Mount Semeru erupts, sending ash column 1.2 km high accompanied by moderate rumbling

Mount Semeru, located on the border of Lumajang and Malang regencies in East Java, erupted again on Monday, producing a column of volcanic ash that reached 1.2 kilometres above the peak. The eruption occurred at 16.39 Western Indonesian Time, with the ash column observed rising to approximately 4,876 metres above sea level. According to Sigit Rian Alfian, an officer at the Mount Semeru Observation Post, the ash column was white to grey in colour with thick intensity, drifting towards the northeast and east. The eruption was recorded on a seismogram with a maximum amplitude of 22 millimetres and a duration of roughly 2 minutes and 9 seconds. Petugas noted that the 3,676-metre-high volcano erupted nine times on Monday, from midnight until 19.23 Western Indonesian Time, with eruption heights ranging between 500 and 1,200 metres above the summit. The Head of the Lumajang Regional Disaster Management Agency, Isnugroho, confirmed that his team had received information from the Centre for Volcanology and Geological Hazard Mitigation regarding the eruption, which was accompanied by moderate rumbling sounds. He stated that there had been no direct impact on the community, but officers remained on standby at the Curahkobokan and Oro-oro Ombo monitoring posts to observe the volcano’s activity. Mount Semeru remains at Level III alert status. The public is advised not to conduct any activities in the southeastern sector along Besuk Kobokan, within 13 kilometres of the summit. Beyond that distance, people are prohibited from carrying out activities within 500 metres of the riverbank along Besuk Kobokan, due to the potential for expansion of hot clouds and lava flows up to 17 kilometres from the peak. The public is also prohibited from engaging in activities within a five-kilometre radius of the crater or summit, as the area is prone to the danger of incandescent rock projectiles. Authorities urge residents to remain vigilant against the potential for hot clouds, lava avalanches, and lahars along river valleys originating from the summit, particularly along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as the potential for lahars in small streams that are tributaries of Besuk Kobokan.