People look at a pyroclastic flow during the eruption of Mount Semeru in Lumajang, East Java, on November 19, 2025. - AFP
LUMAJANG, Indonesia: Mount Semeru, located on the border of Lumajang and Malang Districts, East Java, erupted on Sunday night (Jan 11), sending pyroclastic flows as far as five kilometres from the summit, reported Antara news agency.
"Mount Semeru erupted at 10.25 pm local time. The eruption consisted of a pyroclastic flow with a distance of approximately five km," an officer at the Mount Semeru Observation Post, Sigit Rian Alfian, said in a written report.
The eruption column - locally known as hot clouds - was observed to be approximately 2,000 metres above the summit, or 5,676 metres above sea level.
This latest activity follows a period of heightened unrest for the volcano, which has remained frequently active for several years.
"The ash column was observed to be white to grey in colour, with thick intensity toward the east and southeast," Alfian added.
The eruption of Mount Semeru was recorded on seismographs with a maximum amplitude of 27 millimetres and a duration of 696 seconds.
Mount Semeru remains at Level III alert status. Authorities have advised the public to refrain from all activities in the south-eastern sector along Besuk Kobokan, within 13 km of the summit.
Beyond that distance, people are prohibited from engaging in activities within 500 metres of the Besuk Kobokan riverbanks due to the risk of expanding pyroclastic and lava flows, which could reach up to 17 km from the peak.
"The public is advised not to engage in activities within a five km radius of the crater/peak of Mount Semeru due to the risk of ejected incandescent rocks," he continued.
Residents are also warned of potential pyroclastic flows and lava flows moving through rivers and valleys that originate from the summit of Mount Semeru, particularly in Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, including smaller tributaries of Besuk Kobokan that may also be affected by the lava.- Bernama-Antara
