Warning! Mount Semeru Erupts Again Tonight (Tuesday, October 21, 2025)

Mount Semeru in East Java erupted again on Tuesday (10/21/2025) at 23:57 WIB. In the last week, Mount Semeru has erupted 22 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 was approximately 800 meters above the peak (4,476 meters above sea level).

The ash column was observed to be white to grey with thick intensity towards the west. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 128 seconds.

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According to MAGMA Indonesia's volcanic activity report, Mount Semeru's activity level is at Level II (Alert). Seismic observations on October 21, 2025, from 00:00-23:59 WIB showed 55 eruption/explosive earthquakes with amplitudes of 10-23 millimeters and earthquake durations of 64-154 seconds.

Subsequently, there were 40 rockfall earthquakes with amplitudes of 2-10 mm and durations of 30-110 seconds, and 15 emission earthquakes with amplitudes of 2-7 millimeters and durations of 43-97 seconds.

PVMBG advises against any activity in the southeast sector along Besuk Kobokan, as far as 8 kilometers from the peak (eruption center). Beyond this distance, the public is advised not to engage in activities within 500 meters from the riverbanks along Besuk Kobokan, as there is potential to be affected by the expansion of pyroclastic flows and lahar flows up to 13 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 6,747 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,662 events.

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