This data release documents 43 horizontal-to-vertical spectral ratio (HVSR) passive seismic measurements collected at 24 locations in the Virginia Coastal Plain within Fairfax and Prince William Counties during June and July 2025. The HVSR method uses a three-component seismometer to measure vertical and horizontal components of ambient seismic noise over a frequency range of approximately 0.1 to 50 hertz (Hz). The HVSR method can identify a resonant frequency (f₀) associated with a substantial contrast in shear-wave acoustic impedance between unconsolidated sediments and underlying bedrock. Resonant frequencies are determined from the spectral ratio of the horizontal and vertical components of the seismic data. Most locations included paired measurements, identified by the “_A” and “_B” suffixes, to evaluate the consistency of resonance-frequency measurements. Individual measurements were collected for durations ranging from 20 to 60 minutes. Measurement duration was decided based on the noise contamination present at each site. Noise contamination was qualitatively assessed on site by the proximity of bodies of water, mechanical, or other sources of continuous noise contamination as well as the proximity and frequency of passing vehicle and foot traffic or other sources of transient noise contamination. Resonant frequencies ranged from 0.56 to 4.11 Hz, with associated uncertainty estimates ranging from 0.01 to 0.33 Hz. The analysis window for resonant frequencies was limited from 0.1-30 Hz. The HVSR measurements were evaluated using the SESAME reliability criteria; 38 measurements passed the criteria and 5 did not pass. The dataset includes the full site name, shorthand survey identifier, latitude and longitude, resonant frequency, uncertainty associated with the resonant frequency, collection duration, SESAME evaluation result, and date of acquisition for each passive seismic measurement. Resonant frequencies were not converted to an estimated depth to bedrock due to insufficient control points, 3 in total, within the study area.
