1. Why Checking Earthquake Risk Matters
Japan is one of the most earthquake-prone countries in the world, making earthquake risk assessment essential when selecting a property. Even within the same municipality, the level of ground shaking can vary significantly depending on soil characteristics and proximity to active fault lines.
While earthquake risk is not a mandatory item in the legally required disclosure statement (juuyou jikousetsu meisho) for real estate transactions, it is a critical factor affecting the safety of your home. By using J-SHIS, provided by the National Research Institute for Earth Science and Disaster Resilience (NIED), you can check earthquake risk at any specific location for free.
2. What Is J-SHIS (Seismic Hazard Information Station)?
J-SHIS (Japan Seismic Hazard Information Station) is a seismic hazard information service operated by the National Research Institute for Earth Science and Disaster Resilience (NIED). It allows users to view data from the National Seismic Hazard Maps published by the Headquarters for Earthquake Research Promotion on an interactive map.
Key Information Available
- - Probability of experiencing seismic intensity 6-lower or greater within the next 30 years
- - Ground shaking vulnerability (surface ground amplification factor)
- - Locations and activity history of nearby active fault lines
- - Distribution of past earthquake epicenters
3. How to Use J-SHIS
You can use J-SHIS by following these steps:
- 1Go to J-SHIS Map (j-shis.bosai.go.jp/map/)
- 2Enter an address in the search bar at the top of the screen
- 3Select "Probabilistic Seismic Hazard Map" from the left menu
- 4Select "Probability of experiencing seismic intensity 6-lower or greater within the next 30 years"
- 5Check the probability for your location using the color-coded map
Tips for Reading the Map
Zooming in reveals more detailed differences in risk between areas. Areas along rivers and reclaimed land tend to have higher risk compared to surrounding areas.
4. Understanding the 30-Year Probability of Seismic Intensity 6-Lower or Greater
The most widely referenced indicator on J-SHIS is the probability of experiencing seismic intensity 6-lower (shindo 6-jaku) or greater within the next 30 years. This probability is calculated for each specific location and displayed using color coding.
| Probability | Risk Level | Reference |
|---|---|---|
| 0-3% | Relatively Low | Areas with comparatively lower risk within Japan |
| 3-6% | Moderate | Areas where a certain level of preparedness is needed |
| 6-26% | High | Many major cities fall within this range |
| 26% or higher | Very High | Areas affected by the Nankai Trough, direct Tokyo metropolitan earthquake, etc. |
Important Note on Interpreting Probabilities
A probability of 3% may seem low, but a 3% chance over 30 years is by no means negligible. For reference, this is significantly higher than the probability of a fire insurance claim event. Even in areas with lower earthquake risk, adequate preparedness is essential.
5. Ground Shaking Vulnerability and Amplification Factors
Even for the same earthquake, the intensity of shaking varies depending on soil characteristics. On J-SHIS, you can check the ground shaking vulnerability as a numerical value called the "surface ground amplification factor."
| Amplification Factor | Ground Characteristics | Shaking Vulnerability |
|---|---|---|
| 1.0 or below | Bedrock / hard ground | Resistant to shaking |
| 1.0 - 1.6 | Moderately firm ground | Average |
| 1.6 - 2.0 | Soft ground (alluvial deposits, etc.) | Prone to shaking |
| 2.0 or above | Very soft ground (reclaimed land, etc.) | Highly prone to shaking |
Lowland areas along rivers, reclaimed land, and sites where ponds or marshes were filled in tend to have higher surface ground amplification factors. These areas are also associated with liquefaction risk and require careful attention.
6. Earthquake Risk Display on JikoDB
JikoDB displays earthquake-related risk information in the "Disaster Risk" section on each property detail page. Based on hazard map data, disaster risk for the property location is automatically assessed.
Area Risk Check Feature
With JikoDB's search function, you can check comprehensive area risk information including earthquake risk simply by entering an address. The ability to check both stigmatized property information and disaster risk in one place is a key feature of JikoDB.
7. Earthquake Risk Checklist for Property Selection
Here is a summary of earthquake risk points to check when evaluating a property:
- ✓Check the 30-year probability of seismic intensity 6-lower or greater on J-SHIS
- ✓Verify that the surface ground amplification factor is not too high (2.0 or above requires caution)
- ✓Check the building's earthquake resistance standard (post-1981 New Aseismic Standard is preferable)
- ✓Confirm there are no active fault lines nearby
- ✓Verify whether the ground is at risk of liquefaction
- ✓Consider purchasing earthquake insurance
Related Pages
* The content on this page is general information and does not constitute legal advice. Earthquake probabilities are based on forecasts, and major earthquakes can occur even in areas with low probability. For the latest information, please refer to J-SHIS (National Research Institute for Earth Science and Disaster Resilience) and the Headquarters for Earthquake Research Promotion.