Mount Semeru Erupts Again This Afternoon (Saturday, December 20, 2025)

Mount Semeru in East Java erupted again on Saturday (20/12/2025) at 1:52 PM WIB. In the last week, Mount Semeru has erupted 52 times.

Based on eruption information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) via the MAGMA Indonesia application, the height of the ash column was observed to be around None meters above the peak or None meters above sea level.

The eruption's visuals were not observed. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 152 seconds.

(Read: Indonesia Has the Most Active Volcanoes in the World)

According to MAGMA Indonesia's volcano activity report, Mount Semeru's activity level is at Level III (Alert). Seismicity observations on December 20, 2025, from 06:00-12:00 WIB, showed 29 eruption/explosion earthquakes with amplitudes of 10-22 millimeters and durations of 58-154 seconds.

Additionally, there were 5 avalanche earthquakes with amplitudes of 2-4 mm and durations of 39-53 seconds, and 2 exhalation earthquakes with amplitudes of 3-8 millimeters and durations of 36-77 seconds.

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

Throughout 2025, MAGMA Indonesia has recorded 7,430 volcano eruptions/explosions across Indonesia. Mount Semeru in East Java had the most eruptions, with 3,076 recorded.

(Read: Countries with the Most Active Volcanoes in the World, Indonesia Ranks First)