Photo/IllutrationThe Asahi Shimbun

Eastern Tokyo is still at the greatest risk of major earthquake damage in the metropolitan area, with building collapses and fires more likely, but the overall risk has declined, according to the Tokyo metropolitan government.

The authority released an updated hazard map on Feb. 15, the first since 2013.

The map charts risk levels combining fire and building collapses on a five-point scale in the event of a major earthquake.

Tokyo’s eastern neighborhoods are still at an elevated level of risk due to their numerous wooden houses and narrow roads.

The updated map shows the risk level for building collapses decreased about 20 percent on average while the risk of fire dropped about 40 percent across the entire Tokyo metropolitan area as a result of redevelopment in densely populated residential areas with widened roads, quake-resistant houses and other positive factors.

The survey to create the quake hazard map has been conducted once every five years since 1975, in principle.

The metropolitan government divided the capital’s 23 wards and western cities into 5,177 areas along community borders and evaluated potential damage including building collapses and fires from an earthquake with a maximum seismic intensity of upper 6 on the Japanese scale of 7.

The risk levels were analyzed based on ground stability, building structure, building density, width of roads, and the number of oil stoves owned by households in the areas.

The map shows that of the 85 areas at risk Level 5, half are in Arakawa, Adachi and Sumida wards on the eastern side of Tokyo’s 23 wards.

A total of 287 areas are at Level 4, which outside the eastern neighborhoods of the capital’s 23 wards include Ota Ward and Nakano Ward. In some of those areas, the level of risk increased due to higher population densities caused by the construction of new homes.

The map is available in Japanese at (http://www.toshiseibi.metro.tokyo.jp/bosai/chousa_6/home.htm).