Volcanic ash from Semeru volcano observed at 4 600 m (15 000 feet) a.s.l., Indonesia

Volcanic ash from Semeru volcano in Indonesia was observed at 4 600 m (15 000 feet) above sea level at 02:50 UTC on November 12, 2025. The advisory was issued by the Darwin VAAC at 03:15 UTC.

Ash was forecast in the altitude band from the surface up to flight level 150 (approximately 4 600 m or 15 000 feet). Movement of the ash cloud was toward the southeast at approximately 9 km/h (5 mph). Due to meteorological cloud cover, volcanic ash was not identifiable on satellite imagery, and reported heights and movements were based on recent eruptive behaviour and model guidance. The current Aviation Color Code is Orange.

According to the Smithsonian / USGS Weekly Volcanic Activity Report, activity at Semeru continued during the previous week, with daily eruptive events recorded by the seismic network. Daily white-and-gray or gray ash plumes rose 400–900 m above the summit and drifted in multiple directions. The Alert Level was at 2. The public was advised to stay at least 3 km away from the summit and 8 km southeast, with additional warnings for nearby drainages due to lahar and pyroclastic flow hazards.

Semeru is a stratovolcano located in East Java, Indonesia. It is one of Indonesia’s most active volcanoes, posing hazards including ashfall, lava flows, pyroclastic flows, and lahars. The nearest major settlement is the city of Lumajang, located about 30 km (19 miles) to the southeast, with numerous villages situated within 10 km (6 miles) of the volcano’s slopes.