Photo/IllutrationRescue workers search for victims after a mudflow hit the area in Kumano, Hiroshima Prefecture, in July. (Asahi Shimbun file photo)

The number of prefecture-designated “caution zones” at high risk of landslides is 6.4 times the figure of 10 years ago, although getting people to evacuate such areas could remain a difficult task.

As of Sept. 30, 542,184 areas of Japan had been officially designated as caution zones following basic investigations by prefectural governments, compared with 85,190 as of March 31, 2008, according to the land ministry.

The designation is based on the law on sediment disaster countermeasures, which went into force in 2001.

If an area is designated as a caution zone, the local government is required to create evacuation plans and hazard maps.

Prefectural governments were apparently more willing to designate such zones in response to the series of disasters this year and to encourage residents in these zones to evacuate.

However, the designation does not guarantee that people will flee when danger arises.

The torrential rain that caused flooding in western Japan in July killed 119 people. Sixty-nine of the 107 victims whose places of death have been identified were within designated caution zones or the more dangerous special caution zones.

Land ministry officials asked people in the affected areas why they did not flee. Some replied, “It is safer to stay at home,” while others said, “People around us also did not evacuate.”

The number of sediment disasters in 2017 was 1,514, the highest in 10 years. But the number this year as of Nov. 30 was 3,317, more than double the figure last year.

An estimated 660,000 sites are viewed as caution or special caution zones across Japan.

The central government has asked local governments to complete their basic investigations of the sites for possible designation no later than the end of fiscal 2019.

In 23 prefectures, 100 percent of areas that were checked were designated as caution or special caution zones.

The rates were 32 percent in Chiba Prefecture and 37 percent in Ehime Prefecture.