Mount Semeru Erupts Again Tonight, Volcanic Ash Plume Approximately 1,000 Meters High

Mount Semeru in East Java erupted again on Monday (8/12/2025) at 21:24 WIB. In the last week, Mount Semeru has erupted 9 times.

According to 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 1,000 meters above the peak (4,676 meters above sea level).

The ash column was observed to be white to gray with thick intensity towards the southwest. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 182 seconds.

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According to MAGMA Indonesia's volcano activity report, Mount Semeru's activity level is at Level III (Alert). Seismicity observations on December 8, 2025, from 12:00-18:00 WIB, showed 43 eruption earthquakes with amplitudes of 10-22 millimeters and durations of 58-160 seconds.

Then, 6 rockfall earthquakes with amplitudes of 2-5 mm and durations of 23-48 seconds, and 1 exhalation earthquake with an amplitude of 5 millimeters and a duration of 58 seconds occurred.

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 due to the potential for expansion of hot clouds and lava flows up to 17 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 7,264 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,987 events.

(Read: Not Jakarta, These Are the Areas with the Worst Air Quality in Indonesia (Wednesday, June 7, 2023))