Head of the Geological Agency, Muhammad Wafid, stated that the eruption was detected on Thursday evening by officers from the Dempo Volcano Observatory (PGA) in Pagar Alam.
“Based on analysis, this was a phreatic eruption, which can occur suddenly without clear volcanic symptoms,” he said in Jakarta on Friday afternoon.
According to the agency, Mount Dempo spewed a 1,200-meter-high ash column that was gray, thick, and leaned northward. The eruption was recorded on a seismogram with a maximum amplitude of 30 millimeters and lasted nearly four minutes.
Wafid noted that Mount Dempo—located on the border of Lahat District, Empat Lawang District, and Pagar Alam City—has shown increased seismic activity since early July 2025.
This activity has been accompanied by deformation of the mountain’s shape, with signs of bulging or inflation, indicating magma movement toward the surface.
Wafid urged residents, climbers, and tourists to avoid a 1-kilometer radius around Mount Dempo’s crater and a 2-kilometer radius in the northern sector. “This zone is at risk of material ejection and toxic gases from a phreatic eruption,” he said.
He emphasized that, based on visual and instrumental data, Mount Dempo remains at Alert Level II.
The Geological Agency, through the Center for Volcanology and Geological Hazard Mitigation (PVMBG) and the Dempo Volcano Observation Post, continues to monitor the volcano’s activity.
Authorities have urged the public to stay calm, avoid spreading unverified information, and follow all evacuation instructions from local officials.
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Translator: M. Riezko Bima Elko Prasetyo, Arie Novarina
Editor: M Razi Rahman
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