Another lava-fountaining episode began in Kilauea’s Halemau’mau’u summit crater late evening at 10:57 p.m. HST local time on March 31 from the north vent. It is number 16 of the ongoing eruption began.
USGS reports that „Episode 16 was preceded by weak spattering in the north vent that began at approximately 5:20 p.m. HST on March 31, 2025. Since 6:00 p.m. HST, spattering became continuous and increased to low fountaining (15-30 feet or 5-10 meters high). Lava level gradually rose in the vent and is now overflowing out of the north vent cone onto the floor of Halemaʻumaʻu. Each of the prior 15 episodes ultimately involved significant lava fountaining, with the fountains of episode 15 exceeding 1,000 feet (305 meters) in height. High lava fountains are likely to follow the current dome fountaining and lava flows within 24 hours or less.
„Inflationary tilt on the UWD tiltmeter reached around 8 microradians since the end of the last episode, recovering about 90% of the tilt lost from episode 15. UWD tilt has flattened, but has not started deflating, at this time. Seismic tremor initially began increasing around noon HST on March 31, 2025, followed by a sharper increase around 4:30 p.m. HST the same afternoon. Tremor continues to steadily increase. Infrasound signals also strengthened beginning just before 6 p.m. HST when spattering became continuous and visible in north vent.
„Emissions of SO2 gas are elevated, and during recent episodes have reached 50,000 tonnes per day or more, and similar amounts of gas are expected to accompany any high fountaining activity that may occur during episode 16. Currently, winds at the summit are forecast to be weak, which may allow the plume of gas to spread around the summit region of Kīlauea. In addition, visitors to Hawaiʻi Volcanoes National Park and residents of adjacent areas may be exposed to Peleʻs hair and other small fragments of volcanic glass and tephra being carried in the plume, as they were during episode 15.
„Each episode of Halemaʻumaʻu lava fountaining since December 23, 2024, has continued for 13 hours to 8 days, and episodes have been separated by pauses in eruptive activity lasting less than 24 hours to 12 days.“