[关键词]
[摘要]
本文介绍了国内外关于应力降研究及应用的一些进展。对应力降定义及计算方法进行简要介绍,对地震应力降整体特征、应力降与地震大小、应力降与构造环境、应力降与序列类型等之间的关系进行简要综述,重点讨论了应力降在震后趋势判定中的可能应用,并对应力降计算结果的不确定性进行了初步讨论。应力降表征地震错动导致的位错面上的应力变化,其定义为地震前后初始应力σ0与终止应力σ1之差。地震应力降数值大多为零点几兆帕至数十兆帕,以10MPa以下的居多。应力降与震级、震源深度、构造环境、震源机制、序列类型等之间的关系复杂,对此,也存在诸多不同的认识。消除震级影响之后,地震序列应力降随时间持续升高的现象,对后续强余震有一定的时间指示意义。值得注意的是,诸多因素均会影响应力降的计算结果,数值实验结果显示,拐角频率、零频极限的综合误差对应力降计算结果影响显著,二者不确定性造成的应力降计算误差几乎完全覆盖余震应力降随时间的变化。
[Key word]
[Abstract]
This paper briefly introduces the current research progress in the field of the stress drop both in China and abroad. We briefly describe the definition and calculation method for the stress drop,the overall characteristics of stress drop and the correlation between stress drop and magnitude,tectonic system and other factors. The article focuses on the possible applications of the stress drop in the post-seismic trend determination,and discusses in detail the uncertainty of the stress drop calculation result. Stress drop represents the stress change on the dislocation surface of an earthquake with instantaneous dislocation,which is defined as the difference between the initial stress σ0 before earthquake and the termination stress σ1 of post-earthquake. The stress drop value released by the earthquake is generally between a few MPa to dozens of MPa,most being below 10MPa. The relationship between stress drop and magnitude,source depth,tectonic system,source mechanism and sequence type is complex and different. The stress drop of earthquake sequence increases continuously with time after eliminating the influence of magnitude,which has certain time indication significance for subsequent strong aftershocks. However,it is worth noting that many factors affect the calculation of stress drop. The numerical experiment results show that the combined error of the corner frequency and zero frequency limits has a significant influence on the stress drop calculation result. The error bar almost completely covers variety of the stress drop of the aftershock over time.
[中图分类号]
P315
[基金项目]
中国地震局监测预报能力建设重点专项"震后趋势判定技术系统建设"(2018010205-02)、山东省地震局科技创新团队基金项目(SDST-07-2018)共同资助