Preliminary test on possible usage of Radon for potential shallow subsurface fault detection in the Gunsan Basin, West Sea of Korea

Abstract

This study focuses on 222Rn tracer in bottom seawater in order to identify shallow subsurface faults possibly extending from deep-seated faults, in the Gunsan Basin (West Sea of Korea). The bottom seawater samples were obtained at five stations, using a multi-corer on board the R/V Onnuri. Four stations are located at potential shallow subsurface faults inferred from reflection seismic profiles. The rest is a station in the area without shallow subsurface faults. Relatively high levels of 2Rn concentration in the bottom seawater samples were measured at the stations adiacent to the inferred shallow subsurface faults with a maximum value of 26+10 Bg m , while the concentration at the station without faults was below the detection limit (4+2 Bg m 3). This preliminary study suggests that the distribution of 222Rn in the bottom seawater may be associated with the presence or absence of the subsurface faults and can be used as a complementary approach for identifying possible shallow subsurface faults.