Warning! Mount Semeru Erupts Again This Morning (Friday, December 5, 2025)

Mount Semeru in East Java erupted again on Friday (12/5/2025) at 05.13 AM WIB. In the last week, Mount Semeru has erupted 65 times.

Based on eruption information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) through the MAGMA Indonesia application, the observed ash column reached 1,000 meters above the peak or 4,676 meters above sea level.

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

(Read: Air Quality in Indonesian Major Cities is Poor, Far from WHO Standards)

According to MAGMA Indonesia's volcanic activity report, Mount Semeru's activity level is at Level III (Alert). Seismic observations on December 5, 2025, from 18.00-23.59 WIB showed 27 eruption tremors/earthquakes with amplitudes of 10-22 millimeters and earthquake durations of 92-176 seconds.

Then, 7 avalanche tremors with amplitudes of 2-13 mm and earthquake durations of 41-234 seconds, and 9 exhalation tremors with amplitudes of 2-7 millimeters and earthquake durations of 44-95 seconds occurred.

PVMBG urges people not to carry out 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 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 7,205 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions with 2,944 times.

(Read: Not Jakarta, These are the Areas with the Worst Air Quality in Indonesia (Wednesday, June 7, 2023))