Ash plume from Semeru volcano reaches 4 300 m (14 100 feet) a.s.l., Indonesia

Volcanic ash from Semeru volcano in Indonesia was observed at 4 300 m (14 100 feet) above sea level at 09:20 UTC on October 23, 2025. The advisory was issued by the Darwin VAAC at 09:40 UTC.

Ash was reported from the surface up to flight level 140 (approximately 4 300 m or 14 100 feet). The ash cloud was moving southwest at around 9 km/h (5 mph). The Darwin VAAC noted that ash could not be identified in current satellite imagery due to meteorological cloud cover, but ground reports confirmed intermittent discrete eruptions were ongoing. The current Aviation Color Code is Orange.

According to the Smithsonian/USGS Weekly Volcanic Activity Report, activity continued at Semeru during September 24–30, 2025, with daily eruptive events. Ash plumes during that week rose 400–900 m above the summit and drifted in several directions. The Alert Level remained at 2, and the public was advised to maintain a safe distance from the volcano and downstream hazards.

Semeru is a stratovolcano and the highest volcano on Java, Indonesia. It regularly produces ash plumes, pyroclastic flows, and lava avalanches. Hazards include ashfall, lava and pyroclastic flows, and lahars impacting river valleys. Nearby communities such as Pronojiwo and Lumajang, located within 20 km (12 miles), may be at risk from volcanic hazards during increased activity.