Spatial-temporal Distribution of the Parameters of the Focal Mechanism and Strong Seismicity in Central Yunnan

Adopting the amplitude data of the direct Pg and Sg wave recorded by the Yunnan Digital Seismic Network,using the fast algorithm of the generalized transmission coefficient for the Point Source Dislocation Model for the layered media,we calculate the maximum-amplitude ratios of P and S wave of theoretical seismograms,fit the observed values and get the focal mechanism solution of 206 moderate- and small- earthquakes from Jan.1,1999 to the November 14,2009 in central Yunnan through inversion.We calculate the consistency of focal mechanism parameters of the principal stress axis and the regional tectonic stress field,and analyze the relationship between the spatial and temporal distribution of the consistency of focal mechanism parameters and strong seismicity.The analysis showes that several moderate- and small- earthquakes whose stress-release fields are consistent or approximately consistent with the regional stress field occur near the source region of the strong earthquakes,and strong earthquakes will occur in the low-value area and its fringe of the consistent parameters of the moderate- and small- earthquaqkes.