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2019年四川长宁M_(S)6.0地震前破裂区内视应力和b值的变化 被引量:8

Variations in apparent stress and b value in the rupture area before the 2019 M_(S)6.0 Changning earthquake
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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≤M_(L)≤3.6地震的视应力和2.0≤M_(L)≤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M_(S)6.0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M_(S)6.0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。 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 M_(S)6.0 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 M_(S)6.0 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 M_(S)6.0 Changning earthquake,which has important implications for the understanding of earthquake gestation process and earthquake prediction.
作者 陈学忠 李艳娥 宫悦 陈丽娟 Chen Xuezhong;Li Yan’e;Gong Yue;Chen Lijuan(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Sichuan Earthquake Agency,Chengdu 610041,China;Chongqing Earthquake Agency,Chongqing 401147,China)
出处 《地震科学进展》 2021年第2期49-58,共10页 Progress in Earthquake Sciences
基金 国家重点研发计划(2018YFC1503405)资助。
关键词 长宁M_(S)6.0地震 视应力 B值 破裂区 Changning M_(S)6.0 earthquake apparent stress b value rupture area
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