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 an altitude of 4 300 m (14 100 feet) above sea level at 15:10 UTC on November 1, 2025. The advisory was issued by the Darwin VAAC at 15:30 UTC on the same day.

Ash was reported between the surface and flight level 140, equivalent to approximately 4 300 m (14 100 feet). The advisory notes that volcanic ash was not identifiable on satellite imagery due to meteorological cloud cover. Ground reports indicated intermittent discrete eruptions were ongoing, and ash movement and height were determined based on ground observations and model guidance. The current Aviation Color Code is Orange. The ash cloud was moving southwest at a speed of approximately 9 km/h (6 mph).

According to the Smithsonian/USGS Weekly Volcanic Activity Report for late September 2025, activity at Semeru continued with daily eruptive events. Gray and white-and-gray ash plumes rose 400–900 m (1 300–3 000 feet) above the summit, and emissions drifted in multiple directions. The public was advised to remain at least 3 km (1.9 miles) from the summit, with expanded exclusion zones on the southeast and near major drainages due to hazards.

Semeru is an active stratovolcano located in East Java, Indonesia. It is the highest mountain on Java and frequently erupts, producing volcanic ash plumes, lava flows, and pyroclastic flows. Hazards associated with Semeru include ashfall, pyroclastic flows, lava avalanches, and lahars, particularly threatening communities along the river valleys on the volcano’s southern and southeastern flanks, including towns such as Lumajang and Pronojiwo.