USGS Quaternary Fault and Fold Database and fall below the 1.5 mm/yr slip rate currently adopted in the National Seismic Hazard Model (NSHM), carrying meaningful implications for reassessing earthquake recurrence intervals along this fault near the Reno - Carson City metropolitan corridor.

Key Words
Paleoseismology, Geochronology, Luminescence Dating, Nevada

Citation
Dills, C. W., Trugman, D. T., Koehler, R. D., Rodrigues, K., & Wesnousky, S. G. (2026, 08). Luminescence Age Constraints and Slip Rate Estimates for the Mt. Rose Fault Near Reno, Nevada. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology