Inp.polri.go.id - Lumajang. Mount Semeru, Indonesia’s highest volcano, located in Lumajang, East Java, erupted on Monday morning (22/9/2025) with an ash column rising 700 meters above its summit.

“The eruption occurred at 5.28  am local time, with the ash column reaching 4,376 meters above sea level,” said Sigit Rian Alfian, an officer at Mount Semeru’s monitoring post, in a written report, as quoted by antaranews.com. 

He added the ash appeared white to gray, drifting southwest and west, while seismographs recorded a maximum amplitude of 22 mm lasting 139 seconds.

Earlier eruptions were also detected at 0.54, 2.43, and 4.44, with ash columns reaching between 500 and 700 meters.

Semeru remains at Alert Level II (Waspada). Authorities have prohibited activities within eight kilometers southeast of the crater, especially along Besuk Kobokan, and advised against any activity within three kilometers of the summit due to risks of pyroclastic flows, lava avalanches, and lahars. 

Residents are urged to stay vigilant for volcanic hazards in river valleys downstream.

(mg/inp/pr/rs)