摘要
为了研究应力场类型与震源机制解类型之间的关系,本文基于三维应力莫尔圆分析断层滑动的不稳定系数大小对产生震源机制解类型的影响,获得了三种典型应力场作用下可以产生的震源机制解类型及其影响因素,主要结论如下:(1)当断层滑动所需的不稳定系数接近于1时(断层不稳定系数范围为0~1,0为最难滑动,1为最易滑动),走滑型、拉张型和挤压型应力场主要产生与各自性质一致的震源机制解;当不稳定系数小于1时,各种应力场可以产生异于应力场类型的震源机制解.断层滑动所需的不稳定系数越低,各种类型应力场产生的震源机制解类型越丰富;不同类型应力场产生的震源机制解类型不但受控于应力场类型,而且受控于断层滑动所需的不稳定系数.(2)震源机制解类型主要受控于应力场类型和断层参数,其他因素如应力比、断层摩擦系数、断层孔隙压和断层剪切强度等对产生的震源机制解类型也有一定的影响.(3)应力比对不同参数断层的不稳定系数影响较大,但对不同类型应力场作用下不稳定系数随走向和倾角分布的总体特征影响较小,不稳定系数高值区域中心的断层参数由具体应力场参数及断层摩擦系数确定.本研究可为震源机制解类型多样性、应力场均匀性、断层摩擦强度、断层上孔隙压大小等相关研究提供参考.
To investigate the relationship between the stress regime and the type of focal mechanism solution,we employ the three-dimensional stress Mohr circle to analyze the influence of the instability coefficient value of sliding fault on the type of focal mechanism solution.The generated focal mechanism solution types and their influencing factors under the action of three typical stress regimes are obtained.The following conclusions are drawn:(1)When the instability coefficient for fault sliding approaches 1(the range of fault instability coefficient is 0~1,where 0 indicates the most difficult to slip and 1 indicates the easiest to slip),the stress regimes of strike-slip faulting,normal faulting,and thrust faulting mainly generated focal mechanism solutions consistent with their respective properties.When the instability coefficient is lower than 1,focal mechanism solutions different from the stress regime can be generated.It can be observed that the lower instability coefficients for fault slip,the more focal mechanism solution types generated by various stress fields.Types of focal mechanism solution generated by different stress field types are not only controlled by the stress regime but also influenced by the fault instability coefficient required for fault slip.(2)The types of focal mechanism solution are mainly controlled by stress field types and fault parameters,but the stress ratio,friction coefficient,pore pressure and shear strength of fault have some influence on the generated focal mechanism solution types.(3)The stress ratio significantly impacts the instability coefficient of faults with varying parameters.However,it has minimal effect on the overall distribution characteristics of the instability coefficient with the strike and dip angle under different stress regime.The fault parameters in the center of the high value area of the instability coefficient are determined by the specific stress field parameters and the friction coefficient.This study can provide reference for the study of the diversity of focal mechanism solutions,the uniformity of stress field,the friction strength and the pore pressure.
作者
盛书中
李振月
万永革
蒋长胜
王向腾
SHENG ShuZhong;LI ZhenYue;WAN YongGe;JIANG ChangSheng;WANG XiangTeng(School of Geophysics and Measurement-control Technology,East China University of Technology,Nanchang 330013,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Institute of Disaster Prevention,Sanhe Hebei 065201,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe Hebei 065201,China)
出处
《地球物理学报》
北大核心
2025年第11期4157-4168,共12页
Chinese Journal of Geophysics
基金
国家自然科学基金项目(42364005,42174074,41704053)
科技基础资源调查专项(2023FY201500)
东华理工大学博士科研启动基金(DHBK2019084)共同资助.
关键词
震源机制解
断层不稳定系数
应力莫尔圆
库仑-莫尔破裂准则
Focal mechanism
Fault instability coefficient
Mohr′s circle of stress
Mohr-Coulomb failure criterion
