Investigation on deep crustal structure along the onshore-offshore seismic profile near Hongkong
香港地区海陆地震联测及深部地壳结构研究

In order to investigate the deep crustal structure across the transition zone between land and sea of northern South China Sea, an onshore-offshore deep seismic experiment was carried out offshore Hong Kong. The permanent seismic stations of Guangdong and Hong Kong region were used to record the air-gun signals for the first time. We could identify different seismic phases and clear signals from more than 200 km distance. The deep crustal structure was studied along Profile 1. The results show that the crustal structure has strong heterogeneous characteristics. The sediments become thicker seaward. The Moho depth is about 26~29 km. The P-wave velocity is about 5.6~6.4 km/s in the upper crust, and about 6.5~6.9 km/s in the lower crust. There is a low velocity zone seaward of DanGan Islands, where the P-wave velocity is about 5.3~6.2 km/s in the upper crust and about 6.3~6.7 km/s in the lower crust. it may be the Binhai (littoral) fault zone according to former studies. The depth of Moho discontinuity change a little larger landward of DanGan Islands, it maybe relate with HaiFeng fault zone.