Parameter characteristics in the early period of three earthquake sequences in the Yutian, Xinjiang since 2008

To investigate the characteristics of various earthquake sequences, we fitted three aftershock sequences of the March 21, 2008 M_S7.3 earthquake, the August 12, 2012 M_S6.3 earthquake, and the February 12, 2014 M_S7.3 earthquake respectively with the epidemic-type aftershock sequence (ETAS) model. We set a unified cutoff magnitude M_c=M_L3.0 and adopted the maximum likelihood method to estimate the parameters α, p and b of these sequences with different duration times. It is observed that the α, p and b value are significantly different for the three earthquake sequences. The α value of 2014 M_S7.3 earthquake sequence is close to the 2012 M_S6.3 earthquake sequence, and larger than that of the 2008 M_S7.3 earthquake sequence; a smaller p value of the 2014 M_S7.3 earthquake sequence indicates that it has a slow decay rate of aftershocks compared with the other two sequences; the b value of 2014 M_S7.3 earthquake sequence is larger than the 2008 M_S7.3 earthquake sequence, but smaller than the 2012 M_S6.3 earthquake sequence. Moreover, the parameters of 2008 M_S7.3 earthquake sequence change significantly within 20 days after the mainshock, while the α and p values of the 2014 M_S7.3 earthquake sequence keep stable in the first 3.5 days.