Preliminary Analysis of High-Resolution Seismic Imaging Profiles Acquired Through Reno, Nevada, for Earthquake Hazard Assessment

In support of the Western Basin and Range Community Velocity Model and the proposed Reno-Carson City Urban Seismic Hazard Maps, the U.S. Geological Survey, University of Nevada, Reno, and nees@UTexas, Austin, collaborated in a high-resolution seismic imaging study of the Truckee Meadows basin in Reno and Sparks, Nevada in June 2009. We acquired two seismic reflection profiles to determine basin structure and fault locations in this area. We used the nees@UTexas minivib I vibrator source with a 12-second linear sweep from 15-120 Hz each, and recorded 2-second records on 144 channels with 5-m geophone intervals. One 6.72-km profile followed the Truckee River through downtown Reno east to Rock Boulevard, and a second 3.84-km profile followed Manzanita Lane, about 4.5 km south of the Truckee River. The second profile crossed several previously-mapped faults, including the Virginia Lake fault. Stacked images of both profiles were produced in the field and reveal strong reflections between about 0.2 km and 1.0 km depth. Preliminary interpretation of the Truckee River profile suggests the presence of several possible faults and an eastward-dipping reflection sequence. The Manzanita Lane profile shows reflections across a fault zone with multiple steeply-dipping strands. Additional processing, including pre-stack depth migration, will be performed on these data, and our analysis will incorporate local stratigraphic and structural information, as well as existing borehole data.