尹凤玲^1,,
韩立波¹,
蒋长胜¹,
石耀霖²
1. 中国地震局地球物理研究所, 北京 100081
2. 中国科学院计算地球动力学重点实验室, 中国科学院大学, 北京 100049

基金项目: 国家重点研发计划(2017YFC1500501)资助


详细信息

作者简介: 尹凤玲, 女, 助理研究员, 主要从事地球动力学和地震预测研究.E-mail:yin_fengling@126.com

中图分类号: P315

收稿日期:2017-12-10
修回日期:2018-03-15
上线日期:2018-08-05

Interaction between the 2017 M6.9 Mainling earthquake and the 1950 M8.6 Zayu earthquake and their impacts on surrounding major active faults

YIN FengLing^1,,
HAN LiBo¹,
JIANG ChangSheng¹,
SHI YaoLin²
1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
2. Key Laboratory of Computational Geodynamics of Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing 100049, China


MSC: P315

--> Received Date: 10 December 2017
Revised Date: 15 March 2018
Available Online: 05 August 2018


摘要
摘要:2017年11月18日，我国西藏林芝市米林县发生M6.9地震.其东南220 km距离处，1950年发生了察隅8.6级大地震.二者同处喜马拉雅东构造结大拐弯处，周边分布多条活动断裂带.察隅地震作为20世纪我国内陆最大的地震，它的发生对周边断层活动性的影响目前研究尚少.本文基于分层半无限空间黏弹性地球模型，计算了察隅地震对周围活动断裂带和米林地震的影响，同时利用有限断层破裂模型计算了米林地震对周边活动断层产生的同震库仑应力变化，并分析了两次地震的关系，讨论了下地壳及以下介质的黏滞系数和断层有效摩擦系数对计算结果的影响.结果表明，察隅地震影响范围广、强度大且持续时间长，对喜马拉雅东构造结周边活动断层均产生了较大的影响，库仑应力变化达到数MPa量级.在下地壳黏滞系数为1.0×10²⁰ Pa·s、摩擦系数为0.4情况下，按照青藏高原主要活动断裂每年由正常构造运动应力累积1~4 kPa计算，察隅地震的发生使米林地震提前了相当于2.79~11.15年的时间.米林6.9级地震影响范围和强度有限，只对震源附近的活动断层产生一定影响，库仑应力变化最大为数十kPa量级，对远处的断层影响较小.下地壳及以下介质的黏滞系数在震后黏滞松弛过程中影响逐渐明显，断层有效摩擦系数对同震库仑应力计算影响较大.
关键词: 米林地震/
察隅地震/
黏弹松弛/
有效摩擦系数/
库仑应力变化

Abstract:On November 18, 2017, an M6.9 earthquake occurred in the Mainling County, Nyingchi Region of Tibet, China. Several strong earthquakes including the great M8.6 Zayu earthquake in 1950, about 220 km to the southeast of the Mainling earthquake, occurred in this region. Both Zayu and Mainling earthquakes located at the corner of the Eastern Himalaya Syntaxis, where a number of large active faults were recognized. The 1950 M8.6 Zayu earthquake was the largest one in continental China in the last century and its impact on major active structures was still under debated. Based on a stratified viscoelastic earth model, we calculated the Coulomb stress changes imparted by the Zayu earthquake and Mainling earthquakes on major active faults in this region. The results show that Zayu M8.6 earthquake has a wide, intense and long-time impact on major active faults around the Eastern Himalaya Syntaxis, the absolute value of Coulomb stress changes could be as large as 1 MPa. Given a stress accumulation rate 1~4 kPa/a due to tectonic loading and assuming a lower crust viscosity coefficient of 1.0×10²⁰ Pa·s and an effective friction coefficient of 0.4, the Mainling earthquake was advanced 2.79~11.15 years by the Zayu earthquake. As a comparison the resolved Coulomb stress changes on surrounding faults caused by the Mainling earthquake were on the order of tens of kPa and even smaller on the distant faults, thus its effect could be neglected. We also investigated the influence of the viscosity coefficient of lower crust and mantle and the effective friction coefficient along faults on the results. The viscosity coefficient of lower crust and mantle played a significant role in the postseismic relaxation, and the effective friction coefficient also largely affected the coseismic Coulomb stress changes.
Key words:Mainling earthquake/
Zayu earthquake/
Viscoelastic relaxation/
Effective friction coefficent/
Coulomb stress change



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