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Finite-frequency effects in global surface-wave tomography

Zhou, Ying and Dahlen, F. A. and Nolet, Guust and Laske, Gabi (2005) Finite-frequency effects in global surface-wave tomography. Geophysical Journal International, 163 (3). pp. 1087-1111. ISSN 0956-540X. https://resolver.caltech.edu/CaltechAUTHORS:20171205-081910147

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Abstract

We compare traditional ray-theoretical surface-wave tomography with finite-frequency tomography, using 3-D Born sensitivity kernels for long-period, fundamental-mode dispersion measurements. The 3-D kernels preserve sidelobes beyond the first Fresnel zone, and fully account for the directional dependence of surface-wave scattering, and the effects of time-domain tapering and seismic source radiation. Tomographic inversions of Love and Rayleigh phase-delay measurements and synthetic checkerboard tests show that (1) small-scale S-wave velocity anomalies are better resolved using finite-frequency sensitivity kernels, especially in the lowermost upper mantle; (2) the resulting upper-mantle heterogeneities are generally stronger in amplitude than those recovered using ray theory and (3) finite-frequency tomographic models fit long-period dispersion data better than ray-theoretical models of comparable roughness. We also examine the reliability of 2-D, phase-velocity sensitivity kernels in global surface-wave tomography, and show that phase-velocity kernels based upon a forward-scattering approximation or previously adopted geometrical simplifications do not reliably account for finite-frequency wave-propagation effects. 3-D sensitivity kernels with full consideration of directional-dependent seismic scattering are the preferred method of inverting long-period dispersion data. Finally, we derive 2-D boundary sensitivity kernels for lateral variations in crustal thickness, and show that finite-frequency crustal effects are not negligible in long-period surface-wave dispersion studies, especially for paths along continent-ocean boundaries. Unfortunately, we also show that, in global studies, linear perturbation theory is not sufficiently accurate to make reliable crustal corrections, due to the large difference in thickness between oceanic and continental crust.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1111/j.1365-246X.2005.02780.xDOIArticle
https://academic.oup.com/gji/article/163/3/1087/594817PublisherArticle
Additional Information:© 2005 RAS. Accepted 2005 August 8. Received 2005 June 22; in original form 2004 December 30. Published: 01 December 2005. We thank the two reviewers, Jeroen Tromp and Jeannot Trampert, for their thoughtful and constructive comments. We also thank IDA, USGS, GEOSCOPE and IRIS for collecting and distributing seismic data. This research was financially supported by the US National Science Foundation under Grants EAR-0105387 and EAR-0309298. All maps were generated using the Generic Mapping Tools (GMT) (Wessel & Smith 1995).
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-0105387
NSFEAR-0309298
Subject Keywords:Fréchet derivatives, global seismology, sensitivity, surface waves, tomography
Issue or Number:3
Record Number:CaltechAUTHORS:20171205-081910147
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20171205-081910147
Official Citation:Ying Zhou, F. A. Dahlen, Guust Nolet, Gabi Laske; Finite-frequency effects in global surface-wave tomography, Geophysical Journal International, Volume 163, Issue 3, 1 December 2005, Pages 1087–1111, https://doi.org/10.1111/j.1365-246X.2005.02780.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83685
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Dec 2017 05:07
Last Modified:03 Oct 2019 19:09

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