Volcanic ash emissions at Semeru volcano reach 4.6 km (15 000 feet) a.s.l., Indonesia

An ash advisory issued for Semeru volcano, Indonesia, reports volcanic ash emissions reaching up to flight level 150, or approximately 4.6 km (15 000 feet) above sea level, as observed at 23:00 UTC on June 18, 2025. The volcano continues to experience regular eruptions, according to the latest information from the Darwin VAAC and the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM).

The observed ash cloud was last reported in satellite imagery and ground reports to have reached up to 800 m above the summit, with the summit itself at 3 657 m (11 998 feet) elevation. Volcanic ash is currently reported at the surface to FL150 (approximately 4.6 km or 15 000 feet) and regular eruptions persist, although visual confirmation is difficult due to meteorological cloud cover. The current Aviation Color Code is Orange. Forecasts suggest ash clouds could affect areas east and southeast of the volcano for the next 18 hours.

According to the Smithsonian / USGS Weekly Volcanic Activity Report for late May 2025, Semeru has had multiple daily eruptive events, with ash plumes rising 400–1 200 m above the summit and drifting in multiple directions. Alert Level 2 remains in effect, with the public advised to remain at least 3 km from the summit in all directions due to ongoing hazards.

Semeru is an active stratovolcano located in East Java, Indonesia, and is the highest volcano on the island. Known hazards include ashfall, pyroclastic flows, and lahars, with the nearby settlements of Pronojiwo and the city of Lumajang at potential risk during significant eruptive episodes. The volcano frequently produces explosive eruptions that pose risks to both local populations and aviation.