李富珍^1,,
任天翔²,
池顺良³,
张怀^1,,,
石耀霖¹
1. 中国科学院大学地球与行星科学学院, 计算地球动力学重点实验室, 北京 100049
2. 中国地质科学院地球深部探测中心, 北京 100037
3. 鹤壁市地震局, 河南 鹤壁 458000

基金项目: 国家自然科学基金（U1839207，41590865）和国家重点研发计划（2018YFC1504200）共同资助


详细信息

作者简介: 李富珍, 女, 1994年生, 博士研究生, 主要从事地球动力学研究.E-mail: lifuzhen17@mails.ucas.ac.cn

通讯作者: 张怀, 男, 1973年生, 教授, 博士生导师, 主要从事计算地球动力学研究.E-mail: hzhang@ucas.ac.cn

中图分类号: P315

收稿日期:2020-10-14
修回日期:2020-12-22
上线日期:2021-06-10

The dynamic Coulomb stress changes caused by remote earthquakes based on the borehole strainmeter data

LI FuZhen^1,,
REN TianXiang²,
CHI ShunLiang³,
ZHANG Huai^1,,,
SHI YaoLin¹
1. Key Laboratory of Computational Geodynamics, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
2. SinoProbe Center, Chinese Academy of Geological Sciences, Beijing 100037, China
3. Hebi Seismological Bureau, Henan Hebi 458000, China


More Information

Corresponding author: ZHANG Huai,E-mail:hzhang@ucas.ac.cn

MSC: P315

--> Received Date: 14 October 2020
Revised Date: 22 December 2020
Available Online: 10 June 2021


摘要
摘要:已有证据充分证明了大地震远震触发作用的存在.为认识其机理，需要深入探究大地震产生的远场动态应力对断层面应力及断层地震活动性的影响.四分量钻孔应变仪作为超宽频地壳应力监测的重要手段，可以直接记录地震波传来时造成的动态水平应变和应力，这些资料对动态库仑应力变化及其影响的研究有着重要意义，而迄今尚未得到足够重视和应用.本文通过对高台、通化台的四分量钻孔应变仪记录到的2018年太平洋地区4次大地震事件数据进行分析，识别出了P波、S波和面波等不同震相，运用应力花瓣方法分析了它们的特点，计算了它们各自引起的动态应力变化，展示了利用钻孔应变实际观测资料定量研究不同震级大小、不同震中距离的远震地震波在台站位置处的地壳造成动态应力变化的可行性.研究发现，台站位置处动态应力变化的主应力轴方向大体与震中方位角一致，并讨论了对台站附近断层面上动态库仑应力的影响.定量计算结果表明，这4次地震在高台、通化台附近断层面产生的动态库仑应力变化峰值在数百帕量级，低于一般认为的动态触发阈值，也的确没有观测到被动态触发地震活动.但是本文的思路和方法，对今后更大远震可能产生的触发效应提供了研究基础.
关键词: 四分量钻孔应变仪/
应变地震波/
动态触发/
动态库仑应力

Abstract:Sufficient shreds of evidence have proved the existence of the remote triggering effect of large earthquakes. To understand its mechanism,it is necessary to conduct detailed investigations on the influence of the far-field dynamic stress changes on the stress state of faults. As an important tool of ultra-broadband crustal stress monitoring,a four-component borehole strainmeter can directly record the dynamic changes of horizontal strain and stress caused by seismic waves. These data are of great importance to study the dynamic Coulomb stress changes and related triggering effects,but have not been paid sufficient attention to so far. This paper analyzes the data of the four-component borehole strainmeter at Gaotai and Tonghua stations,which recorded the far-field strain changes of four major earthquake events in the Pacific region in 2018. We successfully identify the seismic phases of P,S,and surface waves,and analyze the characteristics of different phases through the stress petal method. The dynamic stress changes are calculated,demonstrating the feasibility of using borehole strainmeter data to quantitatively study the triggering effect of teleseismic waves of earthquakes with different magnitudes at different epicentral distances. We find that the direction of the principal stress axis of the dynamic stress changes is generally consistent with the azimuth of earthquake epicenter. We further discuss the Coulomb stress changes on the major faults near the stations. According to the results,the peak values of the dynamic Coulomb stress changes produced by four earthquakes on the fault planes near Gaotai and Tonghua stations are at the magnitude of hundreds of Pa,which are lower than the threshold value of dynamic triggering. This is also consistent with the observation that no dynamically triggered earthquakes are found on the faults. However,the idea and method of this paper provide useful insight into the detection of possible dynamic triggering of large earthquakes.
Key words:Four-component borehole strainmeter/
Strain seismic waves/
Dynamic triggering/
Dynamic Coulomb stress



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