Mount Semeru Erupts on Thursday Afternoon, Activity Level at Alert

Mount Semeru in East Java erupted again on Thursday (21/8/2025) at 17.27 WIB. In the last week, Mount Semeru has erupted 22 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.

The visual of the eruption was not observed. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 108 seconds.

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According to the MAGMA Indonesia volcano activity report, Mount Semeru''s activity level is at Level II (Alert). Seismicity observations on August 21, 2025, from 00.00-23.59 WIB showed 42 eruption/explosion earthquakes with amplitudes of 10-22 millimeters and durations of 58-146 seconds.

Then, 2 rockfall earthquakes with amplitudes of 2-3 mm and durations of 65-75 seconds, and 14 exhalation earthquakes with amplitudes of 3-8 millimeters and durations of 32-85 seconds.

PVMBG urges not to conduct any activities in the southeast sector along Besuk Kobokan, as far as 8 kilometers from the peak (eruption center). Beyond that distance, the public should not engage in activities within 500 meters from the riverbanks (river borders) along Besuk Kobokan due to the potential for expansion of hot clouds and lava flows up to 13 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 5,726 volcanic eruptions across Indonesia. Mount Semeru in East Java has erupted the most with 2,297 occurrences.

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