Mount Semeru, located on the border of Lumajang and Malang regencies in East Java, recorded a significant increase in volcanic activity on Sunday (28/6/2026). In just a six-hour period, Java's highest volcano experienced four consecutive eruptions.
Mukdas Sofian, an officer at the Mount Semeru Observation Post, reported that the largest eruption occurred at 11:37 a.m. WIB, with an ash column observed reaching a height of 1,000 meters above the summit, or 4,676 meters above sea level. The dense ash column was observed spreading toward the southeast and south.
Seismograph records showed that the series of eruptions began at 05:35 a.m. WIB, followed by eruptions at 06:32 a.m., 09:11 a.m., and culminating at 11:37 a.m. WIB. Tremor intensity recorded a maximum amplitude of 22 millimeters with varying eruption durations.
Currently, Mount Semeru's alert status remains at Level III (Alert). Authorities strongly emphasize a strict ban on any activity within a five-kilometer radius of the summit crater to avoid the risk of incandescent rock ejection.
Additionally, the public is advised to stay clear of the southeastern sector along Besuk Kobokan up to 13 kilometers from the eruption center. Residents are also urged to remain vigilant against potential pyroclastic flows, lava avalanches, and cold lahar floods that could sweep through river basins originating from Mount Semeru's summit.
