Mount Semeru erupts with 900-metre explosion

Lumajang, East Java - Mount Semeru, on the border of Lumajang and Malang Regencies, East Java, erupted with an explosion reaching 900 metres above the summit on Saturday night.

“An eruption of Mount Semeru occurred this Saturday at 19:09 WIB, with the eruption column observed at approximately 900 metres above the summit,” stated Sigit Rian Alfian, an officer at the Mount Semeru Observation Post, in a written report received in Lumajang.

According to him, the ash column was observed to be white to grey in colour with thick intensity, moving towards the northeast.

“The eruption was recorded on the seismograph with a maximum amplitude of 23 mm and a duration of 140 seconds,” he said.

Based on the data, Mount Semeru experienced 11 eruptions on Saturday between 03:30 WIB and 19:10 WIB, with explosion heights ranging from 500 metres to 900 metres above the Mahameru summit.

“Beyond those distances, 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 summit,” he added.

The public is prohibited from conducting activities within a five-kilometre radius of the Mount Semeru crater/summit due to the danger of volcanic rock fragments (incandescent debris).

Residents are also urged to remain vigilant regarding the potential for pyroclastic clouds, lava flows, and lahars along the rivers and valleys originating from the peak 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,” Sigit said.