Liquefaction Prediction Map of Tokyo

In Tokyo, a "Liquefaction Countermeasure Portal Site" has been established to provide consolidated information on liquefaction related to buildings. Within this site, resources such as the "Tokyo Liquefaction Prediction Map" are available for building owners and designers to actively engage in liquefaction countermeasures.

Positioning of Liquefaction Prediction Map

• The liquefaction prediction map relatively indicates the potential for liquefaction when the underground of the entire Tokyo Metropolitan area is shaken uniformly, and it does not indicate the potential for specific earthquakes such as those directly beneath the metropolitan area.

• The liquefaction prediction map is intended to provide a guideline for the risk of liquefaction occurrence, which is difficult for individuals to investigate. It does not definitively state that a location will "absolutely liquefy or not liquefy." Additionally, regarding areas with a "low possibility of liquefaction," the Tokyo Metropolitan Government does not guarantee that liquefaction will not occur.

• If liquefaction assessment is necessary for land and building transactions, please conduct a detailed investigation and examination at your own responsibility.

About Liquefaction Assessment

• The liquefaction assessment is conducted based on boring data and topographic maps collected by Tokyo Metropolitan Government, and the effects of liquefaction countermeasures such as ground improvement are not taken into account.

• Based on the boring data assessment, among the artificial embankments, those without a description of soil quality are judged to be materials that are less likely to liquefy. Even in areas assessed as having a low possibility of liquefaction, there may be a risk of liquefaction depending on the embankment materials.

• Among the areas determined to have a low possibility of liquefaction in low-lying areas, there are locations with weak clay soil, which may not be suitable as a foundation for buildings as is.

• Liquefaction assessment is conducted in mesh units of 250 meters square, so the possibility of liquefaction may vary depending on the location even within the same mesh.

• Liquefaction Countermeasure Portal Site for Buildings (Tokyo Metropolitan Bureau of Urban Development)(External Link)
• Liquefaction Prediction Map of Tokyo (Tokyo Metropolitan Civil Engineering Technical Support and Human Resource Development Center)(External Link)