Case Study on Soil Liquefaction Effects in Pohang Using GPR Scanning

Abstract

Owing to the aftershocks of the Gyeongju and Pohang earthquakes, the number of recent earthquakes (more than scale 2.0) has increased by approximately four to five times compared with previous years. There is a high possibility that earthquake damage and liquefaction will be caused by a strong earthquake in the future. Therefore, this study focused on the first liquefaction in Korea, which occurred in the 2017 Pohang earthquake (M5.4), and a field survey was conducted in the damaged area using portable two-dimensional ground penetrating radar (GPR) equipment. A detailed analysis of the damaged areas was performed using Voxler 3 (Golden Software), a three-dimensional analysis program, based on the results obtained at the site. The results show that the six survey areas in Pohang Songdo are located on the Quaternary alluvial layer and include landfills constructed by reclaiming part of the river and seas to create factory, residential land, and other sites, so it is extremely vulnerable to liquefaction in the event of an earthquake. Therefore, it is necessary to conduct a ground survey in advance and apply a countermeasure method that suits the situation of the site because it is feared that large-scale liquefaction damage will occur in the event of a larger earthquake than the Pohang one.