Warning! Mount Semeru Erupts Again This Morning (Thursday, September 4, 2025)

Mount Semeru in East Java erupted again on Thursday (4/9/2025) at 09:28 AM WIB. In the last week, Mount Semeru has erupted 17 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 500 meters above the peak (4,176 meters above sea level).

The ash column was observed to be white to grey with thick intensity towards the southwest. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and a duration of 145 seconds.

(Read: West Kalimantan Produced the Most CO2 Emissions from Forest Fires Until July 2023)

According to the MAGMA Indonesia volcano activity report, Mount Semeru''s activity level is at Level II (Alert). Seismic observations on September 4, 2025, from 00:00-23:59 WIB showed 45 eruption tremors/earthquakes with amplitudes of 10-22 millimeters and durations of 50-179 seconds.

Additionally, there were 2 rockfall earthquakes with amplitudes of 6-10 mm and durations of 63-80 seconds, and 2 exhalation earthquakes with amplitudes of 8 millimeters and durations of 53-55 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, people should not engage in activities within 500 meters from the riverbanks along Besuk Kobokan due to the potential for pyroclastic flow expansion and lava flows up to 13 kilometers from the peak.

Throughout 2025, MAGMA Indonesia has recorded 5,957 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions, with 2,385 occurrences.

(Read: East Nusa Tenggara Always Hit by Forest Fires in the Last 10 Years, BMKG Urges Increased Preparedness)