ELVIS: Mapping Las Vegas Valley Basin Resonance utilizing HVSR methods

Delton A. Samuel, Heather A. Ford, Joseph Byrnes, & Rufus D. Catchings

Submitted August 30, 2026, SCEC Contribution #15536, 2026 SCEC Annual Meeting Poster #TBD

The population of the Las Vegas Valley Basin (LVVB) in Nevada exceeds 1.7 million people and is exposed to significant seismic hazards within the LVVB, where its shallow subsurface is known to be composed of 1 to 5 km of clastic fill. The seismotectonics of LVVB is also complicated by a pull-apart transtensional regime; thus, its variation in sediment thickness has the potential to strongly influence a site dominant resonance frequency (f0) and the resulting severity in ground shaking from large earthquakes. In June and July 2025, investigators from the University of California-Riverside, University of Texas at Dallas, and the United States Geological Survey, jointly conducted a seismic experiment known as “Evaluating Las Vegas’ Internal Seismicity” (ELVIS) to record ambient noise and earthquakes in the basin. ELVIS includes a network of 91 three-component (5 Hz) nodal seismometers that were spread across the LVVB at an average spacing of 4 km apart. We used the high sample rate (100 Hz) and dense spacing (4 km) of the resulting ELVIS seismic data to map variations in fd across the LVVB. We applied the Fourier-transform method to each component (north, east, and vertical) and computed the Horizontal Vertical Spectral Ratio (HVSR) by merging the two horizontal components into a single spectrum and estimating their geometric mean. We apply Konno-Ohmachi smoothing to all components, prior to dividing the horizontal spectrum by the vertical spectrum. We employ the technique to 60-second time windows between 12:00 am and 4:00 am for 30 days and stack results to minimize anthropogenic noise contamination and to capture wavelengths for resolving f0. We observe lower f0 values (~0.2 to 0.8 Hz) near the base of Frenchman Mountain (FM), where the basin is known to be the deepest, and we observe higher f0 values (up to ~5 Hz) along the edges of the Basin where it is shallower near uplifted basement. Thus, we speculate stronger shaking would occur in the FM area from future large earthquakes than other parts of the basin. Our results are consistent with previous site response studies and the known basin geometry, further corroborating the variations in our calculated f0 spatial patterns.

Key Words
Basin, resonance, HVSR, spatial

Citation
Samuel, D. A., Ford, H. A., Byrnes, J., & Catchings, R. D. (2026, 08). ELVIS: Mapping Las Vegas Valley Basin Resonance utilizing HVSR methods. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology