Bathymetry and Sidescan Imagery of SeaBeam2000 Multi-Beam Echo Sounder on the Eastern Ulleung Basin, East Sea of Korea(Japan Sea)

초록

SeaBeam2000, a multi-beam echo sounder, is a new generation seafloor mapping system of which a single swath covers an angular range of -60 to 60 degrees from the vertical direction with 121 beams. It provides high density and high quality bathymetry data along with side scan like amplitude imagery. The purpose of this article is to present a post-processed SeaBeam bathymetry and 121 returning amplitude imagery using digial image processing techniques. As a processing to convert vector-formatted SeaBeam data into raster image mosaic, the following procedures are described: interpolation of unsampled beam data, removal of outliers, spatial registration of various types of data, and position correction of data in equi- spatial grid resolution. Even though the side scan imagery is fully corrected in real time for variations in ship speed and direction, it has low contrast due to the attenuation of side scan like returing amplitude signals along the horizontal range across the ship track. The results of the processed side scan image from the survey area reveal a newly discovered channels which develop into the lower slope regions(center of the surveyed area) to deep bottom(2,300m) and there are many slope failure accompanied by slumping sliding, debris flows and turbidity current at the southern high slope region of Dok Island and around the submerged topographic heights. On the other hand, large amounts of sediments were moved to deep water bottom along the channels during slope failures. The channel in this region affected by strong bottom current speed and directions.