Mount Semeru Erupts, Spewing Ash 1,000 Metres Above Summit

Mount Semeru, located on the border of Lumajang and Malang regencies in East Java, erupted on Sunday, sending an ash column 1,000 metres above its summit. According to a written report from Mount Semeru Observation Post officer Mukdas Sofian, the eruption occurred at 11.37 a.m. Western Indonesian Time, with the ash column observed reaching approximately 1,000 metres above the peak, or 4,676 metres above sea level. The ash cloud was observed to be white to grey with thick intensity, drifting towards the southeast and south. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimetres and a duration of 170 seconds. An earlier eruption took place at 6.32 a.m., producing an ash column 500 metres above the summit, with the ash drifting northwest. That event was recorded with a maximum amplitude of 22 millimetres and a duration of 129 seconds. A third eruption occurred at 9.11 a.m., though its visual column was not observed; it was recorded on the seismograph with a maximum amplitude of 22 millimetres and a duration of 203 seconds. The volcano’s activity status remains at Level III (Alert). Authorities recommend that the public refrain from any activities in the southeast sector along Besuk Kobokan, as far as 13 kilometres from the summit. Beyond that distance, people are advised not to conduct activities within 500 metres of the riverbank along Besuk Kobokan due to the potential for expanding pyroclastic flows and lahars reaching up to 17 kilometres from the peak. The public is also prohibited from activities within a five-kilometre radius of the crater due to the danger of ejected incandescent rocks. Officials urge residents to remain vigilant against the potential for pyroclastic flows, lava avalanches, and lahars along river valleys originating at the summit, particularly along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as the potential for lahars in smaller streams that are tributaries of Besuk Kobokan.