Volcanic ash 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 09:40 UTC on October 22, 2025. The advisory was issued by the Darwin VAAC at 10:00 UTC on the same day.

According to the VAAC advisory, ash was reported from ground observations to have reached approximately 500 m (1 600 feet) above the 3 657 m (11 998 feet) summit, placing the ash cloud at up to 4 300 m (14 100 feet) above sea level. The Aviation Color Code is Orange. Volcanic ash was not identifiable in satellite imagery due to meteorological cloud cover. Ash movement was reported toward the west at a speed of 9 km/h (6 mph) based on ground reports and model guidance. No other cloud parameters or velocities were provided.

According to the latest Smithsonian / USGS Weekly Volcanic Activity Report, Semeru experienced daily eruptive activity during 24–30 September 2025. Daily white-and-gray or gray ash plumes rose 400–900 m (1 300–3 000 feet) above the summit and drifted in multiple directions. The Alert Level remained at 2, and the public was advised to remain at least 3 km (1.9 miles) from the summit in all directions, with extended exclusions southeast and along drainages.

Semeru is a stratovolcano located in East Java, Indonesia. It is the highest volcano on the island and is known for frequent explosive eruptions that produce ash plumes, lava flows, and pyroclastic flows. Hazards include ashfall, pyroclastic flows, lava avalanches, and lahars, with nearby communities such as Lumajang and Malang at risk from volcanic activity and associated hazards. The volcano’s ongoing activity poses persistent risks for aviation and local populations.