Mount Semeru, located in East Java, once again showed increased volcanic activity on Thursday (11/6/2026). Between 00:41 WIB and 11:13 WIB, the highest mountain on Java Island was recorded to have erupted six times.
Sigit Rian Alfian, an officer at the Mount Semeru Observation Post, reported that the highest intensity eruption occurred at 08:03 WIB. At that moment, the ash column reached a height of 1,000 meters above the peak, or approximately 4,676 meters above sea level (masl). Thick white-to-gray volcanic material was observed drifting toward the southwest sector.
Seismograph data recorded fairly intense seismic activity during the observation period from 06:00 to 12:00 WIB. In addition to 18 eruption earthquakes, rockfall, gust, harmonic, and distant tectonic earthquakes were also recorded, indicating dynamics beneath the crater's surface.
Currently, Mount Semeru's status remains at Level III (Alert). Relevant authorities emphasized a strict prohibition against any activities within a five-kilometer radius of the crater, as well as staying away from the southeastern sector along Besuk Kobokan up to a distance of 13 kilometers from the summit.
Residents are urged to remain vigilant against the threat of pyroclastic flows, lava flows, and potential cold lahar floods that could flow through river valleys originating at the summit, such as Besuk Bang, Besuk Kembar, and Besuk Sat. The public is asked to continuously monitor official information from authorities to anticipate safety risks.
