Natural Disaster Risk & Property in Japan: How to Assess

Reading the hazard map: the hazard map (disaportal)

The first reflex, free and essential: consult the official hazard map kōzui・dosha saigai・tsunamiのhazard map, published on the national portal disaportal.gsi.go.jp (Geospatial Information Authority, Kokudo Chiriin). Type the property's address and overlay the risk layers:

• kōzui / shinsui (kōzui / shinsui): flooding from river overflow — the map shows the expected water depth in a major flood;
• ekijōka (ekijōka): soil liquefaction, typical of reclaimed land or former paddy fields;
• dosha saigai (dosha saigai): landslide and mudflow, on sloping ground;
• tsunami (tsunami): tidal wave, along coastlines.

A property in a red flood or landslide zone is not automatically to be ruled out, but you must know the risk, insure it, and price it in. Always cross-check with the jūyō jikō setsumei (disclosure statement handed over before purchase), which must list the regulatory risk zones. Our buying support runs this check systematically.

The seismic standard: shin-taishin (1981) vs kyū-taishin

The number-one structural criterion in Japan is the seismic standard taishin kijun. A major 1981 reform splits the housing stock in two:

Standard	Building-permit period	Target resistance
kyū-taishin (old)	Before June 1981	Moderate earthquake
shin-taishin (new)	From June 1981	No collapse in a major earthquake

The date that counts is that of the building permit (kenchiku kakunin), not completion. A kyū-taishin property is not to be banned — many have been reinforced (taishin hokyō) — but you must check the seismic diagnosis (taishin shindan) and budget for possible works. We detail this in our dedicated article on the 1981 shin-taishin seismic standard.

⚠ Common mistake

Buying an older property attractive on price without checking its seismic standard. An unreinforced kyū-taishin stacks up a resale discount, a higher insurance premium and real risk. Always have the kenchiku kakunin date verified.

Earthquake insurance (jishin hoken): essential but specific

A crucial point often missed by foreign buyers: ordinary home insurance (kasai hoken) does not cover earthquakes. Seismic damage (and the tsunamis and eruptions that follow) falls under a separate cover, earthquake insurance jishin hoken (jishin hoken).

• it is taken out as a rider to fire insurance kasai hoken, never on its own;
• it is partly backed by the State and capped (generally 30–50% of the fire-insured value);
• the premium depends on the zone (prefecture) and the structure (wood vs concrete), with discounts for shin-taishin or recent buildings.

For an investor, this premium is part of the annual costs: fold it into your net-yield calculation with our yield simulator.

Typhoons, soils and fill: risks not to forget

Typhoons taifū

Every year, from summer to autumn, typhoons bring violent winds and torrential rain, especially in Okinawa, Kyushu and along the Pacific coast. To check: roof condition, waterproofing, exposure, and — for a riverside property — the associated flood risk (see the hazard map).

Soils and fill moritsuchi

The nature of the soil governs behaviour in an earthquake. Two watch points:

• fill land (moritsuchi), created by filling a slope or valley, is more exposed to landslides and settlement — a regulatory framework (moritsuchikisei-hō) has recently governed it;
• soft soils (former paddy fields, coastal areas) are prone to liquefaction ekijōka.

This information cross-references between the hazard map, geological maps and the jūyō jikō setsumei. See also how these risks feed into 2026 property prices by region.

The risk checklist to run before buying

Here is the control grid we apply to every property, with where to find each piece of information:

Risk to check	Japanese term	Where to look
River flooding	kōzui / shinsui	hazard map (disaportal)
Soil liquefaction	ekijōka	hazard map + geological map
Landslide	dosha saigai	hazard map
Tsunami	tsunami	hazard map (coast)
Building seismic standard	shin-taishin / kyū-taishin	Permit date kenchiku kakunin (before/after June 1981)
Fill land	moritsuchi	Land history, jūyō jikō setsumei
Regulatory risk zones	jūyō jikō setsumei	Disclosure statement given before sale

The jūyō jikō setsumei (jūyō jikō setsumei), mandatorily provided by the agent before signing, must list the official risk zones: read it carefully — it is a legal document. Our listings are pre-filtered on these criteria, and the full step-by-step is in the buying guide.

In short: risk is to be checked, not ignored

Japan is highly exposed to earthquakes and weather, but the risk is very well mapped and manageable. The method is four moves: 1) consult the hazard map (flood, liquefaction, landslide, tsunami); 2) check the shin-taishin seismic standard via the kenchiku kakunin permit date; 3) take out earthquake insurance jishin hoken on top of kasai hoken; 4) read the jūyō jikō setsumei.

A well-located, compliant and properly insured property is held without fear. Conversely, a price that is too low often signals an untreated risk. Fold these costs into our simulator, cross-check with 2026 price trends, and get support for the full check.

Frequently asked questions

How do you check a property's natural-disaster risk in Japan?

First consult the official hazard map hazard map on disaportal.gsi.go.jp: type the address and overlay the flood kōzui, liquefaction ekijōka, landslide dosha saigai and tsunami tsunami layers. Then cross-check with the jūyō jikō setsumei disclosure handed over before purchase, which lists the regulatory risk zones.

What is the 1981 shin-taishin seismic standard?

It is the seismic standard applying to building permits issued from June 1981, designed so a building will not collapse in a major earthquake. Older properties (kyū-taishin) offer less resistance; check the permit date kenchiku kakunin and whether reinforcement taishin hokyō has been done before buying.

Does home insurance cover earthquakes in Japan?

No: ordinary fire insurance kasai hoken does not cover earthquakes. You must add earthquake insurance jishin hoken as a rider, partly State-backed and capped (often 30–50% of the fire-insured value). The premium depends on the prefecture and the building's structure.

Is fill land (moritsuchi) risky?

It calls for extra care: land created by filling a slope is more exposed to landslides and settlement in an earthquake or heavy rain. A regulatory framework (moritsuchikisei-hō) now governs it. Check the land history and the hazard map before buying.

Should you avoid flood or earthquake risk zones?

Not necessarily: risk in Japan is mapped and insurable. A property in an identified zone can still be a good buy if it is compliant, properly insured and the risk is priced in. But an abnormally low price often signals an untreated risk you should quantify before making an offer.