Semeru rain lahar threatens Besuk Kobokan for 17 kilometers

The threat from rain-triggered lahars from Mount Semeru has increased in Lumajang, East Java, after rainfall rose over the past five days. BPBD Lumajang asked residents not to carry out activities within a 500-meter radius of riverbanks along Besuk Kobokan because the lahar flow and the expansion of hot clouds could reach as far as 17 kilometers from the summit. The warning also applies to residents still crossing near the river flow and to sand miners in the affected area. In Sumberwuluh village, Candipuro district, Balai Besar Wilayah Sungai Brantas has built one consolidation dam and six flow-directing embankments along 2,500 meters to hold back volcanic material. By early October 2026, the physical progress of the lahar control project was reported at 25.2 percent.