Mount Semeru, located in East Java, has once again shown volcanic activity on Sunday (12/7/2026). According to a report from the Volcano Observation Post, the eruption occurred at precisely 16:39 WIB, spewing an ash column 800 meters above the summit, or approximately 4,476 meters above sea level.
Observation officer Sigit Rian Alfian, in an official statement on the Magma ESDM website, explained that the ash column appeared white to gray with thick intensity. The ash spread was observed moving toward the north and northeast. The eruption was recorded on a seismograph with a maximum amplitude of 22 millimeters and lasted for 130 seconds.
In response to this situation, authorities issued strict recommendations for residents living around the mountain slopes. Residents are strictly prohibited from conducting any activities in the southeastern sector along Besuk Kobokan, within a 13-kilometer radius from the eruption center. Furthermore, the public is advised to maintain a safe distance of at least 500 meters from the riverbanks along the flow path to anticipate the threat of expanding pyroclastic flows and lahars, which could potentially reach a distance of 17 kilometers.
Furthermore, authorities established a safe radius of five kilometers from the peak of Mount Semeru due to the risk of incandescent rock ejection. Residents were also reminded to remain vigilant regarding potential lava avalanches and lahar flows along rivers originating from the summit, particularly Besuk Bang, Besuk Kembar, Besuk Sat, and all tributaries of Besuk Kobokan.
