Liquefaction forecast map for Tokyo

　The Tokyo Metropolitan Government has set up a "Portal Site for Liquefaction Countermeasures for Buildings" to provide a one-stop access to all information related to liquefaction in buildings. The site contains information such as "Liquefaction Forecast Maps for Tokyo" that enable building owners and designers to take liquefaction countermeasures themselves.

• The liquefaction prediction map shows the relative possibility of liquefaction when the underground of the entire Tokyo metropolitan area is shaken with a uniform strength, and does not show the possibility for a specific earthquake, such as a direct hit of the metropolitan area.
• The purpose of the liquefaction prediction map is to show the risk of liquefaction, which is difficult for individuals to investigate, and it does not determine whether a location will or will not liquefy. Furthermore, even in areas where liquefaction is unlikely, the Tokyo Metropolitan Government does not guarantee that liquefaction will not occur.
• If a liquefaction assessment is required in relation to a land or building transaction, etc., please conduct detailed investigations and examinations at your own responsibility.

• The liquefaction assessment is based on drilling data and topographical maps collected by the Tokyo Metropolitan Government, and does not take into account the effectiveness of liquefaction prevention measures such as ground improvement work.
• Based on the boring data, artificial embankments that do not have a description of the soil type are judged to be made of materials that are not prone to liquefaction. Even if an area is judged to be "low liquefaction risk," there may be a possibility of liquefaction depending on the embankment material.
• Some low-lying areas that have been determined to be "low risk of liquefaction" have ground made of soft clay, which may not be suitable as a foundation for a building if left as is.
• Liquefaction assessments are carried out in units of 250m square mesh, so the possibility of liquefaction may vary depending on the location even within the same mesh.