Japan House Hazard Maps: Check the Address Before You Visit

A beautiful house beside a river can still belong on your shortlist. The useful question is what the published hazard information means for that exact address, the access route and your intended use. Do this check before spending money on a viewing trip.

This is a screening workflow. It does not calculate the probability of a particular house being damaged or certify that an unshaded property is safe.

Start with the location you can actually confirm

Ask the agent for the precise address or a confirmed map pin. A town-centre marker is not enough to decide which side of a flood boundary a home occupies. Record whether the point identifies the building, the parcel or an approximate neighbourhood. If the location is withheld, leave the hazard result unresolved.

Open the official Hazard Map Portal. It brings together several hazard layers and links to municipal maps. Use the national view to orient yourself, then consult the municipality's own map and its notes. Data coverage and update dates matter.

Check each hazard separately

Work through flood, inland flooding where available, landslide, tsunami and storm-surge information relevant to the location. A river flood layer cannot answer a question about slope failure. Read the legend and scenario before writing down a result; identical colours on different maps need not mean the same thing.

Save the map name, issuing authority, version or publication date, viewing date and the legend alongside the address. The portal's FAQ explains scenario differences and directs detailed data questions to the responsible authority. A blank area can mean missing information as well as no mapped exposure under that scenario.

Look beyond the parcel

Our suggested comparison record has three lines: the building, its normal approach road and the route to the relevant evacuation location. Walk those routes in ordinary, safe conditions. Note underpasses, steep sections, stairs and alternatives, then check the local authority's guidance. A dry-looking house does not make every approach usable during an emergency.

Do not visit a riverbank or slope to test conditions during a warning. This pre-purchase exercise is for normal conditions and official information, not an emergency response plan.

Send a specific question to the agent

Use this request as a starting point:

Please confirm the location used for this house. I found it on [map name and date], in [legend category]. Please provide the municipal map and any disclosed flood or slope-related history. Which parts of the access route need separate checking?

Ask an insurer what cover and exclusions would apply to the actual address. Compare the answer with our home insurance guide. Past damage, repairs and the insurability of the home require separate evidence; map colour cannot settle them.

Make the shortlist decision

Give each candidate a status: location unconfirmed, maps checked with questions pending, or evidence ready for professional review. Keep a home with an unresolved hazard question out of the offer-ready group. That is a practical decision rule, not a claim that every mapped property should be rejected.

Browse houses in Japan, choose two candidates and complete the same record for each. Comparing the evidence side by side is more useful than comparing scenery alone.