The slopes of Mount Semeru are back on high alert following a series of significant volcanic activities. A total of 16 eruptions were recorded within a six-hour period on Tuesday (30/6/2026), forcing monitoring post officers to enforce access bans at several high-risk points.
Mount Semeru Monitoring Post officer, Sigit Rian Alfian, confirmed that the increased activity was recorded from 12:00 to 18:00 local time. Based on observation data, the eruption of the tallest mountain on Java Island produced ash columns ranging from 300 meters to 1.2 kilometers high. In addition, incandescent lava flows were observed sliding 1 to 1.5 kilometers toward the southeastern sector.
Given the potential threat of pyroclastic flows (hot clouds) and lahars that could reach up to 17 kilometers, relevant authorities have strictly prohibited resident activities in four river channels originating directly from the crater. The primary exclusion zone is along Besuk Kobokan up to a radius of 13 kilometers from the peak.
Furthermore, the monitoring post emphasized that Mount Semeru's current status remains at Level III (Alert/Siaga). Residents and tourists are urged to refrain from any activities within a 5-kilometer radius of the crater center to anticipate the threat of flying incandescent rocks and other secondary hazards that could occur at any time due to crater fluctuations.
