横向非均匀介质远震体波接收函数的波场特征

系统研究了台站下方存在倾斜界面时，远震体波接收函数的波场特征及多方位接收函数对台站下方介质横向非均匀特征的反映能力．我们利用合成三维横向非均匀介质接收函数的Maslov方法，具体模拟了台站下方存在倾斜界面时的接收函数响应．结果表明，当台站下方存在倾向一致的倾斜界面时，远震体波接收函数的径向分量和切向分量分别随震源方位角的变化呈现对称和反对称的规律性变化．利用不同震源方位角接收函数径向分量和切向分量的变化规律，可以估计台站下方界面的倾向和倾角．当台站下方各界面的倾向不同时，随方位角的变化，接收函数只能直观给出界面的整体倾向．实际观测数据的分析结果表明，对于利用单个台站接收函数研究台站下方介质的横向非均匀特征来说，简单倾斜界面可以看作较好的一级近似．

WAVEFIELD FEATURES OF TELESEISMIC RECEIVER FUNCTION IN LATERALLY INHOMOGENEOUS MEDIA

WT5BZ]In this study we systemically investigate the effects of laterally inhomogeneous crustal structure with planar dipping interfaces on the teleseismic receiver function. For this purpose, the Maslov asymptotic ray theory of the receiver functions in the 3 D laterally inhomogeneous media (Chen and Liu, 1999) is used for computing the synthetic receiver functions, when dipping interfaces exist under a single station. Our results demonstrate that the symmetric and asymmetric variations above the incident azimuths appear on the radial and transverse components of the receiver function, respectively. The dipping direction and dipping angle of the interface beneath the station can be estimated from these features. But, when several different dipping interfaces exist within the crust, only an apparent dipping direction can be inferred from the waveform variations of the receiver function over different azimuths at a single station. By analyzing our observational data it is shown that the planar dipping interface is a well first order approximation for investigating the crustal lateral inhomogeneity, when only data recorded at a single station are used. And our results given in this study are consistent with those given by seismic array study.