Over 170 Climbers Rescued After Sudden Eruption of Indonesia’s Mount Semeru

Indonesian authorities have safely evacuated more than 170 climbers who were stranded when Mount Semeru erupted unexpectedly on Wednesday, sending billowing clouds of hot ash and pyroclastic flows down the slopes of Java’s highest volcano.

Officials said about 178 people — including climbers, guides, porters, tourists, and tourism officers — had set out earlier in the day toward the 3,676-meter (12,060-foot) summit in East Java’s Lumajang district. They became trapped at the Ranu Kumbolo camping site after seismic activity intensified.

“They are safe and now being helped to return,” said Priatin Hadi Wijaya, head of the Center for Volcanology and Geological Disaster Mitigation, during a video briefing.

His colleague, Hetty Triastuty, noted that Ranu Kumbolo lies outside the main 8-kilometer danger zone. Although the site is on the northern slope — away from the path of the hot clouds moving south-southeast — climbers may still have been exposed to volcanic ash.

Mount Semeru unleashed a series of powerful pyroclastic flows and incandescent avalanches from midday to dusk Wednesday. The searing clouds traveled up to 13 kilometers (8 miles), while a dense column of ash rose 2 kilometers (1.2 miles) into the sky. In response, scientists raised the alert status to its highest level, said Indonesia’s Geology Agency chief, Muhammad Wafid.

“Semeru’s seismic activity shows the eruption remains intense, with increasing signals of avalanches,” Wafid warned. He urged residents to avoid the Besuk Kobokan River valley — the main channel for lava and searing gas — and said authorities are considering expanding the danger zone beyond the current 8 kilometers.

Nearly 1,000 residents from three high-risk villages in Lumajang have been moved to temporary shelters, according to National Disaster Mitigation Agency spokesperson Abdul Muhari. No deaths have been reported.

Videos shared online showed thick ash rolling across plantations and forested areas, engulfing a valley below a bridge. Local reports said several villages were blanketed in heavy ash, darkening the sky. Two motorcyclists reportedly suffered severe burns after crashing on a bridge covered in hot ash.

Mount Semeru, also known as Mahameru, is among Indonesia’s most active volcanoes and has erupted repeatedly over the past two centuries. Its last major eruption in December 2021 killed 51 people, injuring hundreds more and forcing the evacuation of over 10,000 residents.

Indonesia sits along the Pacific “Ring of Fire,” making it one of the world’s most disaster-prone regions for earthquakes and volcanic eruptions.