Following Anak Krakatau, Mount Semeru Erupts This Morning

Mount Semeru in Lumajang, East Java, erupted on Sunday morning, 6 September 2026. According to data from the Centre for Volcanology and Geological Hazard Mitigation (PVMBG), Mount Semeru experienced an eruption consisting of an ash plume reaching 1,000 metres above the summit.

“The eruption of Mount Semeru occurred at 07:51 WIB, with an observed eruption column height of approximately 1,000 metres above the peak, or 4,676 metres above sea level (masl),” said Sigit Rian Alfian, an officer at the Mount Semeru Observation Post, in a written report received in Lumajang, East Java, on Sunday.

Currently, the volcanic activity of Mount Semeru is at Level III, or Alert status. He detailed that the observed ash column was white to grey in colour with thick intensity, moving towards the east.

“The eruption was recorded on the seismograph with a maximum amplitude of 23 mm and a duration of 102 seconds,” he added.

Following the activity of Mount Semeru, PVMBG advises the public to refrain from outdoor activities, particularly in the south-eastern sector along Besuk Kobokan, within 13 km of the summit which is the centre of the eruption.

“Outside of that distance, the public must also avoid activities within 500 metres of the riverbanks along Besuk Kobokan, as there is a potential for the expansion of hot clouds and lava flows up to 17 km from the summit,” said Sigit.

The public is also prohibited from conducting activities within a 5 km radius of the Mount Semeru crater/summit due to the danger of volcanic rock fragments (pyroclastic material).

Sigit urged the community to remain vigilant regarding the potential for hot clouds, lava flows, and lahars along the river flows or valleys originating from the peak of Mount Semeru.

“Particularly along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as the potential for lahars in small rivers that are tributaries of Besuk Kobokan,” Sigit concluded.