Progress in Linking Earthquakes to Seismogenic Faults in the Lake Tahoe-Truckee Area, California and Nevada

REED, T. H., Baylor University, Waco, Texas, USA,; LINDSAY, R. D., Baylor University, Waco, Texas, USA,; CRONIN, V. S., Baylor University, Waco, Texas, USA,; SVERDRUP, K. A., University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA,

Preliminary work by Lindsay and Cronin used the Seismo-Lineament Analysis Method (SLAM; Cronin and others, 2008, Env & Eng Geol 14[3], 199-219) and focal mechanism solutions from 29 earthquakes in an effort to spatially correlate earthquakes with the faults that generated them in the northern Lake Tahoe-Truckee area of California and Nevada. The earthquakes used in the preliminary study included the largest reported from the area (1966 Truckee M 6.0) and earthquakes with magnitudes of 3 or greater that occurred between 1980 and late 2009. Tentative spatial correlation was noted between one or more earthquakes and several known or suspected faults, including the Dog Valley fault zone (fz), Stateline-North Tahoe fz, West Tahoe-Dollar Point fz, Incline Village fault, Polaris fault and the hypothetical Agate Bay fault. Two other trends were identified along which seismo-lineaments coincide with geomorphic lineaments that might have developed during Quaternary displacement along previously unrecognized faults.

The current study includes additional earthquakes, uses improved focal-mechanism solutions when available, includes spatial trend analysis of hypocenters for events that lack focal mechanism solutions, utilizes an improved version of the SLAM computer code operating on higher-resolution DEM data, and references additional known/suspected Quaternary faults compared with the initial study. The initial study used single-event focal locations; the current study is using relocated foci (e.g., Jordan and Sverdrup, 1981, BSSA 71, 1105-1130). We also use GPS geodetic data from EarthScope's Plate Boundary Observatory to better understand the current horizontal strain field in the North Tahoe area. Synthesis of preliminary results with prior work indicates that the study area is subject to earthquakes on N-striking E-dipping normal faults, NW-striking dextral faults and their conjugates -- NE-striking sinistral faults.

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