Volcanic ash from Semeru volcano 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 03:00 UTC on October 30, 2025. The advisory was issued by the Darwin VAAC at 03:30 UTC on October 30, 2025.

Ash from Semeru was reported up to flight level 140, which is approximately 4 300 m (14 100 feet) above sea level, moving west at about 19 km/h (12 mph). The source information came from CVGHM and Himawari-8 satellite, though the ash cloud was not identifiable in the latest satellite imagery due to meteorological clouds. Reports indicate intermittent discrete eruptions remain ongoing. The current Aviation Color Code is Orange.

According to the Smithsonian / USGS Weekly Volcanic Activity Report for September 24–30, 2025, Semeru exhibited ongoing eruptive activity. Daily white-and-gray or gray ash plumes rose 400–900 m (1 300–3 000 feet) above the summit and drifted in multiple directions. The public was advised to remain at least 3 km (1.9 miles) from the summit in all directions and 8 km (5 miles) from the summit to the southeast, with further restrictions along the Kobokan drainage.

Semeru is a stratovolcano located in East Java, Indonesia. It is known for its frequent explosive eruptions, producing hazards such as ashfall, pyroclastic flows, lava flows, and lahars. Settlements at risk include the city of Lumajang, as well as several smaller villages within 20 km (12 miles) of the volcano. The area southeast of Semeru is particularly vulnerable to lahars and pyroclastic flows.