| 2019年四川长宁MS6.0地震前破裂区内视应力和b值的变化 |
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| 作者姓名： | 陈学忠 李艳娥 宫悦 陈丽娟 |
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| 作者单位： | 1.中国地震局地球物理研究所，北京1000812.四川省地震局，成都6100413.重庆市地震局，重庆401147 |
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| 基金项目： | 国家重点研发计划(2018YFC1503405)资助。 |
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| 摘 要： | 视应力和b值都可以反映地壳应力变化。当应力增加时，视应力会增加，而b值降低。因此，应力变化将导致视应力和b值之间呈负相关关系，即，根据视应力和b值之间的负相关关系可以研究地壳构造应力的变化。本文利用2000年1月—2019年12月长宁MS6.0地震破裂区内3.0≤ML≤3.6地震的视应力和2.0≤ML≤4.3地震目录，研究了视应力和b值随时间的变化，发现:2013年2月—2017年3月间，视应力呈趋势上升变化，历时约4年，在震前两年时间内，视应力仍维持在较高水平。在视应力呈趋势上升变化期间，b值则呈趋势下降变化。当视应力维持在较高水平时，b值则维持在较低水平。即，长宁MS6.0地震发生前，破裂区内视应力增加，同时b值下降。这表明，2019年长宁MS6.0地震发生前破裂区内存在明显的构造应力增加过程，对地震孕育过程的认识和地震预测研究都具有启示意义。
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| 关 键 词： | 长宁MS6.0地震 视应力 b值 破裂区 |
| 收稿时间： | 2020-09-24 |
Variations in apparent stress and b value in the rupture area before the 2019 MS6.0 Changning earthquake |
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| Authors: | Chen Xuezhong Li Yan’e Gong Yue Chen Lijuan |
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| Institution: | 1.Institute of Geophysics，China Earthquake Administration，Beijing 100081，China2.Sichuan Earthquake Agency，Chengdu 610041，China3.Chongqing Earthquake Agency，Chongqing 401147，China |
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| Abstract: | Both apparent stress and b value can reveal stress changes in the crust.As the stress increases,the apparent stress increases and the b value decreases.Therefore,the stress variation could result in a negative correlation between apparent stress and b value so that the variation of crustal tectonic stress can be investigated according to this negative correlation.In present study,on the basis of apparent stresses for earthquakes(3.0≤ML≤3.6)and earthquakes(2.0≤ML≤4.3)occurring in the aftershock region of the 2019 MS6.0 Changning earthquake from January 2000 to December 2019,we analyzed the temporal evolutions of the apparent stress and b value.It was found that from February 2013 to March 2017,the apparent stress showed a rising trend lasting for about 4 years.Within the two years before the earthquake,the apparent stress remained at a higher level.During the period when the apparent stress was increasing,b value was decreasing.When the apparent stress maintained at a higher level,b value maintained at a lower level with no distinct change.That is,before the Changning MS6.0 earthquake occurred,the apparent stress in the rupture zone increased,while the b value decreased.It indicates that there is an obvious increase of the tectonic stress in the fracture zone before the MS6.0 Changning earthquake,which has important implications for the understanding of earthquake gestation process and earthquake prediction. |
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| Keywords: | Changning MS6 0 earthquake apparent stress b value rupture area |
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