Mount Semeru in East Java erupted again on Saturday (13/12/2025) at 06:28 AM WIB. In the last week, Mount Semeru has erupted 36 times. Based on 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 500 meters above the peak (4,176 meters above sea level). The ash column was observed to be white to grey with moderate intensity towards the north. Mount Semeru's eruption was still ongoing when this report was made. According to the MAGMA Indonesia volcano activity report, Mount Semeru's activity level is at Level III (Alert). Seismic observations on December 13, 2025, from 00:00-06:00 AM WIB, showed 45 eruption tremors with amplitudes of 10-22 millimeters and durations of 84-160 seconds. Additionally, there were 5 avalanche tremors with amplitudes of 2-6 mm and durations of 52-87 seconds, and 7 exhalation tremors with amplitudes of 3-6 millimeters and durations of 34-69 seconds. PVMBG advises against any activities in the southeast sector along Besuk Kobokan, as far as 13 kilometers from the peak (eruption center). Beyond this distance, the public should not engage in activities within 500 meters of the riverbanks (river borders) along Besuk Kobokan due to the potential for expansion of hot clouds and lava flows up to 17 kilometers from the peak. Throughout 2025, MAGMA Indonesia has recorded 7,320 volcanic eruptions across Indonesia. Mount Semeru in East Java had the most eruptions with 3,014 times.