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Passive seismic depth to bedrock data collected along headwater stream corridors in the Neversink River watershed, NY, USA

December 14, 2020

The Neversink River watershed (above the Neversink Reservoir) has been a focus of U.S. Geological Survey (USGS) research regarding stream geochemistry, acidification, and ecology dynamics for decades. In 2019, the Water Mission Area Next Generation Water Observing Systems Program augmented the existing stream gage network there, including instrumentation to specifically characterize various aspects of groundwater discharge to streams. An important control on the spatiotemporal dynamics of groundwater discharge can be stream valley corridor depth to bedrock, otherwise conceptualized as the thickness of unconsolidated sediments sediments over the contiguous bedrock interface. In June 2019, and November 2020, passive seismic recordings were acquired at locations directly along stream banks in the Neversink River watershed, using MOHO Tromino Model TEP-3C (MOHO, S.R.L.) three-component seismometers to assess depth to bedrock using the horizontal-to-vertical spectral-ratio (HVSR) method. Resonance frequencies were derived from the raw data using the GRILLA software (MOHO, S.R.L.) and converted to inferred depths to the bedrock contact. This method requires a value for seismic shear wave velocity, which depends on the unconsolidated sediment composition and density, for the conversion of HVSR measured resonance frequency to a depth to bedrock. Possible shear wave velocities were estimated for Neversink River watershed sediment based on previous research in the glacial terrain of the Northeast USA, providing a range of possible data interpretations as shown in the ?Processed_Data? folder of this data release. We expect to update the release in the future as additional HVSR data are collected.