Volcanic ash from Semeru volcano observed at 4 300 m (14 100 feet) a.s.l., Indonesia

Volcanic ash from Semeru volcano in Indonesia was observed at an altitude of 4 300 m (14 100 feet) above sea level at 15:30 UTC on October 13, 2025. The advisory was issued by the Darwin VAAC at 16:00 UTC on the same day.

According to the VAAC advisory, the ash cloud was reported from the ground, as it was not identifiable on recent satellite imagery due to meteorological cloud cover. The ash was moving west at around 37 km/h (23 mph) based on ground reports and model guidance. The observed and forecast ash altitude was FL140, which corresponds to approximately 4 300 m (14 100 feet) above sea level. The current Aviation Color Code is Orange.

Recent reports from the Global Volcanism Program indicate that activity at Semeru continued during late September 2025, with daily eruptive events producing white-and-gray or gray ash plumes rising 400–900 m (1 300–3 000 feet) above the summit and drifting in multiple directions. The Alert Level remained at 2, and the public was warned to stay at least 3 km (1.9 miles) away from the summit, 8 km (5 miles) southeast, 500 m (1 600 feet) from the banks of the Kobokan drainage up to 13 km (8.1 miles) from the summit, and to avoid other hazardous drainages.

Semeru is a stratovolcano located in East Java, Indonesia, and is the highest volcano on the island. Known hazards include ashfall, pyroclastic flows, lava flows, and lahars. Nearby settlements such as the town of Lumajang, located to the southeast, and villages along river drainages are at risk during significant eruptive episodes. The volcano’s frequent activity poses ongoing risks to both local populations and aviation in the region.