Liquefaction Prediction Map of Tokyo

The Tokyo Metropolitan Government has launched the "Liquefaction Countermeasures Portal Site for Buildings," where liquefaction-related information for buildings can be viewed collectively. Within this site, tools such as the "Liquefaction Prediction Map of Tokyo" are made available so that building owners and designers can independently engage in liquefaction countermeasures.

Positioning of Liquefaction Prediction Map

• The liquefaction prediction map relatively indicates the possibility of liquefaction when the entire underground area of Tokyo is shaken with a uniform intensity; it does not show the possibility for specific earthquakes such as the metropolitan area directly beneath earthquake.

• The purpose of the liquefaction prediction map is to provide a guideline for liquefaction risk, which is difficult for individuals to investigate, and it does not definitively state that a location will "definitely liquefy or not liquefy." Also, regarding areas with a "low possibility of liquefaction," 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

• Liquefaction assessment is conducted based on boring data, topographic maps, and other materials collected by the Tokyo Metropolitan Government, and does not take into account the effects of liquefaction countermeasures such as ground improvement.

• 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)