No one died in the recent earthquake that struck Tottori Prefecture, but the temblor was strong enough to cause extensive damage. Several thousand people are still in evacuation centers, which means it is not safe for them to live in their homes. Most of these houses were probably built before the latest building standards were put in place to minimize damage caused by large quakes, but what most people don't know is that these standards are not uniform throughout Japan.

Since they were first implemented in 1952, the standards have been revised twice: first in 1981, and a second time in 2000. In 1952, the government devised a map of Japan that illustrated the perceived differences in earthquake frequency and force from one region to another. The most dangerous areas were the Kanto, Chubu, Kansai and eastern Tohoku regions. Other areas, such as Shikoku and Chugoku, were considered slightly less dangerous, Kyushu even less so.

These findings are referenced by builders when designing structures. Specific areas are given a numeric rating from 0 to 1.0, with 1.0 indicating the most dangerous situation in terms of quake frequency and force. In those areas, designers must incorporate into their buildings the maximum quake-proof standards set by the government. In a region with a quake rating of 0.9, however, designers are only required to incorporate 90 percent of the maximum standard into their buildings. As the rating drops, so does the strictness of the standard.