ON THE DETERMINING OF SOURCE PARAMETERS OFSMALL EARTHQUAKES BY USING AMPLITUDERATIOS OF P AND S FROM REGIONALNETWORK OBSERVATIONS
LIANG SHANG-HONG LI YOU-MING SHU PEI-YI ZHU PEI-DING (Institute of Geophysics, Academia Sinica)
In this paper, we propose a method for the determination of the source parameters of small earthquakes by means of synthetic seismograms of a point source of dislocation in a plane layered medium, using the maximum amplitude ratios of vertical component of P and S waves recorded by a regional network. We have determined the source mechanism solutions of eight foreshocks of Haicheng earthquake (Feb. 4,1975, Ms=7.3) by using this method from the records of 11-14 stations in Liaoning province, northeast China, and compared with the focal parameters determined by other methods. The results show that the present method has the advantage that it would attain comparable accuracy with less data.