Abstract

Abstract : Seismic refraction measurements of the compressional wave velocity of the upper mantle, obtained in the northeast Pacific Ocean between California and Hawaii, have shown a dependence on direction indicating anisotropy of velocity with a maximum of 8.6 km/sec in a roughly easterly direction and a minimum of 8.9 km/sec. In order to test whether or not these observations represent true anisotropy, rather than geographical variation of velocity, special anisotropy experiments were conducted at two locations centered roughly at 31 degrees N, 121 degrees W and 35 degrees N, 126 degrees W respectively. At each of these locations significant anisotropy was observed, agreeing in direction with the apparent anisotropy indicated for the entire region. The magnitude of the velocity difference, 0.3 km/sec, is half of the overall variation of 0.6 km/sec. These observations do not prove the hypothesis of anisotropy throughout the entire region from California to Hawaii. However, they are consistent with this hypothesis, and give encouragement to similar observations elsewhere. (Author)

Keywords

AnisotropyGeologyGeophysicsMantle (geology)Seismic anisotropyPhysics

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Publication Info

Year
1969
Type
article
Volume
74
Issue
12
Pages
3095-3109
Citations
444
Access
Closed

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Cite This

Russell W. Raitt, George G. Shor, T. J. G. Francis et al. (1969). Anisotropy of the Pacific upper mantle. Journal of Geophysical Research Atmospheres , 74 (12) , 3095-3109. https://doi.org/10.1029/jb074i012p03095

Identifiers

DOI
10.1029/jb074i012p03095