Preliminary Interpretation of the crustal wide-angle reflection and refraction experiment along a 300 km survey line of NW-SE direction in South Korea: the Gangwha-Yeongdeok line

The crustal wide-angle reflection and refraction survey was carried out along a 300 km survey line of NW-SE direction in the central and northern parts of South Korea in November 2008. Along the survey line crossing four different tectonic structures, 593 portable seismometers were deployed at stations with approximately 500 m of interval and 8 shots were exploded with charge of shots from 300 to 1500 kg. The preliminary interpretation using 8 record data obtained from this experiment was carried out. Travel-times of P wave phases (Pg, PmP, Pn) and S wave phases (Sg, SmS) were identified. The preliminary result of layered crustal velocity model using forward modeling of 2D ray tracing with P wave phases show that the thickness varies from 30 to 34 km. The crust is thickest below the central part of survey line and it becomes shallower at the ends of northwestern and southeastern along the survey line. This result has similar structural trend to the result of a previous refraction experiment done in December 2002, the survey line of which is parallel to this line and locates at a distance of 100 km south.