9. Characteristics of Re-liquefaction Behaviors of the Typical Soils in the Aso Area of Kumamoto, Japan

The chapter delves into the characteristics of soil liquefaction behaviors in the Kumamoto-Aso area of Japan, focusing on the 2016 earthquakes. It begins by describing the devastating effects of the earthquakes, which induced extensive soil liquefaction and caused significant damage to infrastructure and residential buildings. The unique geological conditions of the area, influenced by the Aso Volcano, are highlighted, particularly the presence of volcanic ash that contributes to the distinctive properties of the local soils. The study investigates the liquefaction and re-liquefaction behaviors of two typical soils: pure volcanic soil (Kuroboku) and soil erupted from sand boiling sites. Through comprehensive tests, the chapter reveals that Kuroboku is highly resistant to liquefaction due to its high fine content, while the erupted soil is more prone to liquefaction due to its higher void ratio. The influence of volcanic ash on the liquefaction behaviors of both soils is also examined, showing a positive effect on liquefaction resistance. The chapter concludes by discussing the implications of these findings for understanding the recurrence of liquefaction in earthquake sequences, emphasizing the need for further research to mitigate future disasters.