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

An ash eruption occurred at Semeru volcano, Indonesia, as reported by the Darwin VAAC. The event was last reported at 22:29 UTC on June 22, 2025, with observations of discrete volcanic ash emissions continuing according to local ground reports. The eruption has resulted in ash plumes being registered and tracked for aviation and hazard assessment purposes for the region.

The reported volcanic ash cloud reached an altitude of FL150, approximately 4 600 m (15 000 feet) above sea level, and was moving toward the southwest at around 18.5 km/h (10 knots). Due to meteorological cloud cover, the ash could not be identified in satellite imagery at the observation time, but regular ground-based reports confirmed ongoing emissions. Ash position and movement details, along with forecasts for the following 18 hours, were based on ground data and model guidance. The current Aviation Color Code is Orange, indicating ongoing volcanic activity that may impact aviation.

According to the most recent Smithsonian / USGS Weekly Volcanic Activity Report, Semeru displayed ongoing eruptive activity with daily ash plumes rising 400-1 200 m above the summit during the previous monitoring period. Multiple eruptive events were recorded, and authorities maintained Alert Level 2, advising the public to remain at least 3 km away from the summit and to observe additional exclusion zones due to hazards including lahars and pyroclastic flows.

Semeru is the highest volcano on Java and is known as a stratovolcano, frequently producing explosive eruptions, ash plumes, pyroclastic flows, and lava avalanches. Hazards primarily include ashfall, pyroclastic flows, and lahars, which may affect nearby settlements such as Pronojiwo and Lumajang. The region is regularly monitored due to persistent volcanic activity and potential impacts on aviation and communities downslope from the volcano.