Before you buy — or decide how much to spend on — a house in Japan, look at where it sits on the hazard maps. They're public, detailed and free.
Where to find them
The national hazard-map portal run by the Geospatial Information Authority of Japan (disaportal.gsi.go.jp) layers flood, landslide, tsunami and storm-surge risk over a map you can search by address. Each city also publishes its own hazard map (ハザードマップ), often with evacuation sites.
What to look at
- River flooding — the expected depth in a major flood. Over about 0.5 m reaches floors; over 3 m reaches a second storey.
- Landslide warning zones (土砂災害警戒区域) — common for houses at the foot of slopes in rural Japan.
- Tsunami and storm surge for coastal homes.
- Liquefaction on reclaimed or low-lying land.
How it changes your plans
- When buying, agents must now explain the property's position on the flood hazard map as part of the formal sales explanation — ask for it in English.
- Check that your fire insurance includes flood cover if the house is in a flood zone.
- For renovation, raise electrics and boilers above expected flood levels, and prioritise drainage and retaining walls.
Each of our location pages links the hazard map for that area, and our Buying Support includes a hazard check before you commit.
