Sand miner trapped by large lahar on Mount Semeru, Indonesia
A large lahar triggered by heavy rains on Mount Semeru trapped a man in the Regoyo River in East Java, on Sunday, December 21, 2025.

A large lahar triggered by heavy rains on Mount Semeru trapped a man in the Regoyo River in East Java, on Sunday, December 21, 2025.

New activity/unrest was reported for 5 volcanoes from December 10 to 16, 2025. During the same period, ongoing activity was reported for 17 volcanoes.

New activity/unrest was reported for 7 volcanoes from December 3 to 9, 2025. During the same period, ongoing activity was reported for 21 volcanoes.

A glacial outburst flood in Iceland’s Skaftá River, first detected on December 8, 2025, has been confirmed to originate from the Vestari-Skaftár caldera beneath Vatnajökull ice cap. Flow at the Sveinstind station has decreased to just over 120 m³/s, down from 200 m³/s earlier in the week. Conductivity remains high and hydrogen sulfide continues to be detected along the river, but no impacts on major roads have been reported.

A powerful lava fountain from Kīlauea’s Halemaʻumaʻu crater, Hawaiʻi, destroyed the USGS Hawaiian Volcano Observatory’s V3 streaming camera at around 10:00 HST (20:00 UTC) on December 6, 2025. The camera was recording live when an inclined fountain from the south vent buried it in hot pumice and tephra during Episode 38 of the ongoing summit eruption.

Kīlauea’s Halemaʻumaʻu crater, Hawaiʻi, began erupting at 08:45 HST (18:45 UTC) on December 6, 2025, when fountains emerged from the north vent, marking the start of Episode 38 of the ongoing summit eruption. Within minutes, a south vent opened, and by 09:15 HST a rare triple-vent lava fountain was active, producing jets up to 370 m (1 200 ft) high and a 6 km (20 000 feet) plume above the summit. The eruption lasted 12.1 hours, covered more than half of Halemaʻumaʻu crater with new lava, destroyed the USGS V3 streaming camera, and ended abruptly at 20:52 HST on the same day (06:52 UTC on December 7).

Low-level eruptive activity resumed at Ambae volcano (Manaro Voui) in Vanuatu, with intermittent ash emissions observed since December 1, 2025. Satellite imagery from Himawari-9 confirmed continuous low-level ash and gas plumes reaching up to 1.8 km (6 000 feet) above sea level, drifting northwest. The Wellington Volcanic Ash Advisory Centre (VAAC) issued its latest advisory on December 4, describing the eruption as continuous but confined within the volcano’s summit area.

New activity/unrest was reported for 9 volcanoes from November 26 to December 2, 2025. During the same period, ongoing activity was reported for 20 volcanoes.

Volcanic activity at Puracé, Colombia, intensified on November 30, 2025, prompting authorities to raise the alert level to Orange for the Los Coconucos volcanic chain in Cauca Department on December 1. Since then, continuous tremor, long-period seismicity, and sustained gas-and-ash emissions have been recorded, with columns exceeding 700 m (2 300 feet) above the summit (4 650 m / 15 260 a.s.l.) and occasional ashfall reported in nearby communities.

A powerful explosive eruption took place at Bezymianny volcano in Kamchatka, Russia, on November 26, 2025, with ash reaching 11.4 km (37 400 feet) a.s.l., as of 04:00 UTC. The Aviation Color Code was raised to Red due to ongoing explosions that could affect regional and international flights.