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

Volcanic ash from Semeru volcano in Indonesia was observed at 4 300 m (14 100 feet) above sea level at 21:10 UTC on October 27, 2025. The advisory was issued by the Darwin VAAC at 21:30 UTC.

According to the advisory, ash was reported to flight level 140 (approximately 4 300 m or 14 100 feet) with movement toward the southwest at about 9 km/h (6 mph). The ash cloud was not identifiable in satellite imagery due to meteorological clouds; ground reports indicated intermittent discrete eruptions were ongoing. Ash height and movement were determined based on ground observations and model guidance. The current Aviation Color Code is Orange.

According to the latest Smithsonian / USGS Weekly Volcanic Activity Report, daily eruptive events were recorded at Semeru during September 24-30, 2025. White-and-gray or gray ash plumes rose 400–900 m (1 300–2 950 feet) above the summit and drifted in multiple directions. The public was warned to remain outside hazard zones surrounding the volcano due to lahar, avalanche, and pyroclastic flow hazards.

Semeru is a stratovolcano located in East Java, Indonesia. Known hazards include ashfall, lava flows, pyroclastic flows, and lahars. Nearby populated areas at risk include the towns of Lumajang and Malang, as well as smaller villages within 20 km (12 miles) of the volcano’s summit.