Brief Communication: A case study of risk assessment for facilities associated with earthquake-induced liquefaction potential in Kimhae City, South Korea

Abstract. Liquefaction causes secondary damage after earthquakes; however, liquefaction related phenomena were rarely reported until after the Mw = 5.4 November 15, 2017 Pohang earthquake in Korea. Both the Mw = 5.8 September 12, 2016 Gyeongju earthquake and Mw = 5.4 November 15, 2017 Pohang earthquake occurred in the fault zone of Yangsan City (located in the south-eastern part of Korea), and both of these earthquakes induced liquefaction. Moreover, they demonstrated that Korea is not safe against the liquefaction induced by earthquakes. In this study, estimations and calculations were performed based on the distances between the centroids of administrative districts and an epicenter located at the Yangsan Fault, the peak ground accelerations (PGAs) induced by Mw = 5.0 and 6.5 earthquakes, and a liquefaction potential index (LPI) calculated based on groundwater level and standard penetration test results from 274 locations in Kimhae City (adjacent to the Nakdong river and across the Yangsan Fault). Then, a kriging method using geographical information systems was used to evaluate the liquefaction effects on the risk levels of facilities. The results indicate that a Mw = 5.0 earthquake induces a small and low level of liquefaction, resulting in slight risk for facilities, but a Mw = 6.5 earthquake induces a large and high level of liquefaction, resulting in a severe risk for facilities.