Mount Semeru, located on the border of Lumajang and Malang regencies, East Java, showed significant volcanic activity again on Monday (6/7/2026). The eruption, which occurred at 05:13 WIB, produced an ash column approximately 1,000 meters above the peak, reaching 4,676 meters above sea level (masl).
According to the report from Yadi Yuliandi, an officer at the Mount Semeru Observation Post, the observed ash column was gray, thick, and leaning towards the north. Seismograph recordings showed the eruption had a maximum amplitude of 22 mm and lasted for 167 seconds. Currently, the status of the tallest volcano on Java Island remains at Level III (Alert).
The Center for Volcanology and Geological Hazard Mitigation (PVMBG) emphasized a strict ban on public activities within a five-kilometer radius from the crater. In addition, residents are prohibited from approaching areas along Besuk Kobokan within 13 kilometers of the peak to avoid the threats of volcanic rock ejecta, hot clouds, and lahar flows.
The Lumajang Regency Government is paying special attention to sand miners operating around the river flows. Lumajang Regent, Indah Amperawati, reminded that the threat comes not only during the eruption but also from volcanic material deposits that still retain high temperatures. Piles of this material risk triggering secondary explosions that could endanger lives.
Furthermore, the government urges residents to always be vigilant about weather changes on the mountain slopes. High rainfall in the peak area has the potential to trigger the movement of leftover eruptive material deposits, making the lahar flow path a highly vulnerable zone. The public is advised not to focus solely on eruption updates, but also to understand the latent risks of volcanic materials along the river channels.
