Japan's government has updated its assessment of the country's earthquake risk, with one densely-populated western region now facing as much as a 60 per cent chance of a major quake within the next 30 years.
Active faults in and around the Kinki region, which includes Osaka, Kyoto and Kobe, could trigger an earthquake of magnitude 6.8 or larger, with a 50 to 60 per cent probability over that period, Japan's Earthquake Research Committee said on Friday.
The probability stood at 30 per cent for active faults in the region's northwestern part, 40 to 60 per cent for those in the central area known as the Kinki triangle, and 7 per cent for the Kii Peninsula. The assessment is based on 45 active faults in and around the region.
The Kinki region has an unusually high concentration of active faults, largely because of the expansion of the Sea of Japan during the formation of the Japanese archipelago. The committee said the region's earthquake risk is now comparable to that of the Kanto region, which includes Tokyo.
The updated figures are part of a wider, ongoing review. The committee has already published long-term assessments for 114 major active faults across Japan, covering the Kyushu, Kanto, Chugoku and Shikoku regions, with assessments for the Chubu, Tohoku and Hokkaido regions still to come.
Kobe, in the Kinki region, was devastated by the magnitude-7.3 Great Hanshin earthquake in January 1995, which killed more than 6,000 people and remains one of Japan's worst recorded disasters.
This latest update comes against the backdrop of a far larger, long-feared threat facing Japan as a whole – a megaquake along the Nankai Trough, an 800-kilometre undersea trench running along the country's Pacific coast.
Last year, Japan’s earthquake investigation panel had increased the probability of that megaquake happening, rating it as 80 per cent probable within the next 30 years.
A megaquake is an earthquake of magnitude 8 or higher, capable of causing more damage than a typical quake, especially when it occurs close to the surface or in densely populated regions.
Megaquakes have struck along the trough roughly once every 100 to 150 years, with the last occurring in 1946. In a worst-case scenario, the government has estimated a Nankai Trough megaquake and the tsunami it would trigger could kill up to 298,000 people and cause economic losses of around 292 trillion yen (£1.3trn).
Japan, one of the most earthquake-prone countries in the world, has heavily invested in early warning systems and infrastructure upgrades, but officials say more preparation is needed to protect communities from a disaster of this scale.
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