The study was based on the scenario of an earthquake with an intensity of up to 6-plus on the Japanese scale hitting Tokyo. The scale runs from zero to 7.
The survey assessed the risks of buildings collapsing, fires breaking out, and how difficult it would be for residents to evacuate and for responders to extinguish fires and perform rescue operations.
The survey looked at 5,177 communities and ranked their vulnerability on a 5-level scale.
85 communities had the highest risk of "Rank 5”. They were mainly in older downtown areas such as Arakawa and Adachi wards, and in neighborhoods in other wards with high concentrations of wooden houses.
The most vulnerable among Rank 5 districts was Machiya 4-chome in Arakawa Ward. This was followed by Senju-yanagicho in Adachi Ward, and Arakawa 6-chome in Arakawa Ward.
Rank 4 districts were spread over a wide area that included the eastern part of Tokyo's 23 wards as well as Ota, Shinagawa, and Edogawa.
Since the previous survey 5 years ago, risks have gone down in Taito and Sumida wards, where roads have been repaired and constructed, making evacuation and rescue easier. But risks have risen in parts of Nakano and Suginami wards where roadwork has been slow.
The Tokyo government says, "People should be aware of the risks in their neighborhood and use the data to improve disaster preparedness. The data is posted on the Tokyo Metropolitan Government website."
In Tokyo overall, the risk of buildings collapsing is down on average by 20 percent, and the risk of fire is down by 40 percent from the last survey. The drop is attributed in part to buildings being reconstructed with higher earthquake-resistance and fire-proofing.
But risks have risen in Nakano and Suginami wards, along Kannana-Dori Avenue and in parts of the Tama area. The rise is attributed to the development of new residential areas and an increase in the number of new wooden houses that can easily catch fire. Slow progress in rebuilding narrow roads that make evacuation and rescue difficult are also to blame.
In contrast, risks are down in Higashi-Ikebukuro 4-chome and 5-chome of Toshima Ward thanks to redevelopment projects by the Tokyo government and the ward. They include projects in which areas with a high concentration of wooden houses were cleared and replaced with quake-resistant residential complexes.
The Tokyo government has earmarked 129.8 billion yen, or 1.2 billion dollars in its fiscal 2018 budget bill for quakeproofing and fireproofing of areas with numerous wooden houses. Some of the money will also go to the removal of utility poles. Officials say they will work with wards and other parties to promote disaster preparedness.