Applications of a broadband seismic technique in deep seismic exploration

A methodological experiment was successfully carried out at the first Chinese Continent Scientific Drilling(CCSD)site in Donghai,Jiangsu.In the experiment 54France-made compact three-component recorders were employed.Because of the limitation of the recorder and the long profile,the three compo-nents for each recorder were used as three independent stations with three vertical geophones,so that a～180km long profile with more than150'stations' and a dense recording was constructed.Compared with the conventional reflection and wide-angle reflection /refraction,this technique presents some advantages,for example,it has a higher resolution than the wide-angle reflection /refraction and is less expensive than the reflection.Meanwhile,the partitioning-variables velocity imaging method in2D media was used to ob-tain a fine velocity structure beneath the study area,and the moveout for wide-angle reflection made the structure more reasonable.According to the P-and S-wave velocity structure,the Poisson's ratio structure beneath the ultrahigh-pressure metamorphic belt at the CSSD site was established.