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DOI	10.5194/tc-10-3063-2016
	Critical investigation of calculation methods for the elastic velocities in anisotropic ice polycrystals
	Maurel A.; Mercier J.-F.; Montagnat M.
发表日期	2016
ISSN	19940416
卷号	10 期号:6
英文摘要	Crystallographic texture (or fabric) evolution with depth along ice cores can be evaluated using borehole sonic logging measurements. These measurements provide the velocities of elastic waves that depend on the ice polycrystal anisotropy, and they can further be related to the ice texture. To do so, elastic velocities need to be inverted from a modeling approach that relate elastic velocities to ice texture. So far, two different approaches can be found. A classical model is based on the effective medium theory; the velocities are derived from elastic wave propagation in a homogeneous medium characterized by an average elasticity tensor. Alternatively, a velocity averaging approach was used in the glaciology community that averages the velocities from a given population of single crystals with different orientations. In this paper, we show that the velocity averaging method is erroneous in the present context. This is demonstrated for the case of waves propagating along the clustering direction of a highly textured polycrystal, characterized by crystallographic c axes oriented along a single maximum (cluster). In this case, two different shear wave velocities are obtained while a unique velocity is theoretically expected. While making use of this velocity averaging method, reference work by Bennett (1968) does not end with such an unphysical result. We show that this is due to the use of erroneous expressions for the shear wave velocities in a single crystal, as the starting point of the averaging process. Because of the weak elastic anisotropy of ice single crystal, the inversion of the measured velocities requires accurate modeling approaches. We demonstrate here that the inversion method based on the effective medium theory provides physically based results and should therefore be favored. © Author(s) 2016.
学科领域	anisotropy; borehole logging; elastic wave; elasticity; glaciology; homogeneous medium; ice crystal; moment tensor; S-wave; texture; wave propagation; wave velocity
语种	英语
scopus关键词	anisotropy; borehole logging; elastic wave; elasticity; glaciology; homogeneous medium; ice crystal; moment tensor; S-wave; texture; wave propagation; wave velocity
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119527
作者单位	Institut Langevin, CNRS, ESPCI ParisTech, 1 rue Jussieu, Paris, 75005, France; Poems, CNRS, ENSTA ParisTech, INRIA, 828 boulevard des Maréchaux, Palaiseau, 91762, France; LGGE, CNRS, Université Grenoble Alpes, Grenoble, 38041, France
推荐引用方式 GB/T 7714	Maurel A.,Mercier J.-F.,Montagnat M.. Critical investigation of calculation methods for the elastic velocities in anisotropic ice polycrystals[J],2016,10(6).
APA	Maurel A.,Mercier J.-F.,&Montagnat M..(2016).Critical investigation of calculation methods for the elastic velocities in anisotropic ice polycrystals.Cryosphere,10(6).
MLA	Maurel A.,et al."Critical investigation of calculation methods for the elastic velocities in anisotropic ice polycrystals".Cryosphere 10.6(2016).