Microtremor Horizontal-to-Vertical Spectral Ratio (mHVSR) Data Collection at Searles Lake, 2023

The Searles Valley Basin consists of a large endorheic dry lake which contains sediments such as Borax and rock salt, which formed around the late quaternary period. This lakebed exhibited surface manifestation of liquefaction in the form of sand boils in different areas around the lake, following the Ridgecrest Earthquake sequence (RES) on July 4-5, 2019. In an effort to better understand amplification of earthquake ground motions at the site, microtremor Horizontal-to-Vertical-Spectral-Ratios(mHVSR) surveys were performed. The information that these surveys provide can give us insight on site resonances which are anticipated to be significant due to large impedance contrasts. Moreover, we can better understand the geology when multiple surveys are evaluated at different areas around the site. Collaborative research between the University of California, Los Angeles (UCLA) and University of Southern California (USC) has performed mHVSR surveys at 5 sites in the lakebed, close to the sand boils which occurred after the RES. The HVSR curves developed using this dataset may be accessed in the United States Community Shear-Wave Velocity (VS) Profile Database (PDB) (https://uclageo.com/VPDB/). This work was supported by the United States Geological Survey under contract G22AP00320.