Mount Semeru Erupts Again This Morning (Tuesday, October 21, 2025)

Mount Semeru in East Java erupted again on Tuesday (October 21, 2025) at 05:32 AM WIB. In the last week, Mount Semeru has erupted 13 times.

Based on eruption information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) via the MAGMA Indonesia application, the observed ash column height reached 700 meters above the peak (4,376 meters above sea level).

The ash column was observed to be white to grey with moderate intensity towards the south. Mount Semeru's eruption was still ongoing when this report was made.

(Read: Due to Forest Fires, ISPA Cases in South Kalimantan Reached 189 Thousand as of September 2023)

According to MAGMA Indonesia's volcano 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/explosion earthquakes with amplitudes of 10-23 millimeters and earthquake durations of 64-154 seconds.

Furthermore, there were 40 avalanche earthquakes with amplitudes of 2-10 mm and durations of 30-110 seconds, and 15 exhalation earthquakes with amplitudes of 2-7 millimeters and durations of 43-97 seconds.

PVMBG urges against any activity in the southeast sector along Besuk Kobokan, as far as 8 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 13 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 6,731 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,653 occurrences.

(Read: Forest Fire Hotspots in South Sumatra Increased in Mid-October 2023)