Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (less than 1 m) and deeper (greater than 1 m) impacts of fire on permafrost along 14 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Electrical resistivity tomography (ERT) data collected along the 14 transect were used to map the spatial distribution of permafrost across burned-unburned boundaries.

Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (less than 1 m) and deeper (greater than 1 m) impacts of fire on permafrost along 14 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Electrical resistivity tomography (ERT) data collected along the 14 transect were used to map the spatial distribution of permafrost across burned-unburned boundaries.

In June 2017, U.S. Geological Survey (USGS) collected geophysical measurements to help map variations in electrical properties to infer shallow flowpaths and storage zones influenced by residual spilled unconventional oil and gas (UOG). Two survey profiles were collected, each including dipole-dipole and Wenner-Schlumberger configurations. For each survey a total of 56 electrodes spaced 1.0 meter (m) apart were used. During the ERT measurement, current is injected through two current electrodes and voltage is measured sequentially across multiple pairs of potential electrodes; the known current and the measured voltages are used to determine the apparent resistivity of the subsurface. Inverse modeling of ERT survey results provide profiles of resistivity that can be interpreted for subsurface layers. This data release provides the raw ERT data and output from inversion.

Electrical resistivity tomography (ERT) surveys were done northwest of the Air Force Research Laboratory (AFRL) at Edwards Air Force Base. ERT surveys were done at four locations in May through June of 2018 to refine the understanding of the bedrock-alluvial aquifer transition zone downgradient from the AFRL. The ERT technique injects direct-current electricity with known voltage and current into the earth using a series of electrodes and measures the resulting resistivity. This technique is generally limited to investigations of aquifer properties less than 100 meters below land surface. Data from other geophysical techniques co-located with the ERT data, including time-domain electromagnetics and horizontal-to-vertical spectral ratio passive seismic, are made available in other child pages within this data release: https://doi.org/10.5066/P9ZGZTA4. This page contains the ERT data, spatial information for the ERT transects, and preliminary processed ERT data.

Surface electrical resistivity tomography (ERT), magnetic, and gravity surveys were conducted in July 2017 in the greater East River Watershed near Crested Butte Colorado with a focused effort in Redwell Basin as part of a broader study of the role of bedrock groundwater in the hydrogeology of mineralized mountain watersheds. Five electrical resistivity tomography profiles were acquired within Redwell Basin and Brush Creek to map geologic structure at depths up to 40 meters, depending on the subsurface resistivity, using the Advanced Geosciences, Inc. SuperSting R8 resistivity meter. This data release includes the raw and processed resistivity data as well as inverted resistivity models. All are provided as digital data, and data fields for each file type are defined in the respective data dictionary.

Surface electrical resistivity tomography (ERT), magnetics, and gravity data were acquired in July 2017 in the greater East River Watershed near Crested Butte Colorado with a focused effort in Redwell Basin. Five ERT profiles were acquired within Redwell Basin and Brush Creek to map geologic structure at depths up to 40 meters, depending on the subsurface resistivity, using the Advanced Geosciences, Inc. SuperSting R8 resistivity meter. Approximately ten kilometers of total field magnetics data were acquired with a Geometrics G-858 cesium vapor magnetometer that detects changes in deep (tens of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations. Ten gravity stations were acquired with a LaCoste and Romberg G-model relative gravimeter to map density variations. This data release includes raw data for all methods as well as processed and/or inverted resistivity or water content models. Digital data from all methods are provided, and data fields are defined in respective data dictionaries.

The Cahuilla Valley and Terwilliger Valley groundwater basins, 9-006 and 7-026 respectively (California Department of Water Resources 2016) located approximately 25 miles southwest of Palm Springs, are the sole-source for groundwater supply for the rural disadvantaged community and two Native American Tribes, the Ramona Band of Cahuilla and the Cahuilla. The characteristics and sustainable yield of the Cahuilla Valley and Terwilliger Valley groundwater basins are not well understood and are threatened by increasing water use and potential changes in water sustainability related to climate change. Previous USGS studies of the Cahuilla-Terwilliger Valley groundwater basins defined the thicknesses and characteristics of the alluvial sediments that constitute the main water-bearing unit of the aquifer system and identified where wells completed in the underlying fractured bedrock are located (Moyle, 1976; Landon and others, 2015; Woolfenden and Bright, 1988). However, although the fractured bedrock is an important part of the aquifer system for domestic and some irrigation supply, the thickness and hydraulic characteristics of the fractured bedrock are not well understood (Landon and others, 2015; Moyle 1976). Existing gravity data identified a possible conduit for groundwater flow beneath Cahuilla Creek in the Cahuilla and Durasno Valleys (Landon and others, 2015). Electrical resistivity tomography (ERT) data was collected in August 2018 to evaluate the cross-sectional depth to bedrock underlying a narrow section of Durasno Valley, and to help select locations for groundwater monitoring wells. Data from two transects were collected perpendicular to Cahuilla Creek, and offset by approximately 600 meters (m).

The Cahuilla Valley and Terwilliger Valley groundwater basins, 9-006 and 7-026 respectively (California Department of Water Resources 2016) located approximately 25 miles southwest of Palm Springs, are the sole-source for groundwater supply for the rural disadvantaged community and two Native American Tribes, the Ramona Band of Cahuilla and the Cahuilla. The characteristics and sustainable yield of the Cahuilla Valley and Terwilliger Valley groundwater basins are not well understood and are threatened by increasing water use and potential changes in water sustainability related to climate change. Previous USGS studies of the Cahuilla-Terwilliger Valley groundwater basins defined the thicknesses and characteristics of the alluvial sediments that constitute the main water-bearing unit of the aquifer system and identified where wells completed in the underlying fractured bedrock are located (Moyle, 1976; Landon and others, 2015; Woolfenden and Bright, 1988). However, although the fractured bedrock is an important part of the aquifer system for domestic and some irrigation supply, the thickness and hydraulic characteristics of the fractured bedrock are not well understood (Landon and others, 2015; Moyle 1976). Existing gravity data identified a possible conduit for groundwater flow beneath Cahuilla Creek in the Cahuilla and Durasno Valleys (Landon and others, 2015). Electrical resistivity tomography (ERT) data was collected in August 2018 to evaluate the cross-sectional depth to bedrock underlying a narrow section of Durasno Valley, and to help select locations for groundwater monitoring wells. Data from two transects were collected perpendicular to Cahuilla Creek, and offset by approximately 600 meters (m).