Ash cloud from Semeru volcano reaches 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 15:50 UTC on October 19, 2025. The advisory was issued by the Darwin VAAC at 16:10 UTC on the same date.

The ash cloud was reported to extend from the surface up to flight level 140, which is approximately 4 300 m (14 100 feet). The volcanic ash was forecast to drift towards the southwest at 19 km/h (12 mph). Ash was not identifiable from satellite imagery due to meteorological cloud cover, but intermittent discrete eruptions were expected based on ground reports and model guidance. The current Aviation Color Code is Orange.

According to the Smithsonian / USGS Weekly Volcanic Activity Report for September 24–30, 2025, Semeru exhibited near-daily eruptive events, with white-and-gray or gray ash plumes rising 400–900 m above the summit and drifting in various directions. The Alert Level remains at 2. The public has been warned to stay at least 3 km (1.9 miles) from the summit in all directions, 8 km (5 miles) to the southeast, 500 m (1 600 feet) from the banks of the Kobokan drainage as far as 13 km (8 miles) from the summit, and to avoid other drainages due to lahar, avalanche, and pyroclastic flow hazards.

Semeru is a stratovolcano located in East Java, Indonesia, and is one of the country’s most active volcanoes. Its main hazards are ashfall, lava flows, pyroclastic flows, and lahars. Settlements at risk include the city of Lumajang and surrounding villages located within a few tens of kilometers (miles) of the volcano’s slopes. The volcano’s frequent activity necessitates continuous monitoring and the implementation of hazard zones to protect local populations.