Warning! Mount Semeru Erupts Again This Morning (Monday, December 1, 2025)

Mount Semeru in East Java erupted again on Monday (1/12/2025) at 05:09 AM WIB. In the last week, Mount Semeru only erupted once.

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 500 meters above the peak (4,176 meters above sea level).

The ash column was observed to be white to grey with thick intensity towards the southwest. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 135 seconds.

(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). Seismic observations on December 1, 2025, from 6:00 PM to 11:59 PM WIB showed 25 eruption quakes with amplitudes of 12-22 millimeters and durations of 63-138 seconds.

Subsequently, there were 14 avalanche quakes with amplitudes of 2-4 mm and durations of 41-64 seconds, and 22 emission quakes with amplitudes of 2-9 millimeters and durations of 37-75 seconds.

PVMBG advises against any activity in the southeast sector along Besuk Kobokan, as far as 13 kilometers from the peak (eruption center). Beyond this distance, the public should not engage in activities within 500 meters from the riverbanks (river boundaries) along Besuk Kobokan, as there is potential for expansion of hot clouds and lava flows up to 17 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 7,122 volcano eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,880 events.

(Read: Volcanic Eruption Trends in Recent Years)