SHIZUOKA - Mount Fuji has entered its summer climbing season, drawing hundreds of thousands of visitors while authorities on its Shizuoka and Yamanashi sides take sharply different approaches to protecting climbers from a possible eruption.
All three climbing routes on the Shizuoka side opened in July, and more than 200,000 people are expected to attempt to reach the summit this season if visitor numbers follow their usual pattern.
More than 300 years have passed since Mount Fuji last erupted, and experts have repeatedly warned that another eruption could occur at any time.
An eruption could send large volcanic rocks flying near the crater and expose climbers to pyroclastic flows, lava and other life-threatening hazards.
Even under normal conditions, it takes at least about three hours to walk from the summit to the fifth station, making a rapid and orderly descent difficult during an emergency.
Yamanashi Prefecture installed an emergency shelter on the Yoshida Trail in 2026 to provide climbers with temporary protection during an eruption.
The reinforced-concrete structure measures 2.5 meters wide and 5.4 meters deep and can accommodate about 135 people. Yamanashi plans to install 13 shelters along the Yoshida Trail over the next five years.
Shizuoka Prefecture, however, says it has no plans to install shelters on its side of the mountain.
"The time spent remaining in a shelter could itself become dangerous," said Norihisa Ashikawa, head of the Shizuoka Prefectural Government's crisis information division. "The basic principle of disaster prevention is to have people leave Mount Fuji as quickly as possible."
The national government, local authorities and other organizations have installed eruption-monitoring equipment at more than 40 locations around Mount Fuji.
On the three Shizuoka climbing routes, the Japan Meteorological Agency issues information explaining volcanic conditions when abnormal activity is detected. Instructions to descend are then delivered through mountain huts and smartphone applications used by individual climbers.
"There are three climbing trails, so providing shelters for everyone using them would be somewhat unrealistic," Ashikawa said.
Mountain huts responsible for guiding climbers to safety are also preparing for an emergency, though workers remain concerned about whether instructions could reach everyone in time.
At Unkaiso, a mountain hut at the sixth station of the Fujinomiya Trail, staff have prepared helmets and loudspeakers for use during an eruption.
"We would call out, 'An evacuation order has been issued, so please descend quickly,'" said Naotoshi Watanabe, the hut's representative.
Watanabe said Mount Fuji's vast size would make it difficult to distribute emergency information across the entire area. "Mount Fuji is enormous. I think it would be difficult to make sure the information truly reaches people over such a wide area," he said.
The danger was demonstrated by the 2014 eruption of Mount Ontake, which straddles Nagano and Gifu prefectures. The eruption killed 58 people, mostly climbers, and left five others missing.
Experts believe Mount Fuji is unlikely to produce a major eruption without any warning, but they caution that it is impossible to know in advance when signs of an eruption will appear.
"If large numbers of people are using a climbing route, the standard approach would be to provide some kind of facility where they can take emergency refuge," said Takayoshi Iwata, a visiting professor at Shizuoka University's Center for Integrated Research and Education of Natural Hazards.
Mount Fuji can become heavily congested around sunrise and during bad weather, complicating any attempt to move climbers quickly down the mountain.
Authorities and other organizations involved in managing Mount Fuji will need to strengthen measures, including consideration of additional shelters, to protect climbers if signs of an eruption emerge.
The Hoei eruption, Mount Fuji's most recent and one of its largest recorded explosive eruptions, began on December 16, 1707, from vents that opened on the mountain's southeastern flank rather than at the summit, and continued intermittently until January 1, 1708. The eruption created the Hoei craters and Mount Hoei, which remain prominent features on the Shizuoka side.
The eruption ejected vast quantities of pumice, scoria and volcanic ash over surrounding communities. Heavy deposits buried farmland and damaged villages near the mountain, while ash was carried eastward as far as Edo, present-day Tokyo, roughly 100 kilometers away. The accumulated material also contributed to flooding and sediment disasters that continued after the eruption ended.
The event occurred 49 days after the powerful Hoei earthquake struck central and southwestern Japan. Researchers have examined whether the earthquake influenced volcanic activity beneath Mount Fuji, although the precise relationship remains uncertain. No eruption has occurred at Mount Fuji since the Hoei event, but the mountain remains an active volcano under continuous observation.
Source: SBSnews6
