In July 2016, July 2019, and March 2020, 318 seismic recordings were acquired at locations within Shenandoah National Park, Virginia, using MOHO Tromino Model TEP-3C three-component seismometers to assess depth to bedrock using the HVSR method. This method requires a measurement of estimate of shear wave velocity, which depends on the regolith sediment composition and density, for the conversion of measured resonance frequency to a depth to bedrock. Shear wave velocities were calculated for sediment in Shenandoah NP at locations where regolith thickness is known (e.g. at documented boreholes). The locations in this study were generally selected to characterize the depths to bedrock adjacent to streams monitored for coupled temperature and flow dynamics related to several ongoing USGS projects.

This submission provides reports on the results of seismic data analyses, statistical data sets of rock properties under the DVGWF, GIS data for new maps of EGS favorability, and a link to raw seismogram data archived by the IRIS-DMS.

This submission provides reports on the results of seismic data analyses, statistical data sets of rock properties under the DVGWF, GIS data for new maps of EGS favorability, and a link to raw seismogram data archived by the IRIS-DMS.

A combination of long-term daily temperature records and depth to bedrock measurements were used to parametrize one-dimensional models of shallow aquifer vertical heat transport in Shenandoah National Park, VA, USA. Depth to bedrock can directly influence shallow aquifer flow and thermal sensitivity, but is typically ill-defined along the stream corridor in steep mountain catchments. We employed rapid, cost-effective passive seismic measurements to evaluate the variable thickness of the shallow colluvial and alluvial aquifer sediments along a headwater stream supporting coldwater-dependent brook trout (Salvelinus fontinalis) in Shenandoah National Park. The methods are fully documented in the associated journal article, Briggs, M.A., J.W. Lane, C.D. Snyder, E.A. White, Z.C. Johnson, D.L. Nelms, and N.P. Hitt, 2017, Shallow mountain bedrock limits seepage-based headwater climate refugia, Limnologica, https://dx.doi.org/10.1016/j.limno.2017.02.005. This Data Release includes seismic data collected as part of the study.

Included here are seismic data recorded at the San Emidio Geothermal field in Nevada. This passive seismic data were collected as part of the DOE-funded Subsurface Technology and Engineering R&D (SubTER) project to advance imaging and characterization of geothermal permeability. In December 2016, 1301 vertical-component seismic instruments were deployed at the San Emidio Geothermal field in Nevada. Data collection spanned a 160 hour timeframe, beginning on December 5th and ending on December 11th. Data are stored as individual files in one-minute increments in SEGD and MSEED formats and are downloadable as a zipped directory or available in a cloud-accessible format. Comprehensive metadata and project summaries are included in GDR submission 1386 (linked below as "2016 Seismic Survey Metadata at San Emidio").

Included here are seismic data recorded at the San Emidio Geothermal field in Nevada. This passive seismic data were collected as part of the DOE-funded Subsurface Technology and Engineering R&D (SubTER) project to advance imaging and characterization of geothermal permeability. In December 2016, 1301 vertical-component seismic instruments were deployed at the San Emidio Geothermal field in Nevada. Data collection spanned a 160 hour timeframe, beginning on December 5th and ending on December 11th. Data are stored as individual files in one-minute increments in SEGD and MSEED formats and are downloadable as a zipped directory or available in a cloud-accessible format. Comprehensive metadata and project summaries are included in GDR submission 1386 (linked below as "2016 Seismic Survey Metadata at San Emidio").

This data is in sac format and includes recordings of two active source events from 238 three-component nodal seismometers deployed at Bradys Hot Springs geothermal field as part of the PoroTomo project. The source was a viberoseis truck operating in P-wave vibrational mode and generating a swept-frequency signal. The files are 33 seconds long starting 4 seconds before each sweep was initiated. There is some overlap in the file times.

Lake Mead is a large interstate reservoir located in the Mojave Desert of southeastern Nevada and northwestern Arizona. It was impounded in 1935 by the construction of Hoover Dam and is one of a series of multi-purpose reservoirs on the Colorado River. The lake extends 183 km from the mouth of the Grand Canyon to Black Canyon, the site of Hoover Dam, and provides water for residential, commercial, industrial, recreational, and other non-agricultural users in communities across the southwestern United States. Extensive research has been conducted on Lake Mead, but a majority of the studies have involved determining levels of anthropogenic contaminants such as synthetic organic compounds, heavy metals and dissolved ions, furans/dioxins, and nutrient loading in lake water, sediment, and biota (Preissler, et al., 1998; Bevans et al, 1996; Bevans et al., 1998; Covay and Leiker, 1998; LaBounty and Horn, 1997; Paulson, 1981). By contrast, little work has focused on the sediments in the lake and the processes of deposition (Gould, 1951). To address these questions, sidescan-sonar imagery and high-resolution seismic-reflection profiles were collected throughout Lake Mead by the USGS in cooperation with researchers from University of Nevada Las Vegas (UNLV). These data allow a detailed mapping of the surficial geology and the distribution and thickness of sediment that has accumulated in the lake since the completion of Hoover Dam. Results indicate that the accumulation of post-impoundment sediment is primarily restricted to former river and stream beds that are now submerged below the lake while the margins of the lake appear to be devoid of post-impoundment sediment. The sediment cover along the original Colorado River bed is continuous and is typically greater than 10 m thick through much of its length. Sediment thickness in some areas exceeds 35 m while the smaller tributary valleys typically are filled with less than 4 m of sediment. Away from the river beds that are now covered with post-impoundment sediment, pre-impoundment alluvial deposits and rock outcrops are still exposed on the lake floor.

Transient electromagnetic (TEM) soundings were made in the San Luis Valley, Colorado, to map the location of a blue clay unit as well as to investigate the presence of suspected faults. A total of 147 soundings were made near and in Great Sand Dunes National Park and Preserve, an additional 6 soundings were made near Hansen Bluff on the eastern edge of the Alamosa National Wildlife Refuge. The blue clay is a significant hydrologic feature in the area that separates an unconfined surface aquifer from a deeper confined aquifer. Knowledge of its location is important to regional hydrological models. Previous analysis of well logs has shown that the blue clay has a resistivity of 10 ohm-meters or less, which is in contrast to the higher resistivity of sand, gravel, and other clay units found in the area, making it a very good target for TEM soundings. The top of the blue clay was found to have considerable relief suggesting the possibility of deformation of the clay during or after deposition. Because of rift activity deformation is to be expected. Of the TEM profiles made across faults identified by aeromagnetic data, some showed resistivity variations and (or) subsurface elevation relief of resistivity units suggestive of faulting. Such patterns were not associated with all suspected faults. The Hansen Bluff profile showed variations in resistivity and depth to conductor that coincide with a scarp between the highlands to the east and the floodplain of the Rio Grande River to the west.