Volcanic ash from Semeru volcano observed at 4 300 m (14 000 feet) a.s.l., Indonesia

Volcanic ash from Semeru volcano in Indonesia was observed at 4 300 m (14 000 feet) above sea level at 21:40 UTC on October 13, 2025. The advisory was issued by the Darwin VAAC at 22:00 UTC on the same day.

According to the advisory, ground reports indicated intermittent discrete ash eruptions continuing from Semeru. The ash cloud was observed up to 4 300 m (14 000 feet) and was moving west at approximately 28 km/h (17 mph). Ash was not identifiable on recent satellite imagery due to meteorological cloud cover; observations are based on ground reports and model guidance. The current Aviation Color Code is Orange.

The Weekly Volcanic Activity Report from the Smithsonian’s Global Volcanism Program noted that daily eruptive events at Semeru continued during late September 2025, with white-and-gray or gray ash plumes rising 400–900 m (1 300–2 950 feet) above the summit and drifting in multiple directions. The Alert Level remained at 2, and the public was advised to maintain safety distances of 3 km (1.9 miles) from the summit in all directions and 8 km (5 miles) to the southeast.

Semeru is a stratovolcano located in East Java, Indonesia. It is known for frequent explosive eruptions and pyroclastic flows. Hazards associated with this volcano include ashfall, pyroclastic flows, lahars, and lava avalanches. The nearby population includes several settlements and the city of Lumajang, approximately 30 km (19 miles) to the southeast, which could be affected during significant eruptive activity.