Volcanic ash from Semeru volcano observed at 4 600 m (15 000 feet) a.s.l., Indonesia

Volcanic ash from Semeru in Indonesia was observed at 4 600 m (15 000 feet) above sea level at 21:20 UTC on November 5, 2025. The advisory was issued by Darwin VAAC at 21:40 UTC.

According to the advisory, ash was reported at a maximum altitude of 4 600 m (15 000 feet) moving toward the northeast at approximately 9 km/h (5 mph). The ash was not identifiable in satellite imagery due to meteorological cloud cover. Recent ground reports indicated intermittent discrete eruptions were ongoing. The current Aviation Color Code is Orange.

During the week of September 24-30, 2025, the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported daily eruptive events at Semeru. White-and-gray or gray ash plumes were observed rising 400–900 m (1 300–3 000 feet) above the summit and drifting in various directions. The Alert Level remained at 2, and the public was advised to avoid areas within 3 km (1.9 miles) of the summit and 8 km (5 miles) to the southeast due to potential lahar, avalanche, and pyroclastic flow hazards.

Semeru is a stratovolcano located in East Java, Indonesia, and is the highest volcano on the island. Known hazards at Semeru include ashfall, pyroclastic flows, lava flows, and lahars. Settlements in the region, including the town of Lumajang located roughly 20 km (12 miles) southeast, are at potential risk from volcanic hazards, particularly lahars and ashfall during eruptive periods.