Mount Semeru Erupts Again Today, Ash Plume Reaches 900 Meters

Mount Semeru in East Java erupted again on Monday (December 8, 2025) at 07:22 AM Western Indonesia Time (WIB). In the last week, Mount Semeru has erupted 3 times.

Based on eruption information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) via the MAGMA Indonesia application, the height of the ash plume was observed to be around 900 meters above the peak or 4,576 meters above sea level.

The ash plume was observed to be white to gray with moderate intensity towards the southwest. The eruption of Mount Semeru was still ongoing when this report was made.

(Read: Countries with the Most Active Volcanoes in the World, Indonesia Ranks First)

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 00:00-06:00 WIB showed 41 eruption earthquakes with amplitudes of 10-22 millimeters and durations of 62-180 seconds.

Subsequently, there were 2 avalanche earthquakes with amplitudes of 8-10 mm and durations of 44-79 seconds, and 2 emission earthquakes with amplitudes of 6-8 millimeters and durations of 62-65 seconds.

PVMBG advises against any activities 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 (river borders) 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 7,255 volcano eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,981 occurrences.

(Read: Trends in Volcanic Eruptions in Recent Years)