Volcanic ash cloud from Semeru volcano rises to 4.6 km (15 000 feet) a.s.l., Indonesia

A volcanic ash advisory issued by the Darwin VAAC reported an ash eruption at Semeru volcano, Indonesia, observed at 23:10 UTC on July 5, 2025. The eruption produced an ash cloud that was tracked moving toward the south-southwest.

The volcanic ash cloud was detected at altitudes up to flight level 150, corresponding to about 4.6 km (15 000 feet) above sea level. The ash was observed moving to the south-southwest at an estimated 15 knots. No ash was identifiable on satellite imagery due to meteorological cloud cover at the time of observation, but ground reports indicated ongoing intermittent discrete emissions. The current Aviation Color Code is Orange. Volcanic ash forecasts were issued for up to 18 hours, indicating continued drift of the ash cloud toward the south-southwest. Next advisory is due no later than 05:30 UTC on July 6, 2025.

According to reports from the Smithsonian / USGS Weekly Volcanic Activity Report, activity at Semeru continued during June 25–July 1, 2025, characterized by multiple daily eruptive events detected by seismic monitoring. On July 1, white-and-gray ash plumes rose 500–600 m above the summit and drifted southwest. The Alert Level remained at 2, with public warnings for exclusion zones around the summit and drainages at risk of lahar and pyroclastic flows.

Semeru is an active stratovolcano located in East Java, Indonesia. As the highest volcano on the island, it is well known for persistent explosive activity and periodic pyroclastic flows. Ashfall and lava flows are common hazards. Populated areas at risk include villages on Semeru’s southern and southeastern flanks such as Pronojiwo and nearby communities. Authorities maintain exclusion zones due to the ongoing threat from pyroclastic flows, lahars, and ashfall.