Gunung Semeru erupts to 1,000 m, authorities issue safety warnings in East Java

On 25 May 2026 at 07:09 WIB, Gunung Semeru in East Java erupted, sending an ash column about 1,000 metres high (approximately 4,676 m above sea level). The eruption was recorded on a seismogram with a maximum amplitude of 19 mm and lasted roughly 2 minutes 10 seconds.

The Indonesian Center for Volcanology and Geological Disaster Mitigation (PVMBG) raised the volcano to Alert Level III (Siaga) and advised residents to avoid all activities within a 13‑kilometre southeast sector along the Besut Kobokan valley. People should also stay at least 500 metres away from riverbanks in that area, as hot ash clouds and lahars could travel up to 17 kilometres from the summit. Additionally, a 5‑kilometre radius around the crater is off‑limits due to the risk of hot rock fragments, lava falls, and sudden ash clouds. Authorities warned of potential hot clouds, lava drops, and lahar flows along the Besut Kobokan, Besut Bang, Besut Kembar, Besut Sat valleys and their tributary streams.