基于余震粒子群算法的极震区快速判定方法研究

Rapid Determination Method of Magistoseismic Area based on Aftershock Particle Swarm Algorithm

利用1985年以来等震线记录完整的M_S≥6.5地震序列资料,基于余震能量场空间分布,探索利用粒子群算法构造一个震后6h内包含所有主震区激发余震的面积最小椭圆作为估计极震区。统计分析了不同发震方式地震各时段估计震中、微观震中与宏观震中的偏移,以及估计影响场方向、发震断层走向与极震区走向夹角之间的关系。结果表明,余震粒子群算法1h、2h、6h的估计震中都有效缩小了微观震中与宏观震中的偏离。走滑型地震最优估计震中出现在震后2h。倾滑型地震估计震中在震后6h达到最优值。研究显示,走滑型地震和倾滑型地震,震后2h估计影响场方向与极震区走向的夹角均值都小于发震断层走向与极震区走向的夹角均值。走滑型地震震后1h估计影响场方向为最优值,倾滑型地震最优估计影响场方向出现在震后2h。

Using the isoseismal data of greater than Ms6.5 since 1985 and aftershocks energy field, we base on particle swarm algorithm to create the smallest area ellipse which in- cludes all the main excitation aftershocks 6 hours after the quake as the estimated magisto- seismic area. We statistically analyse the distances among the estimated epicenter, the micro- and macro- epicenters of different fracture types in each period, as well as the angle among orientations of the estimate influence field, fault strike and direction of meizoseismal region of different fracture types in each period. The results show that aftershock particle swarm algorithm effectively narrows the deviations of micro- and macro- epicenters. The optimal estimation epicenters of strike-slip type earthquake appear 2 hours after the quake. The optimal estimated epicenters of dip-slip type appear 6 hours after the quake. The study reveals that the mean angle between the direction and orientation of meizoseismal region of the estimated influence field 2 hours after the quake is less than the mean angle of fault strike and orientation of meizoseismal area. The optimal estimation orientations of strike-slip type earthquake appear 1 hour after the quake, while the optimal estimated orientations of dip-slip type appear 2 hours after the quake.