Seismic reflection imaging of Quaternary faulting offshore the southeastern Korean Peninsula

Abstract

The Yangsan Fault System (YFS) is a dominating tectonic structure in the southeastern part of the Korean Peninsula. The YFS consists of NNE-striking dextral strike-slip faults that are traced to the southeastern coast of the Korean Peninsula. We acquired high-resolution seismic profiles offshore the southeastern Korean Peninsula to investigate how the YFS extends offshore and constrain the age of fault activity using stratigraphic interpretation. The seismic profiles image near-vertical faults trending NE to NNE that constitute a fault zone similar to a duplex structure at a releasing bend of a right-lateral strike-slip fault. The faults are interpreted as an offshore extension of the Ilgwang fault that is a member of the YFS. Stratigraphic interpretation of seismic profiles indicates that the offshore faults were activated repeatedly in the Pliocene and Quaternary. The right-lateral activity of the Ilgwang fault is consistent with the current stress regime in and around the southeastern Korean Peninsula that dictates the P-axis direction in the E-W or ENE-WSW since the Pliocene.