Structural characteristics of the Binhai Fault Zone in Jiangsu offshore -implications from gravity and magnetic data

The Binhai Fault Zone in Jiangsu offshore is a prominent active fault zone in the western south Yellow Sea, which has undertaken multiple destructive M≥5.0 earthquakes. The local harsh offshore geographical and hydrodynamic conditions limit the marine geological and geophysical surveys, leading to ongoing controversies over its extension, fault-plane structure, kinematics and dynamic properties. Based on qualitative and quantitative analysis of gravity and magnetic data, this study focused on the structural characteristics of the Binhai Fault Zone and adjacent areas, traced the possible location and extension of the fault zone and explored the structural characteristics and kinematics in its different segments. The results show that the Binhai Fault Zone lies about 20~30 km offshore the Jiangsu Province and extends sub-parallel to the coastline. It bifurcates into two branches in the north area to the abandoned Yellow River estuary. The fault zone is roughly divided into three segments by the offshore boundaries of Sheyang city and Rudong city. Its middle segment standing as the eastern boundary of the Subei(North Jiangsu) Basin has deep-rooted faults with long-term inherited activities, the southern segment has younger and the most active strike-slip faults, while the existence and activity of the northern segment need to be further investigated and verified.