Estimation of Liquefaction Area Using the Screw Driving Sounding Data in Kumamoto

On April 2016, the Kumamoto earthquake occurred. The earthquake caused serious liquefaction damage in the long and narrow area of about 5 km north and south between the Shirakawa River and the Midori River that flow west through Kumamoto City. In This area is called “Ekijyoka no obi (Liquefaction belt),” and many houses have sunk or tilted. The screw driving sounding test has some advantages including simpler test system and better cost efficiency for penetration in comparison with standard penetration test (SPT) and cone penetration test (CPT). For these reasons, the screw driving sounding test is often used in residential land surveys in Japan, and there is a lot of existing data in this area. In this paper, the spatial information on the Holocene geological situation of this neighborhood was generated made in this area spatial information using the screw driving sounding test data, and the phase change of the liquefied area, and the non-liquefied area was compared. As a conclusion, the spatial extent of the liquefied soil layer was estimated.