Warning! Mount Semeru Erupts Again This Morning (Tuesday, December 9, 2025)

Mount Semeru in East Java erupted again on Tuesday (December 9, 2025) at 08:18 AM Western Indonesian Time (WIB). In the last week, Mount Semeru has erupted 11 times.

According to eruption information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) via the MAGMA Indonesia application, the height of the ash column observed was approximately 600 meters above the peak (4,276 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 120 seconds.

(Read: Volcanic Eruption Trends in Recent Years)

According to MAGMA Indonesia's volcano activity report, Mount Semeru's activity level is at Level III (Alert). Seismic observations on December 9, 2025, from 00:00-06:00 WIB showed 46 eruption/explosion earthquakes with amplitudes of 10-22 millimeters and earthquake durations of 114-200 seconds.

Subsequently, 2 rockfall earthquakes occurred with an amplitude of 2 mm and durations of 54-82 seconds, as well as 4 shallow gas emission earthquakes with amplitudes of 4-8 millimeters and durations of 58-87 seconds.

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

Throughout 2025, MAGMA Indonesia has recorded 7,269 volcanic eruptions across Indonesia. Mount Semeru in East Java recorded the most eruptions with 2,989 times.

(Read: Indonesia Has the Most Active Volcanoes in the World)