PRELIMINARY 2.5-D GRAVITY MODELS FROM LEMMON VALLEY AND THE TAHOE-RENO INDUSTRIAL CENTER, WESTERN NEVADA

Whereas earthquakes cause more death and destruction each year than any other type of natural disaster, those hazards can be reduced if we can forecast the amount and distribution of shaking an area will experience during an earthquake. A detailed understanding of subsurface conditions, including overall basin shape and density contrasts, is critical to understanding how seismic waves will propagate through the subsurface. Accurate seismic hazard forecasting is especially important in areas of rapid expansion and critical infrastructure, as an accurate assessment of shaking hazard is crucial to designing appropriate earthquake mitigation in roads, buildings, bridges, and other structures.

The area surrounding Reno, NV is undergoing rapid housing and industrial expansion. Two of these areas, Lemmon Valley and the Tahoe-Reno Industrial Center (TRIC) north and east of Reno, respectively, as seeing rapid industrial warehouse, factory, and data center expansion. Additionally, critical infrastructure is present, including the Stead airport and Tracy-Clark power plant and major highways and railways. The Reno metro area is tectonically complex, sitting at the intersection of the western Basin and Range and northern Walker Lane tectonic provinces. Much is known about the Reno basin, but many of the other valleys, including Lemmon and TRIC are relatively understudied. Therefore, we collected and modeled several gravity transects in Lemmon Valley and the TRIC to improve our understanding of basin shape and density contrasts to improve seismic hazard models.

We collected 310 high-precision gravity measurements along nine transects totaling 75 km in length. Combined with over 2,400 existing gravity measurements in the Reno area, those data were reduced to generate full Bouguer anomaly maps. From these we are generating six cross-sections (three in each basin) to model basin depth, shape, and fill density. These cross-sections will be further constrained by well log data and integrated with shear-wave velocity models to improve our understanding of seismic wave propagation and shaking hazard in Lemmon Valley and the TRIC.