INTERDISCIPLINARY APPROACHES TO UNDERSTANDING NEOTECTONIC FAULT EVOLUTION OF SOUTHEASTERN TIP OF KOREAN PENINSULA

Neotectonic modeling applied to the characterization and evaluation of southeastern area of Korean peninsula as a national nuclear power plant has been approached by digital mapping of neotectonic fault, trace mapping of marine and river terraces, paleoseismological observation, age dating, paleomagnetic reconstruction, geophysical exploration and GPS data since 2000. Right lateral strike-slip fault movement has been occurred to the southeastern area during Eocene to the Early Quaternary. Tectonic stress resume has changed to reverse faulting toward the west since the Early Pleistocene. Geometrical complex of neotectonic faults was denuded to transpressional shear fault segments undergone left lateral strike-slip fault movement due to clockwise trans-rotation since late Miocene. Those segments are intermittently distributed along NS trend with left step pattern and show oblique strike-slip fault movement with reverse sense toward the west. Master fault of the rotation was based on opening of the East Sea between Korean peninsula and Japanese Island Arc. The master fault had an extensional right lateral strike-slip movement with SE trend as a southern tear fault of the East Sea block. However, due to subduction of the Pacific Plate toward the west of northwest rather than that of the Philippine plate toward the north of northwest, tectonic stress resume to the East Sea has been changed toward the west and gave an effect of left lateral strike-slip movement to the master fault. As a result, the southeastern tip of Korean peninsula has an overprint of reverse sense on the strike-slip fault plane at present time.