Active Faulting in the Northern Walker Lane and Post-Earthquake Reconnaissance in the Central Walker Lane, Nevada and Eastern California
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Authors
De Masi, Conni Leeann
Issue Date
2021
Type
Dissertation
Language
Keywords
Earthquakes , Hazards , Nevada Tectonics , Tectonics , UAV , Walker Lane
Alternative Title
Abstract
The Walker Lane is a region of diverse tectonic activity situated along the Pacific-North American plate boundary. Unmapped and under characterized faults within the northern Walker Lane are associated with large uncertainties in the location and frequency of potential earthquakes in the greater Reno, Nevada metropolitan area. Mapping of primary and secondary earthquake features in post-event studies help understand the location of faulting and amount of damage associated with earthquakes in the central Walker Lane. Two fault systems in the northern Walker Lane are the Petersen Mountain fault located in the North Valleys region of Reno, and the Bonham Ranch fault in the Smoke Creek Desert of Pleistocene Lake Lahontan in the northern Walker Lane. A paleoseismic trench was excavated across the Petersen Mountain fault to document evidence for faulting and determine the timing of earthquake events. Optically stimulated luminescence dating methods were applied to faulted alluvial fan deposits exposed in the trench. For the Bonham Ranch fault, Uncrewed Aerial Vehicle (UAV) flight surveys were conducted in three locations to investigate differences between topographic scarps formed by tectonic displacement and shoreline processes. Cross cutting relations between the different scarp types combined with stratigraphic observations from outcrops were used to assess the timing of tectonic displacement across the fault. Additionally, UAV surveys were conducted during post-earthquake rapid response reconnaissance in the central Walker Lane immediately following the 15 May 2020 M6.4 Monte Cristo, Nevada and 8 July 2021 M6.0 Antelope Valley, California earthquakes. The drone flights assisted ground crews in determining where to look for surface rupture, earthquake secondary effects, and associated damage. These data provided insight into the amount and style of surface deformation immediately following the earthquake events, and the locations of faulting in the central Walker Lane. These studies help answer questions pertaining to the locations and effects of earthquakes in these regions. By incorporating UAV technology into tectonic studies, hi-res aerial images for mapping and Structure From Motion models can be created, and result in a permanent archive of post-earthquake surface damage as well as provide means to measure paleo and modern surface rupture offsets applicable to seismic hazard characterization.