Revised and Improved Fault Maps of Washoe County, Nevada using Light Detecting and Ranging (LiDAR) Imagery

Abstract:

A new Light Detection and Ranging (LiDAR) survey images the fault network of Truckee Meadows region of western Nevada, including the Reno/Sparks metropolitan area in Washoe County. The airborne LiDAR imagery (1485 sq. km) is being used to create high quality bare-earth digital elevation models that were previously unattainable in vegetated, populated or alpine terrain. LiDAR gives us an opportunity to improve fault maps that may be outdated or incomplete in the area. Here we show LiDAR imagery of a large section of Washoe County and highlight areas where this imagery may be useful in revising current fault maps.

Conflicting stress regimes, with strike-slip regions overlapping extensional domains in the Walker Lane Deformation Belt, complicate regional tectonics of Washoe County. In this region east of the Sierra Nevada batholith, approximately 20-25% of Pacific–North American plate motion (mostly right-lateral shear) is accommodated along the Walker Lane. There is ample evidence of Magnitude 6-7 earthquakes in or surrounding the Truckee Meadows region as recently as the late 1800s and it is possible that earthquakes of this size may occur here in the near future. Accurate mapping of faults and associated earthquake hazards in populated areas is critically important for earthquake mitigation and preparedness, and furthers our understanding of regional tectonics. The new LiDAR data confirms the presence of many previously mapped faults, simplifies areas that may be presently over-complicated by current maps, and identifies faults that were previously unmapped. Current and future research will also focus on dating of glacial outwash terraces and alluvial fans, particularly in the Mogul area and Mt. Rose pediment. Coupled with comprehensive fault maps and displacement measurements improved by this new LiDAR dataset, these data may allow researchers to get more accurate slip rate estimates on faults in this region, and may support the hypothesis that some faults in the Washoe County region are more active than previously reported.