Very important information to read:
This article is intended as a preliminary guide only and refers to some but not all elements required to consider in detail prior to starting any property dealings or due diligence. Property dealings are often complex, especially in foreign countries and we highly recommend you seek independent professional advice... read more... Godzilla probably won’t stomp through your neighbourhood, but Japan’s reputation for being a place struck by an unfortunate number of natural disasters is very much deserved. Earthquakes, tsunamis, floods, and typhoons pose a real threat for your property. Depending on the location of your real estate, it might be more or less at risk.
For that reason, the Tokyo Metropolitan Government has created a number of maps highlighting high-risk areas. Currently, maps for floods, liquefaction, and earthquake risk are available online. Below is a list of links and advice on how to assess risks stemming from natural disasters for properties.
Earthquake risk assessment map
Newer structures in compliance with the latest seismic building laws and standards will be more resistant to earthquakes. Older structures built under earlier, less effective standards, are likely to sustain more damage. In Japan, buildings constructed in accordance with the 1981 Amendment to the Building Standards Law are considered to meet sufficient safety standards.
Here's a map showing the earthquake risk for the Greater Tokyo area by the Bureau of Urban Development in the Tokyo Metropolitan Government. (An older version with some of Tokyo’s central areas marked on the map in English can be viewed on Property Central’s website.)
It was last updated in 2018 and assesses three types of hazards:
- Vulnerability to collapse
- Fire hazard rating
- Overall earthquake hazard rating
The vulnerability to collapse is highest for buildings that don’t meet the most recent seismic safety standards and in areas that are at risk of liquefaction (see below). In Tokyo, buildings in Taito and Sumida wards are at the greatest risk. The highest fire hazard areas are the ones most densely populated and have a high density of older, wooden buildings. Shingawa, Shinjuku and the Shitamachi (downtown areas) like Ueno and Asakusa are at highest risk for that. The overall earthquake hazard is highest in areas on or close to vault lines. Sumida, Shinjuku, Arakawa, Shinagawa and Adachi wards all received high ratings.
Liquefaction risk assessment map
Liquefaction is the process when water-saturated soil or sand loses strength and solidity during an earthquake or other sudden changes. In short, the ground starts behaving like a liquid under stress from the tremor. The effects on infrastructure and buildings can be devastating, with roads cracking open and buildings collapsing.
This map for liquefaction risk in Tokyo was last updated in 2012. An interactive version is also available. Pink areas are at highest risk, while pale yellow indicates a moderate risk, and green a low-risk area. In general, areas in lowlands are at higher risk. In Tokyo, this applies to the eastern part of the 23 wards, e.g. Adachi, Katsushika and Edogawa wards. All central wards are ranked as medium risk.
Properties at risk from typhoons
The Japanese archipelago experiences six typhoons annually on average, from around July to October or November. The storms bring torrential rainfall and heavy winds, which can be especially damaging for older, wooden buildings. In most cases, their foundations are also made of wood. Wood foundations give flexibility in the case of earthquakes, but often can’t withstand the pressure of a torrent or landslide resulting from a typhoon. About 70% of Japan is made up of mountains and hills. Homes that have a weak foundation and are built on steep slopes can literally be washed away by a heavy typhoon.
Flood risk assessment maps
With scientists warning that one consequence of climate change could be an increase in frequency and intensity of rain-related disasters, attention to the flood risk in Tokyo has increased. Parts of Tokyo lie below sea level and efforts to mitigate potential floods have been strengthened. A network of dams, dikes, reservoirs, and levees protect the Japanese capital.
Here is a list of flood hazard maps for all of Tokyo’s 23 wards and all of its outer municipalities. Some maps are combined with other hazards and some, but not all, have English translations. A quick scan with Google Translate will help you to find your ward or municipality if you don’t read Japanese. Maps for the five central wards, Shinjuku, Shibuya, Chuo, Chiyoda, and Minato can be found by clicking the respective links.
What about Mt. Fuji erupting?
The 3,776 m mountain last erupted in 1707, but it is still classified as dormant rather than extinct. The last time experts rang alarm bells for a potential eruption was in 2014, and in the end, nothing happened despite high pressure in its magma chamber. If Mt. Fuji were to erupt, the lava flow would destroy settlements and infrastructure in its vicinity but probably wouldn’t reach central Tokyo. However, the more likely scenario is that ash would rain on the capital, which would damage roads, rail, and buildings. It would take weeks for things to return to normal, and damage costs would run into trillions of yen.
By Mareike Dornhege
Similar to this:
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What happens to your home loan if your house is destroyed in a natural disaster?
Very important information to read:
This article and the above linked articles are not complete and are intended as preliminary guides only. These guides refer to some elements to consider prior to starting any property dealings or due diligence. Property dealings are often complex areas, especially in foreign countries and we highly recommend you seek independent professional advice... read more... 
