太平洋盆地勒夫波与瑞利波不一致性的研究

在勒夫波及瑞利波频散反演的基础上,本文分析了太平洋盆地水平剪切波速度SH与垂直剪切波速度SV之间的不一致性,并对其成因及与地球各向异性之间的关系进行了探讨。我们发现:除最顶部一二十公里处的SH小于SV之外,在几乎整个太平洋岩石圈内,SH都大于SV。此外,在占太平洋大约2/3的区域下面的软流圈内,SH略高于SV。如此广泛存在的SH与SV的不一致性可能是与大规模地质及构造过程有关的太平洋地壳及上地幔的固有各向异性的一个证据。

STUDY ON THE LOVE WAVE/RAYLEIGH WAVE INCOMPATIBILITY IN THE PACIFIC OCEAN BASIN

In this paper the incompatibility of the horizontal shear wave velocity SH with the vertical shear wave velocity SV in the Pacific ocean basin was investigated based on the Love and Rayleigh-wave dispersion inversions. The possible cause of the incompatibility and its relationship to the anisotropy in the Earth were also explored. It is found that SH velocity is greater than SV velocity in almost the entire Pacific lithosphere except for the topmost ten or twenty kilometers where SH velocity is less than SV velocity. In the asthenosphere it is also found that SH velocity is slightly higher than SV velocity for about two thirds of the Pacific. Such broadly existing "Love wave/Rayleigh wave incompatibility" may be an evidence of the intrinsic anisotropy in the Pacific crust and upper mantle associated with the large scale geological and tectonic processes.