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

Volcanic ash emissions were reported from Semeru volcano, Indonesia, with ash observed reaching up to 4.6 km (15 000 feet) above sea level on June 20, 2025. The event was recorded following a volcanic ash eruption at 10:39 UTC, as indicated by the latest advisory from the Darwin Volcanic Ash Advisory Centre.

The ash cloud, associated with this activity, was reported to be moving west at approximately 9 km per hour (5 knots). The observed volcanic ash was not identifiable in satellite imagery due to the presence of meteorological clouds. Ground-based reports from the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM) indicated that discrete ash emissions were ongoing, and the Aviation Color Code is currently Orange. Model guidance was used to estimate the ash height and movement. No ash cloud was detected in satellite imagery during this advisory period.

According to the Smithsonian’s Global Volcanism Program, Semeru remains active with multiple eruptive events occurring daily. During the week of May 21–27, 2025, daily white-and-gray ash plumes were observed rising 400–1 200 m above the summit, drifting in various directions. The public has been advised to maintain a distance of at least 3 km from the summit in all directions, and up to 8 km on the southeast side, due to persistent lahar, avalanche, and pyroclastic flow hazards.

Semeru is Indonesia’s highest volcano and is classified as a stratovolcano. The volcano frequently produces explosive eruptions generating ashfall, pyroclastic flows, and lahars. Local communities and settlements near the volcano, including the town of Lumajang, may be subject to volcanic hazards, and ongoing monitoring and preparedness are crucial for populations living in proximity to Semeru.