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 09:20 UTC on November 5, 2025. The advisory was issued by the Darwin VAAC at 09:40 UTC.

Ash was reported between the surface and flight level 150 (approximately 4 600 m or 15 000 feet). Movement of the ash cloud was towards the northeast at a speed of 18 km/h (11 mph). The volcanic ash cloud could not be identified on satellite imagery owing to meteorological cloud cover. Recent ground reports indicate intermittent discrete eruptions are ongoing. Ash height and movement were based on ground reports and model guidance. The current Aviation Color Code is Orange.

According to the Smithsonian / USGS Weekly Volcanic Activity Report, activity continued at Semeru during the week of September 24–30, 2025, with daily eruptive events recorded by the seismic network. Daily 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 Alert Level remained at 2. The public was advised to stay at least 3 km (1.9 miles) from the summit in all directions and observe further distance restrictions in specified hazard zones.

Semeru is a stratovolcano located in East Java, Indonesia. It is the highest volcano on the island and is known for frequent explosive eruptions, producing ash plumes, lava flows, and pyroclastic flows. Hazards from Semeru include ashfall, lava flows, pyroclastic density currents, and lahars. The nearest city, Lumajang, is located about 25 km (16 miles) southeast, with several villages in closer proximity and at risk from volcanic hazards.