Neotectonic assessment of the southern Wassuk Range, western Nevada

Abstract

Active deformation across western North America is distributed across a broad zone spanning from the San Andreas fault system to the Basin and Range Province. The Wassuk Range fault zone (WRFZ), located within the Walker Lane deformation belt of the western Basin and Range, is a N- to NNW-striking normal fault system. With its oblique orientation to the wide-scale, NW-trending shear between Pacific and North American plates, it demonstrates a transtensional regime. The Whiskey Flat study area (southern WRFZ) corresponds with east-dipping, late Quaternary fault scarps ([tilde] 1-7 meters) along the range front. Seismic and photogrammetric methods were used to examine underlying geometry and fault scarp morphology. Through these imaging techniques, fault scarp degradation modeling assessed the kinematic evolution and longterm slip rate of [tilde] 0.10-0.36 mm/yr, accommodating 0.49-1.4 mm/yr of E-W extension. Significantly, this extension rate is slightly faster than northern and central segments of the Wassuk Range. Holocene earthquakes are estimated to have occurred between 687 and 3774 years ago with magnitudes that range from 6.9 to 7.1. In addition, seismic refraction imaging reveals a potential asymmetric half-graben formation, supporting the idea of a dominant normal fault system that aligns with the broad, NW-trending, rightlateral shear of the Walker Lane and associating plate boundaries. This study demonstrates how structural evolution, neotectonic activity, and future deformation can be gleaned from seismic imaging techniques and numerical models of landscape morphology.