This study represents the first multistation investigation of azimuthal anisotropy beneath the interior of north central Africa, including Libya and adjacent regions, using shear wave splitting (SWS) analysis. Data used in the study include recently available broadband seismic data obtained from 15 stations managed by the Libyan Center for Remote Sensing and Space Science, and those from five other stations at which data are publicly accessible. A total of 583 pairs of high-quality SWS measurements utilizing the PKS, SKKS, and SKS phases demonstrate primarily N-S fast orientations with an average splitting delay time of approximately 1.2 s. An absence of periodic azimuthal variation of the observed splitting parameters indicates the presence of simple anisotropy, and lack of correlation between surficial features and the splitting parameters suggests that the origin of the observed anisotropy is primarily asthenospheric. This conclusion is enhanced by nonperiodic azimuthal variation of the splitting parameters observed at one of the stations located near the boundary of areas with different anisotropic properties. We interpret the observed anisotropy to be the consequence of northward movement of the African plate relative to the asthenosphere toward the Hellenic and Calabrian subduction zones. Local variance in fast orientations may be attributable to flow deflection by the northern edge of the African continental root. The observations provide critical and previously lacking constraints on mantle dynamic models in the vicinity of the convergent boundary between the African and Eurasian plates.
A. A. Lemnifi et al., "Azimuthal Anisotropy beneath North Central Africa from Shear Wave Splitting Analyses," Geochemistry, Geophysics, Geosystems, vol. 16, no. 4, pp. 1105-1114, John Wiley & Sons Ltd, Apr 2015.
The definitive version is available at https://doi.org/10.1002/2014GC005706
Geosciences and Geological and Petroleum Engineering
Center for High Performance Computing Research
Keywords and Phrases
Anisotropy; Remote Sensing; Seismology; Shear Flow; Slow Wave Structures; Anisotropic Property; Azimuthal Anisotropy; Azimuthal Variations; Mantle Flow; Publicly Accessible; Seismic Anisotropy; Shear Wave Splitting; Subduction Zones; Shear Waves; Asthenosphere; Azimuth; Body Wave; Mantle Process; S-Wave; Seismic Anisotropy; Seismic Data; Wave Splitting; Libyan Arab Jamahiriya; North Africa
International Standard Serial Number (ISSN)
Article - Journal
© 2015 John Wiley & Sons Ltd, All rights reserved.