Detailed bathymetry and geophysical characteristics of the summit of the Dokdo volcano in the East Sea

Abstract

The Dokdo volcano is situated in the northeastern part of the Ulleung Basin in the East Sea and comprised of very small islets and a large submerged volcanic edifice. There are a big island (Ulleung Island) and three voluminous seamounts (the Anyongbok Seamount, the Simheungtaek and the Isabu Tablemounts) around the Dokdo volcano. Multi-beam, magnetic and sub-bottom profiling survey data for the summit area of the Dokdo volcano obtained from 2004 to 2011 were analyzed to investigate the detailed bathymetry and the geophysical characteristics of the summit of the Dokdo volcano. The bathymetry and topographic data around the islets of the volcano show uneven seabed and irregular undulations from costal line to ~30 m in water depth, indicating the effects of partial erosions and taluses formation due to waves, currents and weathering. The water depth near two main islet (Dong-do and Seo-do) is very shallow (~10 m) (Fig. 1). The area from ~30 m to ~80 m depth has gentle rises and falls, with a modest slope. Below ~80 m, the bathymetry shows relatively flat undulations with a smooth slope, extending to offshore areas. The seabed was found to have stepped slopes, formed mainly due to wave activity and erosion. The stepped slopes is supposed to be coastal terraces suggesting the repetition of transgressions and regressions in the Quaternary. The bathymetry and the seafloor images (from back-scatts (the Anyongbok Seamount, the Simheungtaek and the Isabu Tablemounts) around the Dokdo volcano. Multi-beam, magnetic and sub-bottom profiling survey data for the summit area of the Dokdo volcano obtained from 2004 to 2011 were analyzed to investigate the detailed bathymetry and the geophysical characteristics of the summit of the Dokdo volcano. The bathymetry and topographic data around the islets of the volcano show uneven seabed and irregular undulations from costal line to ~30 m in water depth, indicating the effects of partial erosions a