Distribution Characteristics of Submarine Landslides in the Ulleung Basin

The Ulleung Basin, located in the East Sea, exhibits numerous submarine landslides along its southern and western slopes, as previously documented. Recent seismic events in the southeastern region of the Korean Peninsula have raised concerns about the potential for additional submarine landslides in the slope of Ulleung Basin. To assess this risk, this study analyzes high-resolution bathymetric data and seismic profiles to establish classification criteria for submarine landslides and identify their distribution patterns. A GIS-based database was developed to catalog the identified features. According to the database, a total of 82 scarps, which represent distinct morphological displacements caused by submarine landslides, were identified. Additionally, 74 deposits, formed by the accumulation of displaced sediment at the base of slopes and within the basin, were mapped. Deposits often overlap in some areas of the basin, making it challenging to delineate their boundaries compared to scarps. The most prominent headscarps, corresponding to steep slope areas, are concentrated at depths of approximately 900 m, with slope angles ranging from 5° to 8°. The average area of identified deposits is approximately 500 km². The study also detected potential scarps that indicate a risk of future submarine landslides. Two of these scarps, which are continuous features, span widths of approximately 13 km and 25 km, respectively. Comparative analysis of seismic profiles and physical property data from deep drill cores obtained in 2019 revealed significant contrasts in sediment properties along the glide planes of existing submarine landslides. These findings suggest that changes in physical properties at the glide plane may play a crucial role in the initiation of submarine landslides in the Ulleung Basin.