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

A volcanic ash advisory was issued for Semeru volcano, Indonesia, after ash emissions were reported reaching up to 4.6 km (15 000 feet) above sea level at 01:41 UTC on July 8, 2025. The ash was observed moving west at an estimated speed of 15 knots based on the latest available data.

The observed ash cloud extended from the surface to FL150, with coordinates indicating movement towards the west. The advisory noted that volcanic ash was not identifiable on satellite imagery due to meteorological cloud cover; however, ground reports confirmed intermittent discrete emissions ongoing at the volcano. The Aviation Color Code is currently Orange. Forecasts projected continued movement of the ash cloud to the west over the following 18 hours, with updates pending further observation.

According to the latest Smithsonian / USGS Weekly Volcanic Activity Report, Semeru continued to exhibit activity during June 25 to July 1, 2025, with multiple daily eruptive events registered by the seismic network. Although visual observations were sometimes hampered by weather conditions, ash plumes recently rose 500–600 m above the summit, and the public was advised to maintain exclusion zones due to ashfall, lahar, and pyroclastic flow hazards.

Semeru is a stratovolcano and the highest volcano on Java, Indonesia. It is known for frequent explosive eruptions and lava flows, producing hazards that include ashfall, pyroclastic flows, and lahars. The nearby population centers of Lumajang and Malang may be at risk during larger eruptive events or under specific wind conditions.