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

Mount Semeru in East Java erupted again on Thursday (8/21/2025) at 11:03 PM WIB. In the last week, Mount Semeru has erupted 23 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 was observed to be around None meters above the peak (None meters above sea level).

Visual eruption was not observed. The eruption was recorded on a seismograph with a maximum amplitude of 21 millimeters and a duration of 151 seconds.

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

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

Furthermore, 2 times of rockfall tremors with amplitudes of 2-3 mm and durations of 65-75 seconds, and 14 times of exhalation tremors with amplitudes of 3-8 millimeters and durations of 32-85 seconds occurred.

PVMBG advises against any activity in the southeast sector along Besuk Kobokan, as far as 8 kilometers from the peak (eruption center). Beyond that distance, people should not conduct activities within 500 meters from the river bank (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 5,734 volcanic eruptions across Indonesia. Mount Semeru in East Java has erupted the most with 2,298 times.

(Read: Volcanic Eruption Trends in Recent Years)