LOCATION OF SECONDARY FAULTS FROM CROSS-CORRELATION OF THE 2ND VERTICAL DERIVATIVE OF GRAVITY-ANOMALIES

A method is described to locate secondary faults, which can be difficu lt to identify on the Bouguer gravity map. The method is based on cros s-correlation between the theoretical anomaly due to a vertical step a nd the second vertical derivative of the Bouguer anomaly. Faults are l ocated from the closed maxima and minima on the cross-correlation cont our map calculated for two perpendicular directions. One-dimensional m odel computations show that the magnitude of the extremum of the cross -correlation is related to the depth to the top of the hanging wall an d the throw of the fault. Application of the method to the Bouguer gra vity map of the former mouth of the Yellow River in the Shengli Oilfie ld area near the Bo Hai Sea shows the effectiveness of the method.