简慧子,
王丽凤^,,
任治坤,
龚文瑜,
李彦川,
刘金瑞
中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029

基金项目: 国家自然科学基金（41674067）及中国地震局地质研究所中央级公益性科研院所基本科研业务专项（IGCEA1803）联合资助


详细信息

作者简介: 简慧子, 女, 在读硕士, 主要从事断层运动学研究.E-mail:m15275224910_2@163.com

通讯作者: 王丽凤, 女, 博士, 研究员, 主要从事断层运动学和动力学的研究.E-mail:wanglf@ies.ac.cn

中图分类号: P315

收稿日期:2019-09-02
修回日期:2019-12-31
上线日期:2020-03-05

Present-day slip rate and interseismic fault coupling along the Elashan fault using GPS

JIAN HuiZi,
WANG LiFeng^,,
REN ZhiKun,
GONG WenYu,
LI YanChuan,
LIU JinRui
State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China



More Information

Corresponding author: WANG LiFeng,E-mail:wanglf@ies.ac.cn

MSC: P315

--> Received Date: 02 September 2019
Revised Date: 31 December 2019
Available Online: 05 March 2020


摘要
摘要:鄂拉山断裂是位于青藏高原东北缘的一条右旋走滑断裂，前人通过野外地质考察厘定了其万年尺度的长期滑动速率，但对其现今运动学特征的认识仍不足.本文利用近二十年获取的GPS速度场，以贝叶斯理论作为断层滑动反演的理论框架，采用MCMC（马尔科夫链蒙特卡罗）方法，构建鄂拉山断裂的运动学模型，探讨该断裂的现今震间滑动速率和闭锁状态.研究结果表明，鄂拉山断裂的闭锁深度约为15 km，深部的滑动速率为5.0±1.5 mm·a^-1，反映了断层两侧地壳的整体相对运动速率.尽管当前研究区的GPS观测台站分布相对稀疏，但仍可以探测出断层闭锁状态沿走向的变化.在断层中段，由于几何形态的变化，形成了强闭锁的凹凸体，闭锁系数达到0.6~0.7；断层的南段和北段有明显的蠕滑特征，计算得到的闭锁系数仅为0.2~0.3.进一步计算凹凸体上由于滑动亏损产生的等效地震矩积累率为2.35×10¹⁷ N·m/a，等同于M_W5.6地震的能量水平.最后，针对研究区域GPS台站分布稀疏的局限，本研究基于滑动模型的误差最小化准则，给出有限资源条件下的GPS台站优化增设方案.
关键词: 青藏高原东北缘/
鄂拉山断裂/
贝叶斯反演方法/
断层闭锁/
台网优化

Abstract:The Elashan fault is a right-lateral strike-slip fault located on the northeastern margin of the Tibetan Plateau. Although geological investigations have provided its long-term slip rate, the present-day fault kinematics is still poorly understood. In this study, we utilize the interseismic GPS (Global Positioning System) velocity and construct the fault kinematic model in the framework of Bayesian approach using Markov Chain Monte Carlo (MCMC) method, so that to figure out the interseismic creeping/locking along the Elashan fault. The results demonstrate that the locking depth of the Elashan fault is ~15 km, and the deep slip rate is 5.0±1.5 mm·a^-1, i.e., a rate of relative motion between the two blocks at the two sides of the fault. Despite GPS stations are sparse, they provide the resolution of along-strike variations in slip rate. The middle segment with locking coefficients of 0.6~0.7 appears to be strongly locked due to the changes of fault geometry, thus acting as an asperity. The northern and southern segments are characterized by creeping or mild locking, with locking coefficients of 0.2~0.3. The equivalent seismic moment accumulation rate on the asperity is 2.35×10¹⁷ N·m/a, which is equivalent to an M_W5.6 earthquake. Regarding the sparse coverage of the current GPS network, we propose locations for deploying new GPS stations with limited budget based on the rule of minimizing the fault slip uncertainty.
Key words:Northeastern Tibetan Plateau/
Elashan fault/
Bayesian approach/
Fault locking/
Network optimization



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