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 21:10 UTC on October 24, 2025. The advisory was issued by the Darwin VAAC at 21:30 UTC on the same day.

Ash cloud was reported between the surface and flight level 140 (approximately 4 300 m or 14 100 feet) based on ground observations and model guidance. The ash was moving toward the southwest at approximately 19 km/h (12 mph). Satellite detection (Himawari-8) was not possible due to meteorological cloud cover. The current Aviation Color Code is Orange.

According to the Global Volcanism Program’s most recent weekly report, daily eruptive events were recorded at Semeru during September 24–30, 2025. Ash plumes rose 400–900 m (1 300–3 000 feet) above the summit, and the public was advised to stay at least 3 km (1.9 miles) away from the summit in all directions, 8 km (5 miles) to the southeast, and avoid river drainages due to lahar and pyroclastic flow risks.

Semeru is a stratovolcano and the highest volcano on Java, Indonesia. It is known for frequent explosive eruptions producing ash plumes, lava flows, and pyroclastic flows. Populations in nearby areas such as Lumajang and Malang may be at risk from ashfall, pyroclastic flows, and lahars. The volcano remains under regular observation due to its persistent activity and proximity to inhabited areas.