Indonesian authorities rescued and assisted more than 170 people stranded after Mount Semeru erupted suddenly in East Java. Pyroclastic flows traveled up to 13 km (8 miles) and ash columns reached about 2 km (1.2 miles), prompting officials to raise the alert level. Nearly 1,000 residents were evacuated from nearby villages; no fatalities have been reported. Authorities warn the eruption remains active and may expand the current 8 km (5-mile) exclusion zone.
Over 170 Climbers Rescued After Sudden Eruption of Indonesia’s Mount Semeru
Indonesian authorities rescued and assisted more than 170 people stranded after Mount Semeru erupted suddenly in East Java. Pyroclastic flows traveled up to 13 km (8 miles) and ash columns reached about 2 km (1.2 miles), prompting officials to raise the alert level. Nearly 1,000 residents were evacuated from nearby villages; no fatalities have been reported. Authorities warn the eruption remains active and may expand the current 8 km (5-mile) exclusion zone.
05:01 PM, 11/20/2025Environment
Indonesian authorities assisted more than 170 climbers who were stranded after Mount Semeru erupted unexpectedly, and warned that seismic signals indicate the eruption may continue.
About 178 people — including climbers, porters, guides, tourism officials and visitors — began ascending the 3,676-meter (12,060-foot) volcano in Lumajang district, East Java, and became stranded at the Ranu Kumbolo campsite on Wednesday. Officials reported they are safe and are being helped to return.
Priatin Hadi Wijaya, head of the Center for Volcanology and Geological Disaster Mitigation, said the campsite lies outside the primary danger zone and is on the mountain’s northern slope, which was not directly in the path of the hot cloud flow. Still, those at the site may have been exposed to volcanic ash.
Mount Semeru produced scorching pyroclastic flows — mixtures of hot gas, ash and volcanic rock — that surged down the slopes in multiple pulses from midday into the evening. Scientists reported flows traveled up to 13 kilometers (8 miles) from the summit, while a dense column of hot material rose about 2 kilometers (1.2 miles) into the air.
Muhammad Wafid, chief of Indonesia’s Geology Agency, said seismic activity remains high with growing signals of avalanches and pyroclastic density currents. Authorities warned people to avoid the Besuk Kobokan River valley, which has been a visible pathway for incandescent avalanches and hot flows, and said they are considering expanding the current 8-kilometer (5-mile) exclusion zone.
Nearly 1,000 residents from three high-risk villages in Lumajang were evacuated to government shelters, according to the National Disaster Mitigation Agency. Officials reported no confirmed fatalities.
Social media footage showed dense ash clouds sweeping through plantations and forested valleys toward a river beneath a bridge. Local reports described a strong sulfur smell and said two motorcyclists crashed on a bridge after being exposed to hot ash; both were reported to have sustained severe burns.
Also known as Mahameru, Semeru has erupted frequently over the last two centuries. Its last major eruption in December 2021 killed 51 people and injured many more, burying villages in volcanic material and forcing the evacuation of more than 10,000 people. The government later relocated nearly 3,000 houses out of the formal danger zone.
Indonesia — an archipelago of more than 280 million people — sits on the Pacific "Ring of Fire," a zone of frequent earthquakes and volcanic activity. Authorities continue to monitor Semeru closely and urge the public to follow evacuation orders and avoid river valleys and other known flow paths.