Mount Semeru Erupts Again This Afternoon (Monday, December 8, 2025)

Mount Semeru in East Java erupted again on Monday (8/12/2025) at 02:22 PM Western Indonesian Time (WIB). In the last week, Mount Semeru has erupted 8 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 or 4,676 meters above sea level.

The ash column was observed to be gray with thick intensity towards the north. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 108 seconds.

(Read: There Were 137 Natural Disasters Towards the End of January 2024, Most of Which Were Floods)

According to the MAGMA Indonesia volcano activity report, Mount Semeru's activity level is at Level III (Siaga/Alert). Seismicity observations on December 8, 2025, from 06:00 AM to 12:00 PM WIB showed 46 eruption tremors/earthquakes with amplitudes of 12-22 millimeters and durations of 87-127 seconds.

Subsequently, there was 1 rockfall earthquake with an amplitude of 6 mm and a duration of 40 seconds, and 2 exhalation earthquakes with amplitudes of 4-6 millimeters and durations of 48-64 seconds.

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, people 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 7,262 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,986 events.

(Read: The Number of Fatalities from Natural Disasters in Indonesia Skyrocketed in 2024)