Mudslide Traps 390 Hikers in Nagano; Temporary Bridge Allows Descent

A mudslide destroyed the sole road to Mount Tsubakuro in Japan’s Northern Alps on August 8, leaving approximately 390 hikers and lodge staff stranded in Azumino City, Nagano Prefecture. Heavy rain triggered the disaster after 78 millimeters fell in 12 hours. No injuries were reported. A temporary bridge allowed over 40 people to descend on foot by August 9 afternoon, though full repairs will take one to two weeks.

What happened on the mountain road

At 8:30 p.m. on August 8, rainfall exceeded the regulatory threshold on Nagano’s Prefectural Road Yari-ga-take Yamamura Line. Authorities closed the road to vehicles. While patrolling, officials discovered a landslide and a collapsed bridge. The bridge carried the only access route to Mount Tsubakuro’s trailhead, a 2,763-meter peak popular with hikers. The Nagano Meteorological Agency recorded 78 millimeters of rain in the 12 hours before 1:50 a.m. on August 9, driven by warm, humid air.

How 390 people became trapped

Three lodging facilities in the isolated area held 267 people as of 2 p.m. on August 9, including staff. The stranded included hikers at mountain huts near Mount Tsubakuro’s summit and guests at Nakabusa Onsen hot spring resort. A 47-year-old temple worker from Tokyo who descended via the temporary bridge said the sight of the collapsed bridge was frightening but she was grateful to reach safety. No casualties were reported among those trapped.

Temporary crossing and recovery timeline

By August 9 afternoon, officials installed a temporary bridge allowing foot traffic across the debris. More than 40 people crossed on foot and were transported by city buses to JR Hotaka Station and other destinations. Vehicles remain unable to pass. Authorities estimate one to two weeks for emergency repairs to restore vehicle access. The road closure affects the only route to the Northern Alps’ popular Tsubakuro trailhead.

Impact on tourism and mountain access

The disruption blocks access to one of Japan’s most visited alpine destinations during peak climbing season. Water supply to approximately 1,600 inns and villas in the region has been disrupted by the landslide. Hikers planning trips to Mount Tsubakuro and nearby peaks face delays until the road reopens. The prefecture and city coordinated the evacuation and temporary infrastructure to minimize stranding duration.

Final Thoughts

The mudslide and bridge collapse created a brief but serious crisis for 390 stranded hikers and lodge staff in Nagano’s Northern Alps. Swift installation of a temporary bridge on August 9 allowed evacuation, though full road recovery will take up to two weeks. Visitors should monitor road conditions before attempting trips to Mount Tsubakuro.

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