Mount Yake, Active volcano in Nagano Prefecture, Japan

Mount Yake is an active volcano of the Hida Mountains on the Nagano–Gifu border, reaching 2,455 m at its southern peak. Its two summits, the northern at 2,444 m and the southern, enclose a crater lake, and the mountain is a lava dome built of viscous andesite. A fumarole emitting sulfur sits on the western flank of the northern peak.

Mount Yake began erupting about 25,000 years ago; its last magma eruption, around 2,300 years ago, produced the Yakedake lava dome and the Nakao pyroclastic flow. Since then all eruptions have been phreatic steam explosions. In June 1915 a major blast sent a mudflow that dammed the Azusa River and formed Lake Taisho. Activity in 1907–1939 and 1962–1963 brought steam explosions and mudflows; the 1962 eruption crushed the old Yakedake Hut and injured four people.

The name Yake-dake means 'Burning Mountain', while Gifu-side residents historically called it Iwo-dake, or Sulfur Peak. The North Peak holds a fumarole emitting sulfur on its western flank, and a crater lake, Shoga-ike, lies between the two summits. The mountain is one of the 100 Famous Japanese Mountains and a constantly monitored volcano.

The northern peak is reachable via marked trails that pass active steam vents, while the southern summit remains off-limits due to unstable ground. Hikers should carry gas masks and check daily hazard warnings before attempting the ascent.

Four construction workers died from volcanic gases in 1995 while building a tunnel on the Nagano side. This event led to stricter safety protocols for all projects near active volcanic zones across the country.