Abstract: Based on the spectral analysis of moderate and small earthquakes occurred in 2002 in Shanxi reservoir, Wenzhou, Zhejiang Province, we calculated seismic moment M₀, source radius a, stress drop et al. The results show: ① the relation between seismic moment and magnitude: log M₀=1.07 M_L+10.3; ② stress drop of 60% earthquakes are from 0.018 MPa. If>0.049 MPa we think that tress of the earthquake region was anomalous. The stress now is normal; ③ stress drop of earthquake region is fractal, the fractal dimension D=0.85 is a low value; it indicates that strength of media and stress distribution in earthquake region are inhomogeneous.

Key words: Shanxi earthquake swarm, Spectral analysis, Source parameter