Lumajang, Jawa Timur, Dec. 21 -- Mount Semeru, which has entered a highly active phase over the last few years, erupted six times Sunday morning with the highest plumes reaching 1.2 kilometers above its summit in East Java.

The mountain, located on the border of Lumajang and Malang Districts, is currently at Level III (Alert) status.

"An eruption occurred on December 21, 2025, at 5:46 a.m. local time, with an observed column height of 1,200 meters above the summit," said Mount Semeru Observation Post Officer, Liswanto, in Lumajang.

The Center for Volcanology and Geological Hazard Mitigation (PVMBG) recommends the public avoid activities in the southeast sector along Besuk Kobokan, within 13 km of the summit.

Beyond that distance, peop...