Further, about 51% of the national land is a heavy snowfall area, which is inhabited by about 15% of the nation's total population (Figure 1-2-18). Sustaining the lives and economic activities of the people living there requires keeping them protected from avalanches and snowstorms and taking measures, such as clearing and melting the snow. In February 2014, heavy snowfalls hit Japan centering in Kanto and in Yamanashi and Nagano prefectures, dumping the deepest snowfalls in 100 years. Those heavy snowfalls caused huge damages paralyzing public traffic services and isolating many villages in the City of Kofu and elsewhere.

Japan is located in a quake-prone zone at the boundaries of four tectonic plates, where about 20% of the world's earthquakes having a magnitude of 6 or higher occur. In addition, Japan is prone to suffer from major damages from tsunami as the nation is surrounded by seas on its four sides, with the long and complex contours of its coastlines. A stage for recurring occurrences of widespread damages in history, the Nankai Trough, in particular, has hosted subduction-zone earthquakes measuring on the 8-magnitude

Populations and Areas of Heavy Snowfall Regions

Category	Nationwide	Heavy Snowfall Region
(percentage ratio to nationwide)	Special Heavy Snowfall Region
(percentage ratio to nationwide)
Population
(thousand)	128,057	19,634 (15.3)	3,209 (2.5)
Area ( $ km^{2} $ )	377,950	191,798 (50.7)	74,898 (19.8)
Number of municipalities	1,720	532 (30.9)	201 (11.7)

(Notes) 1 The number of municipalities (special wards counted as one each) as of April 1, 2012. Populations are based on the 2010 National Census (as of October 1, 2010). 2 Areas are based on “Nationwide Prefectural and Municipal Area Survey” by Geospatial Information Authority of Japan (as of October 1, 2010). Source) MLIT

order, each 150 years apart, since about 100 years ago. An increasingly impending risk of the occurrence of earthquakes in this region has been suggested in consideration of the frequencies with which quakes have occurred there in the past (Figure 1-2-19). Subduction-zone earthquakes measuring on the 8-magnitude order, equivalent to the Great Kanto Earthquake that occurred in 1923, are thought to hit the Tokyo metropolitan area every 200 to 400 years apart. Though the next occurrence is forecast to come 100 to 300 years ahead, it is forecast to be preceded with several occurrences of epicentral earthquakes on the 7-magnitude order occurring underneath the Tokyo metropolitan area (Figure 1-2-20).

Figure 1-2-19

Distributions of Largest Seismic Intensities Assumed from a Nankai Trough

Huge Earthquake

Source) Report by the Nankai Trough Megaquake Preparedness Review Working Group, Disaster Preparedness Measures Promotion Review Meeting, Central Disaster Management Council, Cabinet Office.

Distributions of Seismic Intensity Assumed from an Epicentral Earthquake Occurring underneath the Tokyo Metropolitan Area (downtown south)

Source) Report by the Tokyo Metropolitan Area Epicentral Earthquake Preparedness Review Working Group, Central Disaster Management Council, Cabinet Office.

## (2) Vulnerabilities brought by climate changes and urban modernization

The Working Group I Report (Physical Science Basis) of the United Nations Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report released in September 2013 says, “Warming of the climate system is unequivocal,” and proceeds to predict, “ Extreme precipitation events over most of the mid-latitude land masses and over wet tropical