近场强地震动断层面不均匀位错预测模型

摘要

断层破裂面不均匀位错空间分布会强烈影响近场强地震动强度及频谱特性。为描述断层破裂面位错不均匀性，设断层子源划分与地震矩无关，采用分形法划分子源，避免子源相互重叠或覆盖；设应力降不为常数修正自相似模型，获得子源断层位错与整体断层位错关系，改进已有凹凸体模型。以美国北岭地震为例，预测断层破裂面位错不均匀性，对比震后反演情况，验证预测模型的有效性。%The space distribution of inhomogeneous dislocation on the fault fracture surface has strong influence on the strength and spatial variation of the near-field strong ground motion.The parameters of a finite faults source model were divided into global source parameters and local source parameters.The global source parameters describe the macro feature of the fault,and the local source parameters describe the inhomogeneous distribution of dislocation on the fault fracture surface.In order to describe the inhomogeneous distribution of the fault,the fault subevents division was assumed to be with no relation to the seismic moments and the fractal method was used to delimit the subevents to avoid overlapping or covering.The stress drop was assumed to be not constant to modify the self-similar model and the relation between subevents and fault was achieved to improve the existing asperity model.Taking the Northridge earthquake as an example, the inhomogeneous distribution of the fault was predicted to verify the validity of the prediction model.