LUMAJANG - Mount Semeru in East Java erupted again with an eruption as high as 1,000 meters above the peak on Saturday morning.
"There was an eruption of Mount Semeru on Saturday, December 20, 2025, at 07.30 WIB with an observed eruption column height of around 1,000 meters above the peak or 4,676 meters above sea level (msl)," said Mount Semeru Observation Post Officer, Sigit Rian Alfian, reported by ANTARA, Saturday, December 20.
According to him, the column of mountain ash on the border of Lumajang and Malang Regencies was observed to be white to gray in color with thick intensity towards the east and the eruption was recorded on the seismograph with a maximum amplitude of 18 mm with a duration of 130 seconds.
Based on data from officers, on Saturday from 00.22 WIB to 07.30 WIB, it was recorded that Mount Semeru had 11 eruptions with eruption heights ranging from 700 meters to 1,100 meters above the peak.
The height of the eruption reached 1,100 meters above the peak occurred during the eruption at 05.35 WIB and the ash column was observed to be white to gray with medium intensity towards the northeast. When the report was made, the eruption was still ongoing.
Based on the observation of the earthquake, the activity of Mount Semeru is still dominated by eruptive earthquakes recorded from 00.00 to 06.00 WIB as many as 50 times of eruptive/eruptive earthquakes with an amplitude of 13-22 mm and earthquake duration of 68-141 seconds, and 7 times of aftershocks with an amplitude of 4-7 mm and earthquake duration of 41-76 seconds.
Visual observations, the highest mountain on Java, were clearly visible and the crater's smoke was not observed, as well as clear weather, weak winds to the north and northeast.
Sigit explained that Mount Semeru's status was still at Level III or alert, so the Center for Volcanology and Geological Hazard Mitigation (PVMBG) gave a number of recommendations, namely not to carry out any activities in the southeast sector along Besuk Kobokan, as far as 13 km from the peak (center of the eruption).
"Outside this distance, people do not carry out activities at a distance of 500 meters from the river bank (river border) along Besuk Kobokan because they have the potential to be hit by the expansion of the hot cloud and lava flow up to a distance of 17 km from the peak," he said.
He urged the public not to carry out activities within a radius of 5 km from the crater / peak of Mount Semeru because they were prone to the danger of stone throwing (pijar).
The public is also asked to be aware of the potential for hot cloud discharge (APG), lava discharge, and lahar along the river/valley flows upstream at the peak of Mount Semeru, especially along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as the potential for lahar in small rivers that are tributaries of Besuk Kobokan.
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