Determination of ground properties and pilot experiment for submarine landslide of Ulleung Basin, East Sea

Abstract

This study looks at submarine landslides, which can cause tsunamis and coastal damage worldwide. While submarine landslides are less studied in Korea compared to landslides on land, they are increasingly important due to global tsunami risks. The Korean Peninsula's eastern region, including the Ulleung Basin, has steep terrain and frequent mid-sized earthquakes, making it prone to submarine landslides. Previous research has identified the topographical features and soil properties of these landslide-prone areas in the East Sea. This study focuses on selecting a representative cross-section and geological characteristics of the Ulleung Basin region to conduct dynamic model tests for better understanding and preparedness. The study area is the Ulleung Basin in the East Sea, where submarine landslides are likely to occur, especially along the southwestern border area. The topography here is steep, making it suitable for studying submarine landslides. The 12MAP-53 measurement line was chosen for analysis, as it exhibits significant steepness compared to its surroundings. Selecting the right cross-section to represent submarine landslides is crucial. Boring tests were conducted along this line to understand the seafloor topography. The area mainly consists of clay sediments, with some clay-sand mixture in the upper parts of the slope. For the model tests, kaolinite, a common clay mineral, was selected as the representative geology. Before conducting experiments, various tests were performed on the kaolinite soil, including specific gravity, Atterberg limit, sieve and hydrometer analysis, consolidation test, and direct shear test. These tests provided essential data for the experiments, ensuring that the chosen soil type was suitable for the study. Creating a model slope for dynamic testing involved shaping consolidated kaolin slurry. Silica sand was used for a stable base, and a load of 0.05 kg/cm2 was applied to achieve the desired strength. Natural frequency of the model slope, crucial for understanding its behavior during testing, was determined to be 36.6 Hz. While the study is ongoing, future experiments will involve dynamic testing using a shaking table to simulate real-world conditions.