We gather data objectively from the latest available sources and share what we find useful.
We hope it helps anyone looking for a home in Japan, or considering a business built around property.
Much of Japan appears somewhere on a hazard map, and earthquakes are part of life anywhere in the country. Most buyers do not try to avoid every coloured area. They check what the map shows for the address, then choose a building and insurance that handle that risk well.
A hazard map should not tell you whether to buy a property. It should tell you what to check next.
Where to Look
- Hazard Map Portal Site. Enter the address in the national Kasaneru Hazard Map to see modelled flood depth, landslide zones and tsunami areas on one map. Turn the layers on one at a time.
- The municipality's hazard map. Wards and cities publish more detailed flood and evacuation maps, often in English.
- Historical maps. Konjaku Map on the Web places old maps beside modern ones, showing former rivers, wetlands or reclaimed land.
When you buy, the broker's explanation of important matters must also show where the property sits on the municipal flood hazard map and whether it is in a designated landslide warning zone.
How to Read the Result
| Risk | What the map shows | What buyers usually look for |
|---|---|---|
| Earthquake | Applies everywhere in Japan. | A building approved under the post-1981 standard, a seismic grade where available, and earthquake insurance. |
| River and inland flooding | Modelled water depth after severe rainfall. | A floor above the modelled depth; in condominiums, where the electrical equipment and parking sit; flood cover. |
| Liquefaction | Reclaimed land, former waterways and low ground. | Foundations on piles down to firm ground, which is usual for larger condominiums, and the history of the land. |
| Landslide | Yellow warning zones and red special warning zones on slopes. | Red zones are generally avoided. In yellow zones, a careful look at the slope and retaining walls. |
Building is strictly regulated: housing developments need the governor's permission, and new homes with living rooms must be built to withstand debris.
Most buyers simply do not buy here.
No building restrictions, but the zone calls for real care.
Look at the slope, the retaining walls and the evacuation route before committing.
Building Standard and Seismic Grade
Buildings approved on or after 1 June 1981 meet Japan's “new seismic standard”, and most buyers of Tokyo condominiums look for this first. Buildings approved before then follow the older standard, but many have since had a seismic assessment or retrofit that brings them up to the current level, so it is worth asking. Rules for wooden houses were strengthened again in June 2000.
Structure matters as much as age. After the 2016 Kumamoto earthquakes, a government survey of the worst-hit area found:
Across all ages, the difference between structures was just as clear:
Older RC buildings therefore have a far stronger record than older wooden ones, although the government still encourages retrofitting pre-1981 RC buildings.
Some buildings also carry a seismic grade under the Housing Performance Indication System. Grade 1 is the Building Standards Act level: a building that will not collapse in the kind of earthquake expected once in several hundred years, around seismic intensity 6 upper to 7 in Tokyo, the shaking seen in Tokyo in 1923 and in Kobe in 1995.
In Kumamoto, grade 3 wooden houses showed no major damage. Seismic isolation and damping structures, common in newer towers, reduce shaking further.
Insurance
Flood cover
An option within fire insurance. It typically pays when any one of these applies:
Some insurers offer riders for damage below these thresholds, for example to water heaters and other equipment; where flood risk is high, they are worth adding. Following a 2023 revision of reference rates, flood premiums can vary by municipality according to flood risk.
Earthquake insurance
Added to a fire insurance policy and backed by the government.
Premiums are discounted for seismic isolation (50%), seismic grade (10–50%) and buildings from June 1981 onwards (10%).
In a condominium, the management association insures the common parts of the building; each owner insures their own unit and contents.
What to Do, Risk by Risk
Choose a building from June 1981 onwards, or an older one that has been assessed or retrofitted. Prefer RC to older wooden structures, check the seismic grade and repair records, and add earthquake insurance.
Compare the modelled depth with the floor you are buying. In a condominium, upper floors and above-ground electrical rooms help. Add flood cover, and riders where the risk is high.
Check the foundation and the history of the land. For a house, commission a ground survey before buying.
Do not buy in a red zone. In a yellow zone, take particular care with the slope, retaining walls and evacuation route.
Many established and valuable parts of Greater Tokyo have some natural-hazard exposure. Checked this way, it becomes one more factor in choosing a property rather than a reason to avoid an area.
Frequently Asked Questions
How do I check flood and earthquake risk for a property in Japan?
Enter the address in the national Kasaneru Hazard Map on the Hazard Map Portal Site to see modelled flood depth, landslide zones and tsunami areas, turning layers on one at a time. Then check the municipality's more detailed hazard map, often in English, and historical maps such as Konjaku Map on the Web for former rivers, wetlands or reclaimed land.
Are older buildings in Japan safe in an earthquake?
Buildings approved on or after 1 June 1981 meet Japan's new seismic standard, and rules for wooden houses were strengthened again in June 2000. After the 2016 Kumamoto earthquakes, 28.2% of wooden buildings from before June 1981 collapsed in the worst-hit area, against 2.2% from June 2000. Reinforced concrete buildings of all ages had a 3.8% collapse rate, none built to the 1981 standard.
What does seismic grade 3 mean for a house or apartment in Japan?
Under the Housing Performance Indication System, Grade 1 is the Building Standards Act level: a building that will not collapse at around seismic intensity 6 upper to 7 in Tokyo, the shaking seen in Tokyo in 1923 and in Kobe in 1995. Grade 2 withstands 1.25 times that force and Grade 3 withstands 1.5 times. In Kumamoto, grade 3 wooden houses showed no major damage.
How does earthquake insurance work in Japan and how much does it cover?
Earthquake insurance is added to a fire insurance policy and backed by the government. It covers 30–50% of the fire insurance amount, up to JPY 50M for a building and JPY 10M for contents. Premiums are discounted for seismic isolation (50%), seismic grade (10–50%) and buildings from June 1981 onwards (10%).
Should I buy property in a landslide warning zone in Japan?
Red special warning zones are strictly regulated, and most buyers simply do not buy there. Yellow warning zones have no building restrictions but call for real care: look at the slope, the retaining walls and the evacuation route before committing. When you buy, the broker's explanation of important matters must show whether the property is in a designated landslide warning zone.
Sources
MLIT / Geospatial Information Authority of Japan — the official Kasaneru (Overlay) Hazard Map and Wagamachi Hazard Map.
Kenji Tani, Saitama University — historical topographic maps placed beside modern mapping.
Ministry of Land, Infrastructure, Transport and Tourism — the disclosure requirement introduced in 2020.
Collapse rates by structure and construction period in the worst-hit area.
What seismic grades 1, 2 and 3 mean under the Housing Performance Indication System.
Development permission and structural rules in red zones.
How earthquake insurance works: attachment to fire insurance, coverage limits and premium discounts.
Including the 2023 differentiation of flood rates. Flood-cover payment conditions (30%, above floor level, 45cm) are those of a standard household policy, such as Mitsui Sumitomo Insurance's.
General information only, not legal, tax or investment advice.