Mount Semeru Erupts 30 Times in 6 Hours, Explosions Heard

Mount Semeru in Lumajang, East Java, remains at Level III or alert status. The highest volcano on the island of Java recorded 30 eruptions, some of them accompanied by explosion sounds, within a six-hour observation period.

According to a report from the Semeru Volcano Observation Post (PGA) for the period of 15 September 2026, from 00:00 to 06:00 WIB (Western Indonesia Time), 30 eruptions were recorded. Some of these eruptions were accompanied by explosion sounds ranging from weak to strong intensity.

In addition to the eruptions, Mount Semeru experienced four incandescent rock falls, eight gas emissions, and two instances of harmonic tremor. The volcano remains at Level III or alert status.

“Mount Semeru experienced 30 eruptions in 6 hours, with some eruptions accompanied by explosion sounds,” said Sigit Rian Alfian, an officer at the Semeru Volcano Observation Post, in a written report quoted by detikJatim on Tuesday (15/9/2026).

The public has been advised not to conduct any activities in the south-eastern sector along Besuk Kobokan, up to 13 kilometres from the summit of Mount Semeru. Beyond that distance, residents have also been asked not to conduct activities within a 500-metre radius of riverbanks along Besuk Kobokan.

Residents have also been urged to remain vigilant of the potential for pyroclastic density currents, lava collapses, and lahars along rivers or valleys originating at the summit of Mount Semeru.