Warning! Mount Semeru Erupts Again Tonight (Friday, December 19, 2025)

Mount Semeru in East Java erupted again on Friday (12/19/2025) at 00.29 WIB. In the last week, Mount Semeru has erupted 26 times.

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 300 meters above the peak (3,976 meters above sea level).

The ash column was observed to be white to gray with moderate intensity towards the south. 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 volcanic activity report, Mount Semeru's activity level is at Level III (Alert). Seismicity observations on December 19, 2025, from 18:00-23:59 WIB showed 38 eruption tremors with amplitudes of 12-22 millimeters and durations of 72-135 seconds.

Furthermore, there were 3 avalanche tremors with amplitudes of 1.5-2 mm and durations of 39-73 seconds, and 7 exhalation tremors with amplitudes of 2-7 millimeters and durations of 29-64 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 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 7,395 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 3,050 recorded.

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