为考察2013年4月20日芦山MS7.0地震震后序列参数的早期特征,利用“传染型余震序列”(ETAS)模型和最大似然法进行了参数估计.设定截止震级Mc=ML2.0,拟合时段为震后0.31—24.12天,计算获得α=1.89,p=1.22,同时利用最大似然法估计获得b=0.72.与中国大陆地区其它中强震的余震序列参数的比较表明,芦山MS7.0地震序列参数表现为触发次级余震的能力较弱和序列衰减速率较快的特征,反映出余震区相对较高的应力水平.为检测结果的稳定性,设定不同的截止震级Mc以及不同的拟合截止时间,分别进行参数拟合和参数标准差估计.结果表明,Mc的选取对α值影响明显,对p值影响则较小.此外,震后10天内获得的参数拟合结果随时间变化较为明显,而其后各参数变化总体较为平稳. In order to investigate the early features of the sequence parameters after the MS 7.0 Lushan earthquake on April 20, 2013, the parameters were estimated using the Infectious Involution Sequence (ETAS) model and the maximum likelihood method.The cutoff magnitude Mc = ML2.0, the fitting period is 0.31-24.12 days after the earthquake, α = 1.89 is calculated, p = 1.22, and the maximum likelihood method is used to obtain b = 0.72. Compared with the aftershock sequence parameters of other moderately strong earthquakes in mainland China The comparison shows that the parameters of Lushan MS7.0 earthquake sequence are characterized by weak ability of triggering secondary aftershock and rapid decay rate of sequence, reflecting the relatively high stress level of aftershock zone. The cut-off magnitude Mc, and the different deadlines for fitting, respectively, the parameter fitting and parameter standard deviation estimation were carried out.The results show that the selection of Mc has a significant effect on the α value and a small impact on the p value.In addition, within 10 days after the earthquake The fitting results of the parameters change obviously with time, while the changes of the parameters are generally stable afterwards.