The topological nature of the polarization field for body waves in anisotropic elastic media

1980 ◽  
Vol 370 (1742) ◽  
pp. 331-350 ◽  
Keyword(s):  
Eigenvalue Problem ◽  
Sound Wave ◽  
Body Waves ◽  
Polarization Field ◽  
Elastic Media ◽  
Wave Polarization ◽  
Different Types ◽  
Anisotropic Elastic ◽  
Elastic Crystals

Topologically, two different types of sound wave polarization fields are possible in elastic crystals without acoustic axes. It is shown that only one type occurs. Usually, however, acoustic axes are present. The relation between the Khatkevich condition for acoustic axes and the discriminant of the eigenvalue problem is elucidated.

scholarly journals Rotational motions in homogeneous anisotropic elastic media

Geophysics ◽  
2010 ◽  
Vol 75 (5) ◽  
pp. D47-D56 ◽  
Author(s):  
Nguyen Dinh Pham ◽  
Heiner Igel ◽  
Josep de la Puente ◽  
Martin Käser ◽  
Michael A. Schoenberg
Keyword(s):  
Rotational Energy ◽  
Propagation Direction ◽  
Body Waves ◽  
Elastic Media ◽  
P Waves ◽  
Rotation Rates ◽  
Isotropic Media ◽  
Christoffel Equation ◽  
Rotational Motions ◽  
Anisotropic Elastic

Rotational motions in homogeneous anisotropic elastic media are studied under the assumption of plane wave propagation. The main goal is to investigate the influences of anisotropy in the behavior of the rotational wavefield. The focus is on P-waves that theoretically do not generate rotational motion in isotropic media. By using the Kelvin–Christoffel equation, expressions are obtained of the rotational motions of body waves as a function of the propagation direction and the coefficients of the elastic modulus matrix. As a result, the amplitudes of the rotation rates and their radiation patterns are quantified and it is concluded that (1) for strong local earthquakes and typical reservoir situations quasi P-rotation rates induced by anisotropy are significant, recordable, and can be used for inverse problems; and (2) for teleseismic wavefields, anisotropic effects are unlikely to be responsible for the observed rotational energy in the P coda.

Weak-contrast edge and vertex diffractions in anisotropic elastic media

Wave Motion ◽  
1999 ◽  
Vol 29 (4) ◽  
pp. 363-373 ◽  
Author(s):  
Martin Tygel ◽  
Bjørn Ursin
Keyword(s):  
Elastic Media ◽  
Anisotropic Elastic

Coefficient identification for cubically anisotropic elastic media

2015 ◽  
Vol 24 (4) ◽  
pp. 567-582
Author(s):  
Meltem Altunkaynak ◽  
Paul Sacks ◽  
Valery G. Yakhno
Keyword(s):  
Elastic Media ◽  
Coefficient Identification ◽  
Anisotropic Elastic
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