CHARACTERISTICS OF THE FOCAL MECHANISM FOR PARTS OF MODERATE AND SMALL EARTHQUAKES IN SHANDONG AND ITS NEIGHBORING REGION

The waveform data of 20 medium earthquakes recorded by Shandong and its neighboring Province from 2001 to Apr.2006 is collected, and the earthquake is relocated.Based on the first motion of P wave, SV wave, SH wave and their amplitude ratio, the focal mechanisms of the 20 earthquakes are calculated with Snoke program.The results show that the fracture of faults is mainly strike slip, which is dextral for the faults in NE direction, and sinistral for the faults in NW direction.Most earthquakes occurred on the current faults, and the fracture direction is consistent with the structure of the fault.It is concluded that the facture of medium and small earthquake is controlled by current fault structure.