平移断层的倾角对地震产生的影响
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摘要
利用边界单元法和滑移弱化摩擦本构关系分析了平移断层上地震的产生。从依赖于速率和状态的摩擦本构关系出发,通过忽略速度的影响得到了滑移弱化摩擦本构关系。建立了两种本构关系之间的联系,使得在两种模型中可以使用共同的参数。通过将地球表面模拟成一个包含在无穷大弹性介质中的无穷大裂纹,已有的边界积分方法可以直接用来分析断层的滑移。由于断层上的摩擦本构关系的非线性,得到的方程也是非线性的,采用牛顿迭代法进行求解。通过数值计算得到了平移断层上滑移位移、速度及摩擦力的分布规律。考察了平移断层的倾角对地震产生的影响,计算结果表明断层的倾角越小,地震产生的位置离地球表面越近且地震产生所需滑移的时间越短。
Earthquake nucleation with strike slip fault was analyzed by means of the variational boundary integral method and slip weakening friction law. The slip weakening friction law was derived from the rate and state dependent friction law by neglecting the velocity effects. This bridges some relationships between theses two kinds of friction law and it is possible to use the common parameters in two kinds of models. By modeling the earth surface as an infinite crake embedded in the infinite medium, the previous variational boundary integral method can be extended to analyze the fault slip. The discretized nonlinear equations by virtue of non-linear friction law were solved by Newton-Raphson iteration. The distribution of slip displacement, slip velocity and friction force on the strike slip fault were obtained by numerical simulation. The effects of dip angle on the earthquake nucleation were presented. The results show that the location of earthquake nucleation is more close to the ground surface and the time of earthquake nucleation is shorter for the fault of smaller dip angle.
Earthquake nucleation with strike slip fault was analyzed by means of the variational boundary integral method and slip weakening friction law. The slip weakening friction law was derived from the rate and state dependent friction law by neglecting the velocity effects. This bridges some relationships between theses two kinds of friction law and it is possible to use the common parameters in two kinds of models. By modeling the earth surface as an infinite crake embedded in the infinite medium, the previous variational boundary integral method can be extended to analyze the fault slip. The discretized nonlinear equations by virtue of non-linear friction law were solved by Newton-Raphson iteration. The distribution of slip displacement, slip velocity and friction force on the strike slip fault were obtained by numerical simulation. The effects of dip angle on the earthquake nucleation were presented. The results show that the location of earthquake nucleation is more close to the ground surface and the time of earthquake nucleation is shorter for the fault of smaller dip angle.
引文
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[7] OhnakeM,YamashitaT.A cohesive zone model for dynamic shear faulting based on experimentally inferred constitutive relation andstrong motion source parameters[J].J GeophysRes,1989,94:40984104.
[8] BizzarriA,CoccoM,AndrewsD J,BoshiE.Solving the dynamic rupture problem with different numerical approaches and constitutivelaws[J].GeophysJ Int,2001,144:656678.
[9] ZhangC,OglesbyD D,XuG.Earthquake nucleation on dip slip faults[J].J GeophysRes, in press,2004,109:B11302.
[10] XuG,ArgonA S,OrtizM.Nucleation of dislocations from crack tips under mixed modes of loading: implications for brittle against duc tile behaviour of crystals[J].PhilosophicalMagazineA,1995,72(2):415451.
[2] OhnakaM,ShenL F.Scaling of the shear rupture process from nucleation to dynamic propagation:Implications of geometric irregulari ty of the rupturing surfaces[J].Journal ofGeophysicalResearch,1999,104(B1):817844.
[3] IdaY.Cohesive force across the tip of a longitudinal shear crack andGriffith s specific surface energy[J].Journal ofGeophysicalRe search,1972,77:37963805.
[4] RuinaA L.Slip instability and state varaible friction laws[J].Journal ofGeophysicalResearch,1983,88:1035910370.
[5] RiceJ R.Spatio temporal complexity of slip on a fault[J].J GeophysRes,1993,98:98859907.
[6] ChinneryM.The stress changes that accompany strike slip faulting[J].BullSeismolSocAm,1963,53:921932.
[7] OhnakeM,YamashitaT.A cohesive zone model for dynamic shear faulting based on experimentally inferred constitutive relation andstrong motion source parameters[J].J GeophysRes,1989,94:40984104.
[8] BizzarriA,CoccoM,AndrewsD J,BoshiE.Solving the dynamic rupture problem with different numerical approaches and constitutivelaws[J].GeophysJ Int,2001,144:656678.
[9] ZhangC,OglesbyD D,XuG.Earthquake nucleation on dip slip faults[J].J GeophysRes, in press,2004,109:B11302.
[10] XuG,ArgonA S,OrtizM.Nucleation of dislocations from crack tips under mixed modes of loading: implications for brittle against duc tile behaviour of crystals[J].PhilosophicalMagazineA,1995,72(2):415451.
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