Gravity models from Lemmon Valley, western Nevada, to aid earthquake risk assessment

Accurate community velocity models (CVMs) are critical for understanding and modeling potential earthquake shaking hazards. Those models require an understanding of the depth, geometry, and sediment density within sedimentary basins. We conducted gravity research in Lemmon Valley, Nevada, an area experiencing rapid urban and industrial growth, to help map the Lemmon Valley Basin and to better constrain the local CVM. Raw gravity readings taken at 179 locations along three transects totaling 50 line-km were reduced to a complete Bouguer anomaly for each point. Combining with preexisting gravity data allowed interpolation of these readings across the entire basin and production of 2D and 3D models of the depth to dense bedrock. This model revealed a relatively steep-sided basin in Lemmon Valley bounded by normal faults on both sides. The basin is 5 km long and 2 km wide and extends between 400 and 800 m deep. This newly resolved basin has been added to the CVM for the Reno, Nevada, area. This higher-resolution CVM will allow urban planners, engineers, and architects to use more appropriate earthquake mitigation strategies when designing bridges, buildings, and other structures in this part of western Nevada.