Water level, temperature and chemistry in a deep well on the summit of Kilauea Volcano, Hawaii

Kilauea, on the Island of Hawaii is one of the world's most active volcanoes and it hosts one of the densest volcano monitoring networks. A deep well on the southwest rim of Kilauea's caldera, often referred to informally as the "NSF Well" or the "Keller Well" was drilled in 1973 to a depth of 1,262 meters from an elevation of 1,103 meters. The ultimate goal of the drilling project was to "test predictions made from surface-based geophysical surveys and seek evidence of a hydrothermal system over a known magma body" (Zablocki et al., 1974; Keller et al., 1979). Following drilling the open hole filled up with drilling mud and in October 1998 the hole was cleared of the mud using a large pump to a depth of about 2,200 feet (~670 meters). Cleaning of the well renewed access to the hydrothermal system very close to the loci of magmatic and fumarolic activity. Following drilling in 1973 and then again in 1999 downhole water level and temperature measurements were made (Keller et al., 1979; Hurwitz et al. 2002). In July 2000, a package of geodetic and seismic instruments was installed in the unsaturated part of the well at a depth of 1,200 feet (366 meters) below the ground surface. A 2-inch (OD) PVC pipe between the instruments and the surface allowed for water level and temperature measurements and waster sampling to continue. Between February and June 2001, water level in the well was measured with a gas line and two pressure transducers (Hurwitz and Johnston, 2003). Further attempts for continuous instrumental water level measurements by the USGS have failed. The well was sampled several times between October 1998 and March 2002 for water chemistry and isotope analyses (Hurwitz et al., 2003). It was revealed that the chemical and isotopic compositions of the post-cleaning samples differ remarkably from water samples collected before cleaning. Between March 2002 and May 2011, U.S. Geological Survey scientists have made periodic water level measurements and collected water samples for limited chemical and isotopic analysis. The goal of this effort was to track changes in water level and the concentrations of magmatic volatiles (chlorine, sulfur and carbon dioxide) dissolved in groundwater in relation to volcanic activity in Kilauea. The data presented here includes water level measurements, anion (sulfate, chloride, and fluoride) concentrations, and oxygen and deuterium isotopes of sampled waters, and two temperature profiles that were measured in 2008 and 2019.