文章摘要

文章信息/Info

Title:: Stability of Parameters of Aftershock Sequence of Qinghai Menyuan M_S6.4 Earthquake in 2016

Author(s):: YU Na; ZHANG Xiaoqing; YUAN Fuquan; Earthquake Administration of Qinghai Province,Xining 810001,Qinghai,China

Keywords:: epidemic type aftershock sequence model; aftershocks sequence; stability analysis; Menyuan M_S6.4 earthquake

摘要:: 采用时间序列的“传染型余震序列”(ETAS)模型和最大似然法,对2016年1月21日门源M_S6.4地震序列参数进行估计。选用截止震级M_C=M_L1.0对门源地震余震序列整体的参数进行连续滑动拟合。结果表明:在主震发生后的早期阶段,α值有明显的不稳定变化,震后3天稳定在1.0～1.4; p值在震后第1～6天由0.98逐渐上升到1.77,其后逐渐下降到1.42,最后相对稳定在1.1～1.3; b值则在震后早期有缓慢升高的变化,但变化幅度不大,由0.77增至0.82,其后稳定在0.81～0.82。门源M_S6.4地震后的早期阶段震源区的应力积累水平逐渐减弱,在序列衰减逐渐减缓的过程中,伴随着激发次级余震能力减弱的现象。

Abstract:: Using time series “epidemic type aftershock sequence”(ETAS)model and the maximum likelihood method,we estimate the parameters of aftershocks sequence of the Menyuan M_S6.4 earthquake on Jan.21,2016,and then select the cutoff magnitude M_C=M_L1.0 to do continuous sliding fitting on these parameters. The result shows the α value changed unstable in the early stage after the main shock,then it was stable in the range of 1.0～1.43 days after the mainshock. The p value increased gradually from 0.98 to 1.77 within 1～6 days after the mainshock and then gradually decreased to 1.42,and finally remained steady at 1.1～1.3. And the b value increased from 0.77 to 0.82 in the early stage after the mainshock,and then remained steady at 0.81～0.82. The stress accumulation level was gradually weakened in the focal area in the early stage after the main shock,and in the process of gradually slowing down the aftershock attenuation,there appeared a weak triggering ability in generating secondary aftershocks.