PHYSICAL AND ACOUSTIC PROPERTIES OF SHELF SEDIMENTS, THE SOUTH SEA OF KOREA

Abstract

Laboratory determinations of compressional wave velocity, porosity, density and sediment texture have been conducted on samples collected from the inner shelf Holocene mud sediment in the South Sea and southern part of the East Sea of Korea. Thirty-five piston core samples were used for the measurement. Mean grain size decreases seaward reflecting the distance from source. Velocity decreases with increasing water depth. Porosity and clay content increase gradually with deepening bathymetry on the inner shelf. The study area can be divided into three different areas (Namhae, Pusan and Ulsan) by sediment source, texture and physical properties. Velocity increases from west to east (Namhae->Pusan->Ulsan). Porosity has a pattern that is inverse to that of velocity. Sediment texture (mean grain size and clay content) is a very important factor to determine physical and acoustic properties of sediment. The geoacoustic properties of the three study areas generally coincide well with that of Hamilton's (1970) North Pacific continental terrace sediment. Ulsan area is a little different from the Hamilton's model, which has a relatively higher velocity at the same textural range. The difference is believed to be related to the lowest clay content in Ulsan area.