付广裕^1,2,,
王振宇²
1. 中国地震局地震预测研究所, 北京 100036
2. 中国地震局地球物理研究所, 北京 100081

基金项目: 国家自然科学基金（41874003），新疆精河6.6级地震深入科学研究项目与中国地震局地震预测研究所基本科研业务费专项（2016IES010204）联合资助


详细信息

作者简介: 付广裕, 男, 研究员, 主要从事地震位错理论以及重力数据解析研究.E-mail:fugy@ief.ac.cn

中图分类号: P312

收稿日期:2019-04-23
修回日期:2019-05-16
上线日期:2020-06-05

Crustal structure, isostatic anomaly and flexure mechanism around the Jinghe M_S6.6 earthquake in Xinjiang

FU GuangYu^1,2,,
WANG ZhenYu²
1. Institute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, China
2. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China


MSC: P312

--> Received Date: 23 April 2019
Revised Date: 16 May 2019
Available Online: 05 June 2020


摘要
摘要:依据EIGEN-6C4重力模型和ETOPO1高程模型数据，围绕新疆精河6.6级地震展开岩石圈均衡与挠曲机理研究，得到如下结论：（1）震中附近的布格与自由空气重力异常分别为-221和-92 mGal（10^-5m·s^-2），震中位于重力异常高梯度带上；（2）震中周边地区地壳厚度约为50 km，密度结构总体变化平缓，东西方向地壳厚度变化较小，但自南向北地壳厚度逐渐变薄，精河6.6级地震初始破裂发生在上中地壳分界面附近；（3）震中附近岩石圈承载的垂向构造应力为20 MPa左右，震中位于岩石圈垂向构造应力极大值附近的高梯度带上；（4）地震周边地区岩石圈有效弹性厚度最优解为26 km，加载比最优解为F₁=1，F₂=F₃=0，表明该区域岩石圈相对坚硬，且导致岩石圈变形的初始加载全部来自地表.
关键词: 精河6.6级地震/
EIGEN-6C4重力模型/
布格重力异常/
岩石圈垂向构造应力场/
岩石圈有效弹性厚度

Abstract:Based on the data of EIGEN-6C4 gravity model and ETOPO1 elevation model, this paper studied the gravity anomaly, lithospheric isostatic state as well as the flexure mechanism around the Jinghe M_S6.6 earthquake in Xinjiang, and reached the following conclusions. (1) We obtained the Bouguer and free-air gravity anomalies according to the above gravity and elevation data. The Bouguer gravity anomaly near the epicenter is about -221 mGal (10^-5m·s^-2), and the free-air gravity anomaly is about -92 mGal. The epicenter is located in the high gradient zones of the Bouguer and free-air gravity anomaly fields. (2) We inversed the crustal density structures around the Jinghe M_S6.6 earthquake using the Bouguer gravity anomaly data. The crustal thickness around the epicenter is about 50 km, and the density stratification structure changes gently as a whole. There is no obvious change in the crustal thickness in the East-West direction, but the crustal thickness gradually thins from south to north. The initial rupture of the Jinghe M6.6 earthquake occurred near the surface between the upper and middle crusts. (3) We calculated the vertical tectonic stress of the lithosphere using both the Bouguer gravity anomaly data and the ETOPO1 elevation data. The vertical tectonic stress near the epicenter is about 20 MPa, and the one in the surrounding area is positive as a whole. The epicenter is located in the high gradient belt near the maximum of the vertical tectonic stress (about 40 MPa). (4) According to the above free-air gravity anomaly data, we studied the flexure mechanism around the Jinghe M_S6.6 earthquake through the gravity admittance method. The optimal effective elastic thickness of lithosphere around earthquake is 26 km, and the optimal loading ratio is F₁=1, F₂=F₃=0, which indicates that the lithosphere in this area is relatively hard, and the initial loading of lithosphere deformation comes from the Earth surface completely.
Key words:Jinghe M_S6.6 earthquake/
EIGEN-6C4 gravity model/
Bouguer gravity anomaly/
Vertical tectonic stress of the lithosphere/
Effective elastic thickness of the lithosphere



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