Empirical assessment of the validity limits of the surface wave full ray theory using realistic 3-D Earth models

Handle URI:
http://hdl.handle.net/10754/600707
Title:
Empirical assessment of the validity limits of the surface wave full ray theory using realistic 3-D Earth models
Authors:
Parisi, Laura; Ferreira, Ana M.G.
Abstract:
The surface wave full ray theory (FRT) is an efficient tool to calculate synthetic waveforms of surface waves. It combines the concept of local modes with exact ray tracing as a function of frequency, providing a more complete description of surface wave propagation than the widely used great circle approximation (GCA). The purpose of this study is to evaluate the ability of the FRT approach to model teleseismic long-period surface waveforms (T ∼ 45–150 s) in the context of current 3-D Earth models to empirically assess its validity domain and its scope for future studies in seismic tomography. To achieve this goal, we compute vertical and horizontal component fundamental mode synthetic Rayleigh waveforms using the FRT, which are compared with calculations using the highly accurate spectral element method. We use 13 global earth models including 3-D crustal and mantle structure, which are derived by successively varying the strength and lengthscale of heterogeneity in current tomographic models. For completeness, GCA waveforms are also compared with the spectral element method. We find that the FRT accurately predicts the phase and amplitude of long-period Rayleigh waves (T ∼ 45–150 s) for almost all the models considered, with errors in the modelling of the phase (amplitude) of Rayleigh waves being smaller than 5 per cent (10 per cent) in most cases. The largest errors in phase and amplitude are observed for T ∼ 45 s and for the three roughest earth models considered that exhibit shear wave anomalies of up to ∼20 per cent, which is much larger than in current global tomographic models. In addition, we find that overall the GCA does not predict Rayleigh wave amplitudes well, except for the longest wave periods (T ∼ 150 s) and the smoothest models considered. Although the GCA accurately predicts Rayleigh wave phase for current earth models such as S20RTS and S40RTS, FRT's phase errors are smaller, notably for the shortest wave periods considered (T ∼ 45 s and T ∼ 60 s). This suggests that the FRT approach is a useful means to build the next generation of elastic and anelastic surface wave tomography models. Finally, we observe a clear correlation between the FRT amplitude and phase errors and the roughness of the models. This allows us to quantify the limits of validity of the FRT in terms of model roughness thresholds, which can serve as useful guides in future seismic tomographic studies.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Citation:
Empirical assessment of the validity limits of the surface wave full ray theory using realistic 3-D Earth models 2016, 205 (1):146 Geophysical Journal International
Publisher:
Oxford University Press (OUP)
Journal:
Geophysical Journal International
Issue Date:
10-Feb-2016
DOI:
10.1093/gji/ggw005
Type:
Article
ISSN:
0956-540X; 1365-246X
Sponsors:
We sincerely thank Eric Debayle, an anonymous reviewer and the editor Andrea Morelli for their detailed reviews, which helped improve our manuscript. This research was carried out on the High Performance Computing Cluster supported by the Research and Specialist Computing Support services at the University of East Anglia and on Archer, the UK's National Supercomputing Service. Some figures were built using Generic Mapping Tools (GMT; Wessel & Smith 1998). This work was supported by the European Commission's Initial Training Network project QUEST (contract FP7-PEOPLE-ITN-2008-238007, http://www.quest-itn.org) and the University of East Anglia. The Incorporated Research Institutions for Seismology (IRIS) was used to access the waveform data from the IRIS/IDA network II (http://dx.doi.org/doi:10.7914/SN/II) and IU (http://dx.doi.org/doi:10.7914/SN/IU). AMGF also thanks funding by the Fundacao para a Ciencia e Tecnologia (FCT) project AQUAREL (PTDC/CTE-GIX/116819/2010).
