RELATIONSHIP BETWEEN THE MICROTOPOGRAPHY AND OCCURRENCE FACTOR OF LIQUEFACTION IN KUMAMOTO EARTHQUAKE

Abstract

Microtopography is an important component of geographic information with regard to the creation of liquefaction hazard maps. Previous research on microtopography have focused on the high risk of liquefaction, but these studies generally used empirical qualitative evaluations to determine the range and magni-tude of liquefaction in such areas. In the case of the Kumamoto earthquakes of 2016, despite accurate predictions by such maps of areas with high liquefaction risk, there were large discrepancies between the predicted and actual extent of liquefaction. With the aim of improving the accuracy with which the extent of liquefaction could be predicted using geomorphological land classification maps, field evaluations were conducted on liquefied natural levees in Minami-ku, Kumamoto. Furthermore, the relationships between the microtopography and the ground char-acteristics were analyzed. The results showed that the ground composition in the liquefied areas were dif-ferent from those in non-liquefied areas. Based on these findings, we further focused on the transitional processes of microtopographies with high risk of liquefaction and developed an evaluation procedure to predict the range of liquefaction occurrences in areas with similar microtopographies.