USGS scientists measuring temperature in a deep borehole in the Long Valley Caldera

By California Volcano Observatory June 2005 (approx.)

A drill rig mounted on a box truck suspends a cable over a square hole in the ground lined with wooden slats. One scientist in a green shirt and ball cap is halfway in the hole, while another in a safety helmet and gloves uses a long-handled tool to make an adjustment to equipment on the ground. In the background, rocky peaks dotted with snow rise above sagebrush-covered hills.

Detailed Description

USGS scientists measuring temperature in a deep borehole in Long Valley Caldera with the Sierra Nevada mountains in the background. Temperatures measurements were made with the USGS heat flow logging truck using a precise temperature sensor suspended on a cable. Measurements were obtained every foot (0.3048 meters) while lowering the cable at a constant rate. At the time of the measurement in June 2005, maximum temperature measured in this 1158-meter-deep borehole (number 13-26) on the southeast part of the resurgent dome was 135.3°C (275.5°F). Photo by Chris Farrar, U.S. Geological Survey.

Sources/Usage

Public Domain.