| Summary: | 碩士 === 國立中正大學 === 地震研究所暨應用地球物理研究所 === 97 === This research is uses the normal mode summation method ( Capdeville, 2005) analysis the phase velocity dispersion data of Rayleigh wave, obtains under the different periods correspond the depth the shear wave velocity structure, and using Debayle and Sambridge (2004) develops the inversion shear velocity structure and the anisotropic research, the shear velocity of the crust and upper mantle beneath of the Philippine Sea Plate, and obtains the anisotropic lateral variation.
This findings obtain, the shallow structure of Philippine Sea Plate, as a result of surface complex geologic structure, therefore has the obvious velocity lateral variation. But place has thermal column material which in Amami Plate, Oki Daito Ridge, Daito the Ridge existence the magmatic activity remained in the past, therefore had compares the low velocity the distribution. When the depth arrives at upper mantle, north part of the Philippine Sea Plate connected the Pacific Ocean Plate, the Philippine Sea Plate and the Eurasian Plate , has the obvious low velocity area. Both sides have a symmetrical high velocity belt in Daito the Ridge, possibly is the deposit which the early time tectonism remains. When the depth arrives at 111 kilometers and 150 kilometers, the Philippine Sea Plate should for the asthenosphere scope.
The anisotropic result obtains, west-south the Philippine basin''s quick wave direction mostly approaches east-west direction, with the earth stress approximately parallel. The Ryukyu Trench、the Nankai Trough anisotropic direction approximately for northwest - southeast approaches, related crust crack arrangement. West Philippine Basin anisotropic direction is obvious, for northeast - southwest, is consistent with the basin expansion direction. Anisotropic direction of Shikoku Basin and the Parece Vela Basin, for northeast-southwest, concerns with the basin tension crack''s direction.
|
|---|
