Mount Semeru in East Java erupted on Sunday, August 9, 2026, at 17:00 Western Indonesia Time (WIB), according to data from the Center for Volcanology and Geological Hazard Mitigation (PVMBG) via the MAGMA Indonesia application. The latest activity brings the volcano’s total eruption count for the past week to 61 events, maintaining its status at Level III, or Alert.
Seismic Activity and Eruption Metrics
During the observation period from 06:00 to 12:00 WIB on August 9, 2026, seismic monitoring recorded 32 eruption earthquakes with amplitudes ranging from 10 to 22 mm and durations lasting between 59 and 147 seconds, as reported by PVMBG. Instrumental data also captured two collapse earthquakes with amplitudes of 3 to 4 mm and durations between 45 and 76 seconds, alongside six emission earthquakes measuring 3 to 6 mm in amplitude with durations of 31 to 39 seconds. Visual confirmation of the afternoon eruption was hindered because the visual was not observed directly, though the event registered strongly on seismographs with a maximum amplitude of 22 mm and a duration of 104 seconds.
Exclusion Zones and Public Safety Measures
Authorities have enforced strict exclusion zones around the volcano due to ongoing hazards. According to PVMBG directives, all activities are prohibited in the southeast sector along Besuk Kobokan, spanning up to 13 kilometers from the peak. Outside this immediate sector, individuals must remain at least 500 meters away from the banks of the Besuk Kobokan river. Regulatory warnings indicate that potential hot clouds and lahar flows generated by the volcanic activity could reach distances of up to 17 kilometers from the summit.
Broader Volcanic Context in Indonesia
The activity at Mount Semeru contributes to a highly active year across the archipelago. MAGMA Indonesia data shows that 3,841 volcanic eruptions have been recorded nationwide throughout 2026. Among all active Indonesian volcanoes, East Java’s Mount Semeru accounts for the highest frequency, registering 1,573 individual eruption events during the year.