Constraints on the Quaternary fault offset history along the Benton Springs right-lateral strike-slip fault, West-Central Nevada

Timothy John Daniel

Abstract


The Walker Lane is a ~700 km zone of strike-slip and normal faults that extend southward from northeastern California, through western Nevada, and into eastern California. The Walker Lane is important geologically because it accommodates ~25% of the total movement between the Pacific and North American tectonic plates, the rest being accommodated mostly by the San Andreas fault. While the Walker Lane has been the focus of much research, the evolution of this zone is still unclear and has significant implications for the tectonic evolution of this plate boundary system. Some of this uncertainty comes from the lack of constraints as to the amount and rate of fault displacement, specifically in the central Walker Lane, Nevada. This study utilized field mapping of fault scarps and offset alluvial features combined with detailed surveys of these offset features using Terrestrial Laser Scanning (TLS) to document the magnitude of Quaternary fault offset along a section of the Benton Springs right-lateral strike-slip fault within the central Walker Lane. TLS derived digital elevation models (DEMs) were used to generate hillshade and slope maps which were used to precisely measure the magnitude of the offset by back-slipping and reconstructing offset streams using the published MATLAB GUI, LaDiCaoz. Our results indicate that this portion of the fault records right lateral fault offset magnitudes of ~35, 33, 22, 10, 7, 3, and 1 m. The ~1 m offset likely resulted from the most recent earthquake, while the others accumulated from multiple earthquakes. The offset amount from the last earthquake, combined with offset amounts from other studies along this fault were used to estimate the Richter magnitude of the last earthquake, which equates to a magnitude in the range of 6.1 and 7.1.


Keywords


Walker Lane; Terrestrial Laser Scanning; Strike-slip fault offset measurement

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