Fracture Geometry Feature of the Northwest-Pacific Subduction Zones

Based on P-wave travel time of seismic data, processed using the double difference tomography method, the hypocenter relocation results and P-wave velocity structure within the range of 0~70 km beneath the Pacific ocean subduction zones can be obtained. Combining with the bathymetric data and fracture feature data, we obtained the fracture geometry feature within the range of 0~70 km beneath the Northwest of the Pacific Ocean subduction zones and identified the fracture classification of Northwest-Pacific subduction zones. 1-level fractures include Itoigawa-Shizuoka Tectonic Line (ISTL), Tartary Fault (TF), Tartary-Tanakura Fault (TTF), Tartary-Ishikari Fault (TIF), East Japan Sea Fault (EJSF), Centre Hokkaido Sakhalin Fault (CHSF), Abashiri Fault (AF), the South of the Kuril Basin Boundary (KBB2), the West of Okhotsk Fault (WOF), the East of Okhotsk Fault (EOF). 2-level fractures include Median Tectonic Line (MTL), Hatagawa Tectonic Line (HTL), the North and the South of the Japan Basin Boundary (JBB1, JBB2), Hokkaido Faults(R8-fault, R9-fault, R10-fault, R11-fault, R12-fault, R13-fault), the North of the Kuril Basin Boundary (KBB1), East Sakhalin Fault (ESF), Okhotsk Faults(S1-fault, S2, S3)、Kamchatka Faults (Ka1-fault, Ka2-fault, Ka3-fault, Ka4-fault). The number of 3-level and above level fractures is large, such as R1~R7 faults, R14~R25 faults which are reverse faults and N1~N4 faults which are normal faults.