August 22, 2025 — Episode 31 inclined fountains in Halema‘uma‘u crater at the summit of Kīlauea

During Kīlauea summit eruption episode 31 on August 22, inclined lava fountains extended 300 meters (1000 feet) laterally from the north vent, going eastward towards the center of Halemaʻumaʻu crater. Inclined lava fountains have been observed before on Kīlauea, in both the Kīlauea Iki (1959) and Maunaulu eruptions (1969) that featured similar episodes of lava fountaining. In both previous cases, the inclined fountains were caused by temporary obstructions within the eruptive vents, usually collapse of part of the vent or surrounding cone. Today’s incline could be caused by construction of an inner cone during the precursory activity before the start of the episode. It’s similar to if you’ve ever put your thumb over a garden hose, causing the water to spray out of the hose at an angle. USGS photo by M. Zoeller.