July 29, 2026 — Sulfur Cone gas monitoring maintenance, Mauna Loa

On July 29, 2026, USGS Hawaiian Volcano Observatory gas scientists flew via helicopter to the Sulfur Cone Multi-Gas instrumentation site on Mauna Loa's Southwest Rift Zone, which is at an elevation of 3,430 meters (11,240 feet) above sea level. Their mission was to perform routine maintenance of the monitoring site and to swap in a newly calibrated Multi-Gas instrument. In this photo, a gas scientist works to install the new Multi-Gas instrument which is used to monitor volcanic gas emissions emanating from the still steaming fissure formed during the 1950 Mauna Loa eruption in the background. USGS Photo by M. Cappos.