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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The influence of shear-velocity heterogeneity on ScS2/ScS amplitude ratios and estimates of Q in the mantle

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Author(s):
Chaves, Carlos A. M. ; Ritsema, Jeroen
Total Authors: 2
Document type: Journal article
Source: Geophysical Research Letters; v. 43, n. 15, p. 7997-8005, AUG 16 2016.
Web of Science Citations: 2
Abstract

Regional waveforms of deep-focus Tonga-Fiji earthquakes indicate anomalous traveltime differences (ScS2-ScS) and amplitude ratios (ScS2/ScS) of the phases ScS and ScS2. The correlation between the ScS2-ScS delay time and the ScS2/ScS amplitude ratio suggests that shear wave apparent Q in the mantle below the Tonga-Fiji region is highest when shear wave velocities are lowest. This observation is unexpected if temperature variations were responsible for the seismic anomalies. Using spectral element method waveform simulations for four tomographic models, we demonstrate that focusing and scattering of shear waves by long-wavelength 3-D heterogeneity in the mantle may overwhelm the signal from intrinsic attenuation in long-period ScS2/ScS amplitude ratios. The tomographic models reproduce the trends in recorded ScS2-ScS difference times and ScS2/ScS amplitude ratios. Although they cannot be ruled out, variations in shear wave attenuation (i.e., the quality factor Q) are not necessary to explain the data. (AU)

FAPESP's process: 14/17779-3 - Global study of the mantle transition zone structure from geoid anomalies and SS wave propagation
Grantee:Carlos Alberto Moreno Chaves
Support type: Scholarships in Brazil - Post-Doctorate