Self-potential and electric resistivity tomography data pertaining to groundwater flow for thermal springs, Hot Springs National Park, Arkansas, February 2023–January 2024

This data release contains self-potential (SP) map data, two-dimensional electrical resistivity tomography (ERT) data, and time-lapse SP-monitoring data measured within the thermal springs discharge area of Hot Springs National Park in Hot Springs, Arkansas, in addition to the geospatial coordinates of each geophysical measurement and photographs of the reconnaissance and monitoring-survey layouts. Hot Springs National Park features 47 artesian thermal springs that discharge along the trace of a thrust fault at the base of Hot Springs Mountain. To better understand temporal aspects of thermal springs discharge at Hot Springs National Park, the U.S. Geological Survey, in collaboration with the U.S. National Park Service, completed geophysical reconnaissance and monitoring surveys in the thermal-springs discharge area of the park where several thermal springs discharge from a subsurface bedrock aquifer into overburden fill sediments. Geophysical reconnaissance surveying comprised of SP mapping and ERT data collection occurred between February 20–23, 2023, prior to initializing the SP monitoring data collection on February 24, 2023. Geophysical reconnaissance was performed to (1) delineate electrical anomalies on the surface that were attributed to subsurface thermal springs discharge, (2) map the subsurface distribution of electrical resistivity within the thermal springs discharge area beneath two linear ERT survey lines, and (3) position a linear array of 40 copper-sulfate electrodes that were used to monitor the variations of electrical anomalies through time at 40 different locations on the land surface within the thermal springs discharge area. Each electrode in the linear SP monitoring array measured a voltage-difference relative to a common reference electrode every 60 seconds between 11:17 AM Central Standard Time (CST) on February 24, 2023 and 15:22 pm CST on January 8, 2024.