断层面位错不均匀性对地表同震变形的影响研究

Study on the influence of dislocation unevenness of fault plane on ground co-seismic deformation

对断层面上的位错分布情况进行探讨,基于凹凸体震源模型提出一种考虑断层面上位错不均匀性的新型位错分布模式。该模式基于Somerville理论和经验公式对断层面上的凹凸体分布进行划分,以分析断层错动导致的同震位移场影响。通过求解凹凸体位错分布模式下的同震变形得出地表位移场随凹凸体位置的变化特征,并以1989年Mw6.95级Loma Prieta地震为例,将凹凸体位错分布模式的计算结果与均匀分布和真实分布进行对比,验证了凹凸体分布模式的合理性。最后对不同断层类型下位错分布模式的地表同震变形影响进行分析,揭示了均匀位错分布模式的不足,研究结果可为活动断层危害性评价提供指导。

In this paper,the distribution of dislocations on the fault plane is discussed,and a new type of dislocation distribution mode,taking into account the unevenness of the dislocations on the fault plane,is proposed based on the asperity model.This model is based on Somerville theory and empirical formulas to divide the distribution of asperity on the fault plane and to analyze the influence of fault dislocation on the co-seismic deformation.By solving the co-seismic deformation in the asperity dislocation distribution mode,the variation characteristics of the surface displacement field with the asperity position were obtained.Taking the Mw6.95 Loma Prieta earthquake in 1989 as an example,the calculation results of the asperity dislocation distribution mode were compared with the uniform distribution and the real distribution to verify the accuracy of the asperity distribution mode.Finally,the effect of dislocation distribution mode on the surface co-seismic deformation under different fault types is analyzed,which reveals the shortcomings of the uniform dislocation distribution mode.The research results can provide a guidance for the risk assessment of active faults.