Ash plume from Semeru volcano reaches 4.6 km (15 000 feet) a.s.l., Indonesia

Semeru volcano in Indonesia produced a volcanic ash (VA) plume that reached flight level FL150, or approximately 4.6 km (15 000 feet) above sea level, according to a VAAC Darwin advisory issued at 23:10 UTC on June 19, 2025. The ash emission was first reported based on ground observations at 17:45 UTC on June 19, with the plume moving southwest at a speed of 5 knots.

The observed ash cloud extended from the surface up to 4.6 km (15 000 feet) and was traced southwest of the volcano. Due to meteorological clouds, the ash cloud was not identifiable on satellite imagery; however, regular ground-based reports from the Center for Volcanology and Geological Hazard Mitigation (CVGHM) confirmed ongoing discrete ash emissions. The Aviation Color Code is currently Orange. Forecast maps indicate a persistent ash cloud at the same altitude for at least the next 18 hours.

The latest Smithsonian/USGS Weekly Volcanic Activity Report indicates that Semeru continued multiple daily eruptive events in late May 2025. Ash plumes frequently rose 400–1 200 m above the summit and drifted in various directions. The Alert Level remained at 2 (on a scale of 1–4), with public access restrictions within a 3 km radius of the summit and up to 8 km southeast due to ongoing hazards like lahars and pyroclastic flows.

Semeru is the highest volcano on Java and is classified as a stratovolcano. It is known for persistent explosive activity, lava domes, ash falls, pyroclastic flows, and lahars. Settlements at risk include the town of Lumajang and surrounding agricultural communities located on the volcano’s southern and southeastern flanks.