Mount Semeru, located on the border of Lumajang and Malang Regencies, East Java, has once again shown an increase in volcanic activity. Throughout Tuesday (6/30/2026), the highest mountain on Java Island was recorded erupting five times within a 12-hour period.
Mount Semeru Observation Post officer, Sigit Rian Alfian, confirmed that the latest eruption occurred at 1:04 PM WIB, with an ash column reaching a height of 900 meters above the peak, or 4,576 meters above sea level. The observed ash column was white to gray in color with thick intensity, drifting toward the northeast and east sectors.
Based on seismograph data, this eruption had a maximum amplitude of 21 mm with a duration of up to 99 seconds. Throughout the observation period from 00:16 to 13:04 WIB, eruption heights ranged from 500 to 900 meters above the peak.
As of now, Mount Semeru's status remains at Level III (Alert). Authorities stressed the importance of public compliance with the exclusion zone, particularly along Besuk Kobokan up to 13 kilometers from the eruption center. In addition, residents are prohibited from conducting activities within a five-kilometer radius from the main crater to avoid the risk of incandescent rock ejection.
People living or operating around river basins originating from Semeru's peak, such as Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, are advised to heighten vigilance against the threat of pyroclastic flows and cold lava flows, especially during heavy rainfall.
