Intrinsic versus extrinsic seismic anisotropy: The radial anisotropy in reference Earth models
Intrinsic versus extrinsic seismic anisotropy: The radial anisotropy in reference Earth models
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内在与外在地震各向异性：参考地球模型中的径向各向异性
DOI：
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发表时间：
2013
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通讯作者：
Y. Capdeville
中科院分区：
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作者：
Nian Wang;J. Montagner;A. Fichtner;Y. Capdeville
地震各向异性通常由不同的机制引起，包括晶格或晶体学优选取向（LPO，CPO），有或没有流体包裹体的裂缝对齐，精细分层或部分熔融。这使得解释各向异性方面的“内在”（由LPO，CPO产生）与“外在”（由其他机制产生）的性质困难和非唯一的。一维全球球对称参考地球的径向各向异性通常被认为是内在的。在这里，我们将探讨包括初步参考地球模型（PREM）和约束参考地球模型ACY 400在内的一维参考地球模型中的径向各向异性是否包含外在各向异性，特别是与精细分层相关的径向各向异性。我们的结论是，以及内在的各向异性，外在的各向异性引入的精细分层模型，可以被认为是解释岩石圈各向异性在PREM，但不能单独解释其软流圈各向异性。我们还发现，在模型ACY 400的径向各向异性主要是由于其岩石学的限制，内在的。
Seismic anisotropy usually arises from different mechanisms, which include lattice or crystallographic preferred orientation (LPO, CPO), alignment of cracks with or without fluid inclusions, fine layering, or partial melting. This makes the interpretation of anisotropy in terms of “intrinsic” (produced by LPO, CPO) versus “extrinsic” (produced by other mechanisms) properties difficult and nonunique. The radial anisotropy in the one‐dimensional, global spherically symmetric reference Earth is usually claimed to be intrinsic. Here we explore whether the radial anisotropy in one‐dimensional reference Earth models including preliminary reference Earth model (PREM) and the constrained reference Earth model ACY400 contains extrinsic anisotropy, especially in relation to fine layering. We conclude that as well as intrinsic anisotropy, extrinsic anisotropy introduced by finely layered models, can be considered to explain the lithospheric anisotropy in PREM, but cannot explain alone its asthenospheric anisotropy. We also find that radial anisotropy in model ACY400 is mainly intrinsic due to its petrological constraints.