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

A volcanic ash advisory was issued for Semeru volcano in Indonesia following ongoing ash emissions observed at 16:30 UTC on July 15, 2025. The Darwin Volcanic Ash Advisory Centre (VAAC) reported that volcanic ash rose to an altitude of 4.6 km (15 000 feet) above sea level, with the ash cloud moving to the west-northwest.

According to the advisory, the ash was not identifiable in the most recent satellite imagery due to meteorological cloud cover. However, satellite data and ground-based reports from the last 12 hours confirmed the ongoing nature of the emissions. The altitude of the ash and the forecast movement of the plume were determined through satellite imagery, ground reports, and model guidance. The current Aviation Color Code is Orange, signifying heightened volcanic activity with potential for ash in the atmosphere.

Recent reports from the Global Volcanism Program confirm that Semeru continued to exhibit frequent eruptive activity from July 2–8, 2025, with multiple daily eruptive events detected by seismic networks. Although visual observations were sometimes limited, dense white-and-gray ash plumes rose 400–1 000 meters above the summit during this period, with ash dispersing in several directions. The public is advised to maintain a distance of at least 3 km from the summit in all directions and to avoid river drainages due to the risk of lahars and pyroclastic flows.

Semeru is a stratovolcano located in East Java, Indonesia. Known for its near-constant activity, hazards at Semeru include ashfall, pyroclastic flows, lava flows, and lahar (volcanic mudflow) events. Populated communities, such as those around Lumajang and Malang, are situated near the base of the volcano and could be at risk from significant eruptive episodes.