Detection Of Buried Active Faults In Offshore Sea Of Tianjin

Tianjin offshore sea is located at the intersection part of Hebei plain fault zone and Zhangjiakou-Bohai fault zone,which is the frequently occurred region of strong earthquake in China.The activity of fault system in Tianjin offshore sea is relatively strong,and it has the tectonic setting of occurring moderately strong earthquake.Therefore,finding out the spatial position,distribution feature and activity of these faults,and the geometry characteristic,kinematics characteristic,cutting relation and fault segmentation among these faults,and the prediction of seismic activity has scientific significance and practical significance.This paper has restudied and relocated the concealed faults in Tianjin coastal waters and its activity after the analysis of seismic profile and the collection and re-interpretation of the reflection seismic data on the shallow lands and waters.This paper comes to the following conclusions:(1)Define the space distribution and the characteristics of geometry and kinematics of Haihe Fracture,Haiyi Fracture,QibeiFracture and Qizhong Fracture.Based on gravity magnetic and electronic geophysical datum in some regions,by means of reconstructing and interpreting the seismic datum in the middle and deep stratum,we have processed and imaged newly the shallow artificial detection and seismic detection on water stratum,which also have been combined with the comprehensive detecting method such as drilling exploration to clear the scope of the Haihe fault zone,a sea of fracture,Qibei fracture,the spatial position of Qizhon,the geometry,kinematics features and distribution of fracture within the Tianjin coastal sea.(2)It has determined the size,spatial distribution,tectonic features of the land buried faults in the survey area by analyzing the data acquired through seismic and deep petroleum seismic exploration.The determination of these buried faults provided the basic data for seismic hazard assessment.(3)The results indicates that the most effective concise method of discovering concealed fault is integrated geophysical exploration and drilling data is a direct validation of the prediction results.