Temperature Data From Wells in Long Valley Caldera, California, 2018-present

This data release consists of well temperature logs from Long Valley Caldera, California, which have been measured to characterize the spatial and temporal variations of the subsurface heat flow. Two methods were used to measure temperatures. The first method, a portable hand cranked reel with a platinum resistance thermometer (PRT), with an accuracy and precision of 0.1 degrees Celsius, was used to measure the water temperatures in wells CH-1, CH-5, CH-6, and CH-10b. Measurements were performed by lowering the cable down the well while an associated data logger recorded temperature readings at 5 second intervals. For each well log, the PRT was lowered, pausing at predetermined depths for 1-2 minutes to allow the temperature to reach a stable value. After stability was achieved, recorded data was averaged to yield a single value for each depth. The files from these wells contain two columns with headers Depth_ft and Temp_degC, and the filenames are written in "CH-XX_YYYY" format.

Continuous temperature measurements were made in well MW-4. Four PRTs were installed in the well at depths of 50 ft, 150 ft, 210 ft, and 300 ft and connected to a data logger programmed to record the temperature every thirty seconds. The data was then retrieved and processed to remove outlier values. The file contains six columns: DateTime, RECORD, and four columns for the temperature at different depths, labeled with Temp_XXft_degC. The file is labeled with the well name and year of collection.

Citations:

Farrar, C., DeAngelo, J., Clor, L., Murphy, F., Williams, C., Grubb, F., and Hurwitz, S., 2010, Temperature data from wells in Long Valley Caldera, California (ver. 3.0, November 2016): U.S. Geological Survey Data Series 523, https://pubs.usgs.gov/ds/523/.