Active fault in the southern part of the Yangsan Fault Zone around Samsu-ri, Yangsan, Korea : Samsu Fault

초록

We report a Quaternary fault developed in the southern part of the Yangsan Fault, Korea. The fault displace unconsolidated conglomerates on a slope developed in the river terrace around Samsu-ri, Yangsan, Korea. The unconsolidated conglomerates cut by the fault are the conglomerates derived from Tongdosa area and are mainly composed of granitic and andesitic boulders with a diameter of 5-30 cm. The fault strikes the north-south and dips to the east with high angles. The fault shows apparently the top-up-to-the-east reverse faulting geometry. However, two different slickensides with slip senses observed near fault surfaces indicate a dextral shearing with a reverse-slip component firstly during Quaternary and a dextral strike-slip movement lately. The vertical separation of the fault calculated from the offset of the different layers of unconsolidated sediments and basement, were estimated to be about 7 m.

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