Estimating stress drop of the 2013 Lushan earthquake sequence based on the empirical Green’s function spectral ratio method

We adopted the 2013 Lushan aftershocks as a typical example, to investigate the feasibility of estimating corner frequency and stress drop by the empirical Green’s function （EGF） spectral ratio method based on the strong motion observation data. Firstly, we suggested the quality standard on the EGF spectral ratio curve to guarantee the reliable estimation of seismic corner frequency and stress drop. The corner frequencies for the 17 Lushan aftershocks with magnitude in the range of 3.8−5.4 were then estimated. Referring to the seismic moment magnitude given by other studies, we further computed the seismic stress drops.The results show that the corner frequency of Lushan strong aftershocks is mainly in the range of 1.0−2.0 Hz, the average stress drop is 9.98 MPa, and seismic stress drop presents obvious dependency on seismic magnitude.