May 21, 2025 — UAS close-up of south vent lava pond

During UAS (uncrewed aircraft systems) overflights on May 21, USGS Hawaiian Volcano Observatory geologists flew their aircraft directly above the south vent within Halemaʻumaʻu at the summit of Kīlauea. They observed gas pistoning cycles within the vent, as a lava pond gradually rose over the course of an hour before rapidly dropping over a few tens of seconds as gas was expelled. Here, the lava pond—estimated to measure about 5–10 meters (16–33 feet) wide—can be seen near the peak of its rise. These UAS flights were conducted with the permission of Hawaiʻi Volcanoes National Park, owing to the USGS Hawaiian Volcano Observatory's mission to monitor active volcanoes in Hawaii, assess their hazards, issue warnings, and advance scientific understanding to reduce the impacts of eruptions. Unauthorized launching, landing, or operating of a UAS from or on lands and waters administered by the National Park Service is prohibited under 36 CFR Closures & Public Use. USGS photo by M. Zoeller.