Alaska permafrost characterization: Electrical Resistivity Tomography Data & Models from 2019

Electrical resistivity tomography (ERT) measurements were collected by the U.S. Geological Survey (USGS) at two sites in Interior Alaska in September 2019 for the purposes of imaging permafrost structure and quantifying variations in subsurface moisture content in relation to thaw features. First, ERT data were collected at Big Trail Lake, a thermokarst lake outside of Fairbanks, Alaska, to quantify permafrost characteristics beneath the lake and across its shorelines. Three 222 m ERT survey lines were collected perpendicular to the North, East, and South shorelines, and two 110 m lines were collected parallel to the southeast and northeast shorelines. Models of electrical resistivity produced from these data revealed the distribution of frozen and thawed soil to depths of 10-40 m below the surface. Second, an ERT survey was conducted at Bonanza Creek LTER (Long Term Ecological Research), approximately 30 km southwest of Fairbanks, Alaska. This survey was a repeat of a previous ERT survey done in the same exact location in late August 2016, those data and models can be found here. The new survey line was 125 m in length and spanned the transition between burned and unburned forest. Models of electrical resistivity for this site imaged the structure of frozen and thawed soils to depths of 10-15 m. At both sites, manual permafrost-probe measurements of thaw depths were collected at set intervals along each ERT transect and used for comparison to the resistivity models.