Ash emissions from Semeru volcano reach 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 15:00 UTC on October 24, 2025. The advisory was issued by the Darwin VAAC at 15:30 UTC.

According to the VAAC advisory, the ash cloud extended from the surface up to flight level 140, corresponding to approximately 4 300 m (14 100 feet). The ash was moving southwest at approximately 19 km/h (12 mph), based on ground reports and consensus model guidance. Satellite imagery from Himawari-8 was inconclusive due to meteorological cloud cover, but intermittent discrete eruptions were reported from the ground. The current Aviation Color Code is Orange.

The Smithsonian / USGS Weekly Volcanic Activity Report for 24–30 September 2025 states that Semeru exhibited daily eruptive events, producing ash plumes rising 400–900 m above the summit and drifting in multiple directions. The Alert Level remained at Level 2, and the public was advised to remain at least 3 km from the summit, 8 km to the southeast, and avoid drainages threatened by lahar and pyroclastic flow hazards.

Semeru is a stratovolcano and Indonesia’s highest volcano, located in eastern Java. It is known for frequent explosive eruptions, which can produce ashfall, pyroclastic flows, and lahars. The city of Lumajang, located about 30 km (19 miles) to the southeast, and smaller villages on the flanks are potentially at risk from volcanic hazards including ashfall and pyroclastic flows.