Mount Semeru Erupts Again Tonight (Sunday, December 21, 2025)

Mount Semeru in East Java erupted again on Sunday (21/12/2025) at 09:31 PM WIB. In the last week, Mount Semeru has erupted 74 times.

Citing 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.

Eruption visuals were not observed. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 132 seconds.

(Read: Area of Rice Fields, Land, and Gardens in Indonesia Damaged by Floods 2020-2024)

According to MAGMA Indonesia's volcano activity report, Mount Semeru's activity level is at Level III (Alert). Seismicity observations on December 21, 2025, at 12:00-18:00 WIB showed 30 eruption/explosion earthquakes with amplitudes of 12-22 millimeters and earthquake durations of 91-114 seconds.

Subsequently, there were 3 rockfall earthquakes with amplitudes of 5-7 mm and durations of 47-56 seconds, and 1 harmonic tremor with an amplitude of 11 millimeters and a duration of 69 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 expansion of hot clouds and lava flows up to 17 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 7,463 volcano eruptions across Indonesia. Mount Semeru in East Java has erupted the most with 3,098 occurrences.

(Read: Distribution of Fatalities Due to Floods and Landslides in North Sumatra (December 9, 2025))