Warning! Mount Semeru Erupts Again This Morning (Thursday, August 21, 2025)

Mount Semeru in East Java erupted again on Thursday (August 21, 2025) at 05:31 AM WIB. In the last week, Mount Semeru has erupted 19 times.

Based on 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 800 meters above the peak or 4,476 meters above sea level.

The ash column was observed to be white to gray with moderate intensity towards the southwest. The eruption of Mount Semeru was still ongoing when this report was made.

(Read: Indication of Forest and Land Fire Area in West Kalimantan Province 2016-2025)

According to the MAGMA Indonesia volcano activity report, the activity level of Mount Semeru is at Level II (Alert). Seismic observations on August 21, 2025, from 00:00-23:59 WIB showed 42 eruption tremors/earthquakes with amplitudes of 10-22 millimeters and a tremor duration of 58-146 seconds.

Subsequently, there were 2 avalanche earthquakes/tremors with amplitudes of 2-3 mm and durations of 65-75 seconds, and 14 exhalation earthquakes/tremors with amplitudes of 3-8 millimeters and durations of 32-85 seconds.

PVMBG advises against any activities in the southeast sector along Besuk Kobokan, as far as 8 kilometers from the peak (eruption center). Beyond that distance, the public is advised not to conduct activities within 500 meters from the riverbank (river border) along Besuk Kobokan, as there is a potential for expansion of hot clouds and lava flows up to 13 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 5,716 volcanic eruptions across Indonesia. Mount Semeru in East Java has erupted the most, with 2,294 eruptions.

(Read: Indication of Forest and Land Fire Area in East Kalimantan until June 2025)