摘要
断层的自发破裂及其产生的地震波场是地震学研究的重要内容.断层几何形态和自发破裂过程中的动力学参数不同,往往会导致不同的震源破裂过程,进而对地震波场产生显著的影响.本文基于不同几何形态的断层上的自发破裂过程,通过计算研究其产生的地震波场的特征.针对弯折和分叉的断层系统,我们考察了初始成核区位置以及超剪切破裂对于地震波场的影响.结果显示,对于弯折断层,随着弯折角的增大,地震波场的峰值分布沿着弯折方向产生变化,过大的弯折角会对地震波场起抑制作用;在断层上破裂距离越长,积累的能量越大,引起的地震波场峰值也越大.对于分叉断层,角度更小的分支面具有更大的破裂优势,破裂强度更大,会引起更大的地震波场峰值.超剪切破裂将使得地震波场振幅更大,激发高频成分,在波形上能观察到明显的脉冲,同时增大永久位移.通过研究动力学破裂产生的地震波场的行为,有助于增进对地震波场特征产生原因的认识,为进一步的动力学参数反演奠定了基础.
The spontaneous rupture of faults and its resulting seismic wave field are important subject in seismological research.Different fault geometry and dynamic parameters in the spontaneous rupture process often lead to different rupture processes,which in turn have a significant impact on the seismic wave field.In this work,we computed the spontaneous rupture process on faults with different geometries,and analyzed the characteristics of the corresponding seismic wave field.Two kinds of fault systems which are bending and branching faults are considered.We investigated the impact of the position of the initial nucleation zone and supershear rupture on the seismic wave field for each system separately.The results show that for bending faults,as the bending angle increases,the peak distribution of the seismic wave field changes along the bending direction.Excessive bending angles will depress the seismic wave field.The longer the rupture distance on the faults is,the more energy will be accumulated,which will cause a larger seismic wave field.For branching faults,the branch plane with a smaller angle is more likely to rupture,and the rupture strength is greater,which will cause a stronger seismic wave field.The supershear rupture will also cause a stronger seismic wave field and excite high-frequency components.Obvious pulses can be observed and the permanent displacement will be increased.The results of this study is helpful to understand seismic wave field characteristics and provide more information for further dynamics inversion.
作者
吴永祺
张海明
WU YongQi;ZHANG HaiMing(Department of Geophysics,School of Earth and Space Sciences,Peking University,Beijing 100871,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第3期965-977,共13页
Chinese Journal of Geophysics
基金
国家重点研发计划(2020YFA0710600)
国家自然科学基金项目(41874070)资助。
关键词
地震波场
动态破裂
边界积分方程
弯折断层
分叉断层
Seismic wave field
Dynamic rupture
Boundary integral equation
Bending fault
Branching fault
