Ash cloud 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 21:10 UTC on October 30, 2025. The advisory was issued by Darwin VAAC at 21:30 UTC on the same day.

The ash cloud was reported between the surface and flight level 140 (approximately 4 300 m or 14 100 feet). The movement of the ash was towards the southwest at 9 km/h (6 mph). Ash was not identifiable on satellite imagery due to meteorological cloud cover, but multiple ground reports and webcam imagery indicated intermittent discrete eruptions were ongoing. The current Aviation Color Code is Orange.

According to the Smithsonian / USGS Weekly Volcanic Activity Report for the week ending September 30, 2025, daily eruptive events at Semeru were recorded, with ash plumes rising 400–900 m above the summit and drifting in multiple directions. The Alert Level remained at 2, and the public was advised to stay at least 3 km from the summit in all directions, and 8 km to the southeast, due to lahar and pyroclastic flow hazards.

Semeru is an active stratovolcano located in East Java, Indonesia, and is the highest volcano on the island. Hazards from Semeru include frequent ashfall, pyroclastic flows, lava flows, and lahars. Nearby settlements such as the town of Lumajang and villages on the southern and eastern flanks are most at risk during eruptions, especially within a 10 km (6.2 miles) radius of the summit.