Acquisition, processing and interpretation of high-resolution seismic data using a small-scale multi-channel system: an example from the Korea Strait inner shelf, south-east Korea

Abstract

A high-resolution seismic survey was designed to improve the quality of seismic data and study the evolution of inner shelf deposits off the southern coast of Korea. A 0.5 L air gun and 6- or 8-channel streamer cable with a 5 m group interval were used as a seismic source and receiver system, respectively. Data recording was digitally performed at a shot interval of 2 s and a sample interval of 0.1 ms using a personal computer (PC)-based recording system with an analogue to digital (A/D) converter. In the data processing, deconvolution and static corrections were very effective for improving the data resolution. The data resolution and signal-to-noise (S/N) ratio were improved by using multi-channel digital seismic systems as opposed to a single-channel analogue streamer. The results show that a small-scale multi-channel seismic system is an effective way to investigate late Quaternary deposits. Seismic stratigraphic analysis of the high-resolution seismic profiles revealed that inner shelf deposits, up to 30 m thick, consist of three sedimentary units, which comprise transgressive and highstand systems tracts deposited after the last glacial period. The transgressive systems tract includes two units (I and II) separated by a ravinement surface (RS). The lower Unit I, lying below the RS, consists of estuarine sediments left behind by shoreface erosion during transgression, and represents a paralic component. The upper Unit II, including two sub-units (IIa and IIb), lies above the RS and consists of sand produced by shoreface erosion during landward transgression, which corresponds to a marine component. The uppermost Unit III lies above the maximum flooding surface and consists of thick mud clinoforms of the modern Nakdong and Seomjin subaqueous deltas. This unit likely formed during the recent sea level highstand and represents the highstand systems tract.