Signs of volcanic activity prompted the Hakone town government to close off hiking trails around the popular tourist destination of Mount Hakoneyama southwest of Tokyo in the middle of the Golden Week holidays.
The routes were put off-limits at 5 a.m. on May 4. The Japan Meteorological Agency dispatched a group of experts to observe volcanic activity on the mountain on the same day.
The agency believes there is no immediate threat of eruption on the mountain, which straddles Kanagawa and Shizuoka prefectures, and maintained a standard Level 1 alert for the mountain on May 3.
But the agency is warning climbers to comply with the town government’s instructions and avoid restricted areas because scalding water vapor could spew from the ground without warning.
According to the agency, nine volcanic earthquakes occurred around the Owakudani area of the mountain between April 1 and 25.
Tremors increased in frequency on April 26, with 16 recorded after 2 p.m. that day. Thirty-seven earthquakes were recorded on May 2, and 35 more struck by 3 p.m. the following day.
Observations using a clinometer revealed slight signs of bulging on the mountain slopes.
The Hakone area in Kanagawa Prefecture is famous for its hot springs and natural scenery, including views of Mount Fuji.