关键词: 隐伏走滑断层, 模拟实验, 数字散斑相关方法, 破裂扩展

Abstract: It is important for active fault research and seismic hazard assessment in urban area to study the existence of buried active fault and its possible effect on the earth's surface.Many geophysical and geo～chemical techniques have been developed for exploration of buried active fault,and advanced remote techniques have been used in measurement and analysis of deformation on the earth's surface caused by earthquake on buried fault.However,the relationship between buried seismogenic fault and surface deformation and rupture caused by earthquake needs to be further studied.It is helpful for understanding rupture propagation along buried fault in loose sediment to study the evidence of fault sliding in the overlying sediments with simulation experiments.In this paper,rupture propagation along strike-slip fault in bed rock towards the overlying sediment layer has been studied with simulation experiment and deformation field on the surface of sediment layer has been observed using digital speckle correlation method,in which the effects of fault displacement and thickness of sediment layer were mainly analyzed.The research results indicate that a deformation and rupture zone composed of tension and shear fractures along the projection line of fault in bed rock is gradually formed in the sediments as the fault slips,given a constant thickness of the sediment layer.The larger the fault displacement is,the larger the width of deformation zone and the deformation intensity are.However,the width of deformation zone will keep constant when fault displacement exceeds a critical value,but the deformation will only become more concentrated as fault displacement increases.For a same fault displacement,the thicker the sediment layer is,the wider the deformation and rupture zone controlled by the bed rock fault will be,i.e.the larger the influencing extent of the fault is.However,when the sediment layer exceeds a critical thickness,the deformation pattern of sediment layer is changed.There exists no deformation zone consistent with the strike of fault in bed rock but a large-scale tensile shear rupture zone oblique to the fault strike.The experimental results imply that the critical fault displacement and the critical sediment thickness play important roles in determining the surface deformation and rupture caused by buried fault generated earthquake.

Key words: buried strike-slip fault, simulation experiment, digital speckle correlation method, fracture propagation