Mount Semeru Erupts, Sending Hot Ash Clouds 4 Kilometres Downslope

Lumajang, East Java — Mount Semeru, located on the border of Lumajang and Malang Regencies in East Java, erupted accompanied by pyroclastic flows extending 4 kilometres on Thursday evening.

“An eruption of Mount Semeru occurred at 16:37 WIB, with an observed eruption column height of approximately 1,500 metres above the peak, or 5,176 metres above sea level,” stated Liswanto, an officer at the Mount Semeru Observation Post, in a written report received in Lumajang.

He noted that the ash column appeared white to grey with moderate intensity, drifting towards the southeast. The eruption was recorded on a seismogram with a maximum amplitude of 22 mm and a duration of approximately 6 minutes and 40 seconds.

“During the eruption, pyroclastic clouds occurred with a flow distance of 4 km towards Besuk Kobokan, and the eruption was still ongoing at the time the report was being prepared,” he said.

“Outside of that range, the public must also refrain from any activities within 500 metres of the riverbanks along Besuk Kobokan, as there is a potential for the expansion of pyroclastic clouds and lava flows up to 17 km from the peak,” he added.

The public is also prohibited from conducting activities within a 5 km radius of the Mount Semeru crater/peak due to the danger of volcanic ejecta (incandescent rocks).

Residents are urged to remain vigilant regarding the potential for pyroclastic clouds, lava flows, and lahars along the rivers and valleys originating from the summit 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 to Besuk Kobokan,” Liswanto concluded.