Horizontal-to-vertical spectral ratio soundings and depth-to-bedrock data for valley-fill aquifers in the Oneonta area, Otsego and Delaware Counties, New York, 2016 - 2018

From 2016 through 2018, the U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, collected horizontal-to-vertical seismic soundings at 71 locations in the major valleys in the Oneonta area, Otsego and Delaware Counties, New York to help determine thickness of the unconsolidated deposits and the bedrock surface elevation. The HVSR technique, commonly referred to as the passive-seismic method, is used to estimate the thickness of unconsolidated sediments and the depth to bedrock (Lane and others, 2008; Fairchild and others, 2013). The passive-seismic method uses a single, broad-band three-component (two horizontal and one vertical) seismometer to record ambient seismic noise. In areas that have a strong acoustic contrast between the bedrock and overlying sediments, the seismic noise induces resonance at frequencies that range from about 0.3 to 40 Hz. The ratio of the average horizontal-to-vertical spectrums produces a spectral-ratio curve with peaks at fundamental and higher-order resonance frequencies. The spectral ratio curve (the ratio of the averaged horizontal-to-vertical component spectrums) is used to determine the fundamental resonance frequency that can be used along with an average shear-wave velocity or a power-law regression equation to estimate sediment thickness and depth to bedrock (Lane and others, 2008; Brown and others, 2013; Fairchild and others, 2013; Chandler and others, 2014; and Johnson and Lane, 2016). The HVSR data presented in this data release were collected at each site for 30 minutes using a Tromino Model TEP-3C three-component seismometer. The data were processed with Grilla 2012 version. 6.2 software to: 1) remove anthropogenic noise, 2) convert the time-domain data to frequency domain, 3) compute and plot the spectral ratio curve, and 4) determine the resonance frequency. This data release presents the resonance frequency peaks identified from the HVSR measurements. Raw and processed HVSR data for each HVSR measurement are presented in the attached files. The HVSR data-collection sites are designated by a county sequential numbering system (OGHVSR79, DHVSR1, etc. where "OG" indicates Otsego County and "D" indicates Delaware County).