Additional Links:
http://gji.oxfordjournals.org/lookup/doi/10.1093/gji/ggw005
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorParisi, Lauraen
dc.contributor.authorFerreira, Ana M.G.en
dc.date.accessioned2016-03-07T13:11:03Zen
dc.date.available2016-03-07T13:11:03Zen
dc.date.issued2016-02-10en
dc.identifier.citationEmpirical assessment of the validity limits of the surface wave full ray theory using realistic 3-D Earth models 2016, 205 (1):146 Geophysical Journal Internationalen
dc.identifier.issn0956-540Xen
dc.identifier.issn1365-246Xen
dc.identifier.doi10.1093/gji/ggw005en
dc.identifier.urihttp://hdl.handle.net/10754/600707en
dc.description.abstractThe surface wave full ray theory (FRT) is an efficient tool to calculate synthetic waveforms of surface waves. It combines the concept of local modes with exact ray tracing as a function of frequency, providing a more complete description of surface wave propagation than the widely used great circle approximation (GCA). The purpose of this study is to evaluate the ability of the FRT approach to model teleseismic long-period surface waveforms (T ∼ 45–150 s) in the context of current 3-D Earth models to empirically assess its validity domain and its scope for future studies in seismic tomography. To achieve this goal, we compute vertical and horizontal component fundamental mode synthetic Rayleigh waveforms using the FRT, which are compared with calculations using the highly accurate spectral element method. We use 13 global earth models including 3-D crustal and mantle structure, which are derived by successively varying the strength and lengthscale of heterogeneity in current tomographic models. For completeness, GCA waveforms are also compared with the spectral element method. We find that the FRT accurately predicts the phase and amplitude of long-period Rayleigh waves (T ∼ 45–150 s) for almost all the models considered, with errors in the modelling of the phase (amplitude) of Rayleigh waves being smaller than 5 per cent (10 per cent) in most cases. The largest errors in phase and amplitude are observed for T ∼ 45 s and for the three roughest earth models considered that exhibit shear wave anomalies of up to ∼20 per cent, which is much larger than in current global tomographic models. In addition, we find that overall the GCA does not predict Rayleigh wave amplitudes well, except for the longest wave periods (T ∼ 150 s) and the smoothest models considered. Although the GCA accurately predicts Rayleigh wave phase for current earth models such as S20RTS and S40RTS, FRT's phase errors are smaller, notably for the shortest wave periods considered (T ∼ 45 s and T ∼ 60 s). This suggests that the FRT approach is a useful means to build the next generation of elastic and anelastic surface wave tomography models. Finally, we observe a clear correlation between the FRT amplitude and phase errors and the roughness of the models. This allows us to quantify the limits of validity of the FRT in terms of model roughness thresholds, which can serve as useful guides in future seismic tomographic studies.en
dc.description.sponsorshipWe sincerely thank Eric Debayle, an anonymous reviewer and the editor Andrea Morelli for their detailed reviews, which helped improve our manuscript. This research was carried out on the High Performance Computing Cluster supported by the Research and Specialist Computing Support services at the University of East Anglia and on Archer, the UK's National Supercomputing Service. Some figures were built using Generic Mapping Tools (GMT; Wessel & Smith 1998). This work was supported by the European Commission's Initial Training Network project QUEST (contract FP7-PEOPLE-ITN-2008-238007, http://www.quest-itn.org) and the University of East Anglia. The Incorporated Research Institutions for Seismology (IRIS) was used to access the waveform data from the IRIS/IDA network II (http://dx.doi.org/doi:10.7914/SN/II) and IU (http://dx.doi.org/doi:10.7914/SN/IU). AMGF also thanks funding by the Fundacao para a Ciencia e Tecnologia (FCT) project AQUAREL (PTDC/CTE-GIX/116819/2010).en
dc.language.isoenen
dc.publisherOxford University Press (OUP)en
dc.relation.urlhttp://gji.oxfordjournals.org/lookup/doi/10.1093/gji/ggw005en
dc.rightsThis article has been accepted for publication in Geophysical Journal International ©The Authors 2016. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.en
dc.subjectSurface waves and free oscillationsen
dc.subjectSeismic tomographyen
dc.subjectComputational seismologyen
dc.subjectWave propagationen
dc.titleEmpirical assessment of the validity limits of the surface wave full ray theory using realistic 3-D Earth modelsen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalGeophysical Journal Internationalen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionSchool of Environmental Sciences, University of East Anglia, Norwich, United Kingdomen
dc.contributor.institutionDepartment of Earth Sciences, University College of London, London, United Kingdomen
dc.contributor.institutionCEris, ICIST, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugalen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorParisi, Lauraen
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