A STUDY ON THE RELATIONS BETWEEN THE GRAVITY-MAGNETIC REGIONAL AMBIENT FIELD AND THE FAULTS AT THE JUNCTURE OF SHANXI,HEBEI,SHANDONG AND HENAN PROVINCES

In this paper, the maps of the gravity average value, the gravity horizontal gradient value and the gravity horizontal second order differential have been computed and drawn up by the formula and parameters, which had been defined basing on the regional characteristics of the seismogeology and gravitational-magnetic field that are used to make filter analysis and the depth of the earthquakes, in this jucture of Shanxi, Hebei, Shandong and Henan provinces. The results have clearly shown the strikes of the different structures in the crust. Combining with the airborne magnetic analysis information, we have pointed out: There are five latitudinal structural zone. Four of the those faults, except Damin fault, are crossed over Taihang fault zone but formed in different age. Some disputable geological problems of this area, such as the extension of the west termination of the Damin, have been discussed. The boundary and the basement character of the Neihuang uplifted block have been analyzed, Finally. we have discribed the relation between the G-M regional ambient field, faults and the earthquakes distribution, and presented the area where should be paid attention in the future.