Present-Day Rates of Deformation Across the Southern Walker Lane From a Densified Regional GPS Network

The Walker Lane is a diffuse region of right-lateral shear in western Nevada and eastern California that accommodates ~25% (9.3 ± 0.2 mm/yr) of the relative motion between the Pacific and North American plates. The region is characterized by discontinuous NNW-trending right-lateral strike-slip faults, and NE-trending, down-to-the-NW normal faults. The late Quaternary cumulative slip across the southern Walker Lane is only 1/3 the observed regional geodetic rate of right-lateral shear. We address this discrepancy between geologic and modern geodetic rates by installing and surveying a denser network of GPS monuments than previously existed. The higher spatial resolution will allow us to better define deformation rates in this complex tectonic setting. Our GPS data will be combined with accompanying fault kinematic and geochronologic data to determine deformation rates across multiple time scales, from late Quaternary to the present. We conducted a campaign GPS survey covering approximately 10,000 square kilometers encompassing the White Mountains, Fish Lake Valley, Clayton Valley, and the Silver Peak Range. We occupied 23 sites, including 10 newly installed monuments, which are spaced approximately 15-20 km apart. The existing sites used in this survey include the UNR-NEARNET sites, as well as a number of other campaign networks archived at UNAVCO. Stations with the longest history (including sites first surveyed as early as 1992) are expected to yield the most accurate results, while newer sites will help identify spatial patterns of strain partitioning. Monuments will be reoccupied annually and combined with past campaign survey data to determine modern crustal velocities. Initial results from this survey will be presented, which have important implications for understanding strain distribution along this important segment of the Pacific-North America boundary.