Mount Semeru Erupts on Wednesday Afternoon, Activity Level at Alert

Mount Semeru in East Java erupted again on Wednesday (10/12/2025) at 02:37 PM WIB. In the last week, Mount Semeru has erupted 18 times.

Citing eruption information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) via the MAGMA Indonesia application, the height of the observed ash column reached None meters above the peak (None meters above sea level).

The visual eruption was not observed. Mount Semeru's eruption 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). Seismic observations on December 10, 2025, from 06:00 AM-12:00 PM WIB showed 42 eruption tremors with amplitudes of 10-22 millimeters and a duration of 64-128 seconds. Additionally, there were 4 emission tremors with amplitudes of 6-8 millimeters and a duration of 33-86 seconds.

PVMBG advises against any activity 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 it has the potential to be affected by the expansion of hot clouds and lava flows up to 17 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 7,283 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,996 events.

(Read: Volcanic Eruption Trends in Recent Years)