Warning! Mount Semeru Erupts Again This Morning (Saturday, December 20, 2025)

Mount Semeru in East Java erupted again on Saturday (Dec 20, 2025) at 06:40 AM WIB. In the last week, Mount Semeru has erupted 50 times.

Based on eruption information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) via the MAGMA Indonesia application, the height of the observed ash column reached 1,000 meters above the peak (4,676 meters above sea level).

The ash column was observed to be white to grey with thick intensity towards the east. The eruption was recorded on a seismograph with a maximum amplitude of 18 millimeters and a duration of 140 seconds.

(Read: Indication of Forest and Land Fire Area in East Kalimantan until June 2025)

According to the MAGMA Indonesia volcano activity report, Mount Semeru's activity level is at Level III (Alert). Seismic observations on December 20, 2025, from 00:00-06:00 AM WIB, showed 50 eruption earthquakes with amplitudes of 13-22 millimeters and durations of 68-141 seconds. Additionally, there were 7 rockfall earthquakes with amplitudes of 4-7 mm and durations of 41-76 seconds.

PVMBG advises against any activity in the southeast sector along Besuk Kobokan, as far as 13 kilometers from the peak (eruption center). Beyond that distance, people should not engage in activities within 500 meters from the riverbanks along Besuk Kobokan, as there is a potential for hot cloud expansion and lava flows up to 17 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 7,425 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 3,074 occurrences.

(Read: 55 Disasters Occurred in Mid-September 2023, Forest and Land Fires Dominated)