Mount Semeru, located on the border of Lumajang and Malang Regencies, East Java, has once again shown significant volcanic activity. On Monday morning (7/6/2026), the highest volcano on Java Island spewed an ash column reaching a height of 1,000 meters above the peak, or equivalent to 4,676 meters above sea level.
According to a report from the Mount Semeru Observation Post, the eruption occurred at 05:13 WIB. The observed ash column was gray with thick intensity, moving toward the north. Seismograph records showed a maximum amplitude of 22 mm with an eruption duration of 167 seconds.
Currently, Mount Semeru's alert status remains at Level III (Alert). The Center for Volcanology and Geological Hazard Mitigation (PVMBG) reiterated the prohibition against public activity within a five-kilometer radius of the crater. In addition, residents are prohibited from approaching a 13-kilometer zone in the southeastern sector along Besuk Kobokan, as well as a 500-meter radius along the banks of rivers originating from the mountain peak.
The Lumajang Regency Government paid special attention to sand miners around the river channels. Lumajang Regent, Indah Amperawati, warned that volcanic material deposits left over from the eruption often retain extreme heat. This material risks triggering secondary explosions that endanger anyone nearby.
Furthermore, the threat level can increase dramatically when it rains in the peak area. Rainwater has the potential to displace hot volcanic material deposits along river flows such as Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat. The public is urged not to take seemingly stationary material deposits lightly and to remain vigilant against the dangers of cold lahar flows.
