2001年昆仑山口西MS8.1地震自发破裂过程数值模拟研究  

Numerical simulation of spontaneous rupture process of the 2001 MS8.1 west of Kunlun pass earthquake

作　　者：奉建州 廖力[1,2] 李平恩 吴庆举[1] FENG JianZhou;LIAO Li;LI PingEn;WU QingJu(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Beijing Baijiatuan Earth Sciences National Observation and Research Station,Beijing 100095,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]北京白家疃地球科学国家野外科学观测研究站,北京100095

出　　处：《地球物理学报》2024年第6期2141-2158,共18页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41674105);中国地震局地球物理研究所基本科研业务费专项(DQJB19B27,DQJB22Z02,DQJB23Y32)联合资助.

摘　　要：2001年11月14日,青藏高原的东昆仑断裂带发生昆仑山口西MS8.1地震,现场考察和破裂过程反演结果表明这是一次破裂过程非常复杂的走滑地震事件.研究这次地震的自发破裂过程,对于认识大陆型特大地震的发生机理具有重要意义.本文利用曲线网格有限差分法对2001年昆仑山口西MS8.1地震的动力学破裂过程进行研究.首先建立能反映这次地震主要特征的三维非平面断层模型,并以地质考察、以及根据GPS和InSAR观测数据、远场地震记录得到的反演结果为约束,通过数值模拟重现了这次地震破裂过程的主要特征.在此基础上,进一步讨论了背景应力场、断层几何、摩擦系数对断层面滑移量分布、震源时间函数、破裂传播速度的影响.研究结果表明,昆仑山口西MS8.1地震发展成为具有超长破裂尺度的大型地震的重要原因可能是:青藏高原最大水平主压应力方向沿东向的顺时针旋转特征和断层面较低的动摩擦系数.并且沿昆仑山口西地震断层面的动摩擦系数可能是非均匀的,由此产生了沿断层走向复杂变化的应力降,从而导致超剪切破裂的发生,并控制了断层面滑移量分布.On November 14,2001,the MS8.1 west of Kunlun pass earthquake occurred in the East Kunlun fault zone of the Qinghai-Xizang Plateau.The results of the field investigation and the rupture process inversion show that this earthquake is a strike-slip earthquake event with a very complex rupture process.Studying the spontaneous rupture process of this earthquake is significant for understanding the mechanism of great continental earthquakes.In this paper,the dynamic rupture process of the 2001 MS8.1 west of Kunlun pass earthquake is investigated by using the curved grid finite-difference method(CG-FDM).First,a 3-D non-planar fault model is established,which can represent the main characteristics of the earthquake fault.Constrained by the geological survey,and the inversion results from GPS and InSAR observation data,as well as far-field seismic records,the main characteristics of the earthquake rupture process are reconstructed by the numerical simulation.Then,the influence of background stress field,fault geometry,and frictional coefficient on the fault plane slip distribution,source time function,and rupture propagation velocity are discussed in more detail.The results show that,the clockwise rotation characteristics of the maximum horizontal principal compressive stress along the eastern direction in the Qinghai-Xizang Plateau and the low dynamic friction coefficient on the fault plane may be two important reasons that the MS8.1 west of Kunlun pass earthquake developed into a large earthquake with an ultra-long rupture scale.And the dynamic friction coefficient along the fault plane of this earthquake may be non-uniform,resulting in a complex stress drop along the fault strike,which leads to the occurrence of super-shear rupture and controls the distribution of slip on the fault plane.

关 键 词：昆仑山口西MS8.1地震 曲线网格有限差分法 自发破裂过程 同震滑动量分布 超剪切破裂 

分 类 号：P315[天文地球—地震学] P313[天文地球—固体地球物理学]