Mount Semeru Erupts Again Tonight (Monday, December 22, 2025)

Mount Semeru in East Java erupted again on Monday (12/22/2025) at 00.25 WIB. In the last week, Mount Semeru only erupted once.

Citing 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 500 meters above the peak (4,176 meters above sea level).

The ash column was observed to be white to grey with moderate intensity towards the southwest. Mount Semeru's eruption was still ongoing when this report was made.

(Read: 4.8 M Earthquake Shakes 219 Km East of Levuka,)

According to MAGMA Indonesia's volcano activity report, Mount Semeru's activity level is at Level III (Alert). Seismic observations on December 22, 2025, from 18.00-23.59 WIB showed 46 eruption tremors with amplitudes of 11-22 millimeters and durations of 67-168 seconds.

Then, 17 rockfall tremors with amplitudes of 2-7 mm and durations of 31-85 seconds, and 8 exhalation tremors with amplitudes of 3-8 millimeters and durations of 28-69 seconds occurred.

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

Throughout 2025, MAGMA Indonesia has recorded 7,465 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions with 3,099 occurrences.

(Read: 4.16 M Earthquake Shakes Mona Passage)