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 03:40 UTC on October 13, 2025. The advisory was issued by the Darwin VAAC at 04:00 UTC on the same day.

According to ground reports and model guidance, the ash cloud reached between the surface and 4 300 m (14 100 feet), moving west at approximately 46 km/h (29 mph). The latest observations were hindered by meteorological cloud cover, so the ash cloud was not visible in recent satellite imagery from Himawari-8. The current Aviation Color Code is Orange.

A recent report from the Global Volcanism Program indicated that Semeru exhibited daily eruptive events during late September 2025. White-and-gray to gray ash plumes rose 400–900 m above the summit and drifted in multiple directions. The public was advised to stay at least 3 km away from the summit, 8 km to the southeast, and remain clear of local drainages prone to lahars and pyroclastic flows.

Semeru is a stratovolcano and the highest volcano on Java, Indonesia. It is known for frequent explosive eruptions, producing ashfall, pyroclastic flows, and lahars. Close population centers, including the city of Lumajang located approximately 35 km (22 miles) to the southeast, may be affected by volcanic hazards depending on wind and flow direction.