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 an altitude of 4 300 m (14 100 feet) above sea level at 03:10 UTC on November 2, 2025. The advisory was issued by the Darwin VAAC at 03:30 UTC on the same day.

According to the VAAC advisory, the ash cloud was reported between the surface and FL140, equivalent to about 4 300 m (14 100 feet). The cloud was moving toward the southwest at 9 km/h (5.6 mph). Ash was not identifiable in satellite imagery due to meteorological cloud, but ground reports indicated intermittent discrete eruptions ongoing. Ash height and movement were determined from ground observations and model guidance. The current Aviation Color Code is Orange.

The Global Volcanism Program reports that activity continued at Semeru during the week of September 24–30, 2025, with daily eruptive events detected by the seismic network. Ash plumes rose 400–900 m above the summit and drifted in several directions. The public was advised to maintain a distance of at least 3 km from the summit in all directions, with expanded exclusion zones on certain drainages.

Semeru is a stratovolcano and the highest mountain on Java, Indonesia. Known hazards from this volcano include ashfall, pyroclastic flows, lava avalanches, and lahars. The surrounding region is densely populated, with the town of Lumajang located about 30 km (19 miles) southeast of the summit and several smaller villages situated within the hazard zones.