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Paleoseismic Observations along US Highway 50: An Estimate of Net Long-Term Extension across the Basin and Range, Nevada

Koehler, R.D., and Wesnousky, S.G., University of Nevada, Reno, Center for Neotectonic Studies, Mackay School of Mines/169, Reno, NV, 89557-0135, koehler@seismo.unr.edu, stevew@seismo.unr.edu

The recently installed permanent GPS monitoring array of Earthscope is beginning to provide real time measures of strain accumulation across the western United States, as well as, the Basin and Range-Colorado Plateau transition. In the region along US Highway 50 in Nevada and Utah, relatively few paleoseismic studies have been conducted, hindering efforts to compare rates of geodetically measured strain accumulation to rates of strain release by earthquakes. Thus, we document the amount and timing of late Pleistocene displacements along 10 rangefront faults distributed across the region including the Desatoya, Toiyabe, Monitor, Simpson Park, Toquima, Antelope, Fish Creek, Butte, Egan, and Schell Creek Range faults. The data include observations from aerial and surficial geologic mapping, scarp diffusion analyses, soils geomorphology, fault trenching, and compilation of previous studies, and are used to provide an estimate of net long-term extension across the region. The results indicate that long recurrence intervals and slow deformation rates characterize the interior of the Great Basin. Additionally, the amount of strain released by earthquakes (~1 mm/yr) across the region during the late Pleistocene is similar to the rate of short-term geodetically measured strain accumulation. The similarity between geologically and geodetically determined rates of deformation indicate that comprehensive assessment of all active faults in a region is critical to resolving discrepancies between geologic and geodetic studies and understanding seismic hazards.

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Last Modified: 2011 Aug 10

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