华南地震

2019年6月17日四川长宁发生6.0级地震,截至8月20日总共记录到3级以上余震64次。此次地震发生在一条北西向的隐伏断层。为分析区域地震危险性,综合考虑同震位错和震后粘滞松弛效应,利用PSGRN/PSCMP程序计算地震破裂面上产生的库仑应力变化,分析长宁6.0级地震的长时间尺度库仑应力演化特征及其对3级以上余震的触发作用。结果表明3级以上余震发生在应力触发区概率达到96.9%。同时计算Burgers粘弹性模型的长时间尺度库仑应力动态变化。结果显示应力触发区主要分布在震区的北北西、南南东、北东东和南西西向,将库仑应力动态演化特征应用到本区地震危险性分析时,重点关注上述应力触发区,为后续余震发生提供地点依据。

On June 17th,2019,an MS6.0 earthquake occurred in Changning,Sichuan Province. 64 aftershocks with M≥3 were recorded until August 20th. The earthquake occurred on a buried fault in the northwest direction. To analyze the regional seismic hazard,this paper comprehensively considers the co-seismic dislocation and post-earthquake viscous relaxation effects,uses the PSGRN/PSCMP program to calculate the Coulomb stress change generated on the earthquake rupture surface,and analyzes the long-time scale Coulomb stress evolution characteristics of the Changning M6.0 earthquake and its triggering effect on aftershocks with M≥3. The results show that the probability of aftershocks with M≥3 occurring in the stress triggering zone reaches 96.9%.At the same time,the paper calculates the long-term dynamic Coulomb stress change by using Burgers viscoelastic model. It shows that the stress triggering areas are mainly distributed in the north-north-west,south-south east,north-east and south-west directions of the earthquake area.The paper applies the dynamic evolution characteristics of Coulomb stress to the seismic hazard analysis of this area,and focus on the above-mentioned stress triggering area to provide a location basis for subsequent aftershocks.

引言
1 库仑应力变化
2 计算模型
3 计算结果
4 结论和讨论

图1 长宁地震区域地质构造图<br/>Fig.1 Geological structure of Changning earthquake region

图1 长宁地震区域地质构造图
Fig.1 Geological structure of Changning earthquake region

表1 地壳介质模型<br/>Table 1 Crustal medium model

表1 地壳介质模型
Table 1 Crustal medium model

图2 余震序列的震源深度分布图<br/>Fig.2 Focal depth distribution map of aftershock sequences

图2 余震序列的震源深度分布图
Fig.2 Focal depth distribution map of aftershock sequences

图3 不同深度处长宁6.0级地震同震库仑应力变化及对3级以上余震的触发作用<br/>Fig.3 The co-seismic Coulomb stress change of Changning M6.0 earthquake and its triggering effect on aftershocks with M≥3 at different depths

图3 不同深度处长宁6.0级地震同震库仑应力变化及对3级以上余震的触发作用
Fig.3 The co-seismic Coulomb stress change of Changning M6.0 earthquake and its triggering effect on aftershocks with M≥3 at different depths

表2 主震破裂面上震中位置处的不同深度不同时间尺度库仑应力变化与同震库仑应力变化差值<br/>Table 2 Difference between Coulomb stress changes and co-seismic Coulomb stress changes at different depths and different time scales on the main shock rupture surface of the epicenter location

表2 主震破裂面上震中位置处的不同深度不同时间尺度库仑应力变化与同震库仑应力变化差值
Table 2 Difference between Coulomb stress changes and co-seismic Coulomb stress changes at different depths and different time scales on the main shock rupture surface of the epicenter location

图4 粘弹性模型各个时间点库仑应力变化（η1=1.0x1018Pa∙s、η2=1.0x1019Pa∙s)<br/>Fig.4 The Coulomb stress change of viscoelastic model at various time points(η1=1.0x1018Pa∙s、η2=1.0x1019Pa∙s)

图4 粘弹性模型各个时间点库仑应力变化（η1=1.0x1018Pa∙s、η2=1.0x1019Pa∙s)
Fig.4 The Coulomb stress change of viscoelastic model at various time points(η1=1.0x1018Pa∙s、η2=1.0x1019Pa∙s)

图5 粘弹性模型各个时间点库仑应力变化（η1=1.0x1020Pa∙s、η2=1.0x1021Pa∙s)<br/>Fig.5 The Coulomb stress change of viscoelastic model at various time points(η1=1.0x1020Pa∙s、η2=1.0x1021Pa∙s)

图5 粘弹性模型各个时间点库仑应力变化（η1=1.0x1020Pa∙s、η2=1.0x1021Pa∙s)
Fig.5 The Coulomb stress change of viscoelastic model at various time points(η1=1.0x1020Pa∙s、η2=1.0x1021Pa∙s)

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备注

引言

1 库仑应力变化

2 计算模型

3 计算结果

4 结论和讨论

期刊信息