Volcanic ash from Semeru observed at 4 300 m (14 100 feet) a.s.l., Indonesia

Volcanic ash from Semeru in Indonesia was observed at 4 300 m (14 100 feet) above sea level at 09:40 UTC on October 13, 2025. The advisory was issued by the Darwin VAAC at 10:00 UTC on the same day.

According to the advisory, the ash cloud was reported between the surface and 4 300 m (14 100 feet). The movement of the ash was toward the west at an estimated speed of 37 km/h (23 mph). The ash cloud was not visible in recent satellite imagery due to meteorological clouds; ground reports and model guidance were used to determine ash height and movement. The current Aviation Color Code is Orange.

The Global Volcanism Program reports that during September 24–30, 2025, Semeru produced daily eruptive events with white-and-gray or gray ash plumes rising 400–900 m above the summit and drifting in multiple directions. The Alert Level remained at 2, and the public was advised to stay at least 3 km away from the summit in all directions, and farther in some sectors due to hazard zones.

Semeru is an active stratovolcano located in East Java, Indonesia, and is the highest volcano on the island. The main hazards include ashfall, pyroclastic flows, lava flows, and lahars. Populations at risk include local towns such as Lumajang, located roughly 30 km (19 miles) from the crater, and other settlements in the surrounding region.