Are we exceeding the limits of the Great Circle Approximation in global surface wave tomography?

Spetzler, Jesper; Trampert, Jeannot; Snieder, Roel

doi:10.1029/2000gl012691

Cited by 33 publications

(36 citation statements)

References 24 publications

(12 reference statements)

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“…It remains unclear to what extent this limit can be outdone through the application of finite-frequency methods (Li and Romanowicz 1996;Dahlen et al 2000;Spetzler et al 2001;Zhou et al 2006). Peter et al (2008) compared ray-theoretical and finite-frequency tomographies based on the Rayleigh-wave component of our database.…”

Section: The Ray-theory Limitmentioning

confidence: 99%

The European Upper Mantle as Seen by Surface Waves

Boschi¹,

Fry²,

Ekström³

et al. 2009

Arrays and Array Methods in Global Seismology

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We derive a global, three-dimensional tomographic model of horizontally and vertically polarized shear velocities in the upper mantle. The model is based on a recently updated global database of Love-and Rayleigh-wave fundamental-mode phase-anomaly observations, with a good global coverage and a particularly dense coverage over Europe and the Mediterranean basin (broadband stations from the Swiss and German seismic networks). The model parameterization is accordingly finer within this region than over the rest of the globe. The large-scale, global structure of our model is very well correlated with that of earlier shear-velocity tomography models, based both on body-and surface-wave observations. At the regional scale, within the region of interest, correlation is complicated by the different resolution limits associated to different databases (surface waves, compressional waves, shear waves), and, accordingly, to different models; while a certain agreement appears to exist for what concerns the grand tectonic features in the area, heterogeneities of smaller scale are less robustly determined. Our new model is only one step towards the identification of a consensus model of European/Mediterranean uppermantle structure: on the basis of the findings discussed here, we expect that important improvements will soon result from the combination, in new tomographic inversions, of fundamental-mode phase-anomaly data like ours with observations of surface-wave overtones, of body-wave travel times, of ambient ''noise'', and by accounting for an a-priori model of crustal structure more highly resolved than the one employed here.

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Section: The Ray-theory Limitmentioning

confidence: 99%

The European Upper Mantle as Seen by Surface Waves

Boschi¹,

Fry²,

Ekström³

et al. 2009

Arrays and Array Methods in Global Seismology

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“…Following Spetzler et al 2001Spetzler et al , 2002, if epicentral distance a minor-arc path, then K n;q = K 1;q ; ; ; : where H; = sin sin, and R 0 is the Earth's radius. For simplicity of presentation, we omit the source and receiver indices and use a coordinate system centered on the greatcircle linking the source and receiver ; and the assumption that the great-circle lies along the equator.…”

Section: Sensitivity Kernels For Minor and Major Arc Pathsmentioning

confidence: 99%

“…Ray-theory is a high frequency approximation, however, which is not justi ed in the presence of heterogeneities whose length-scale is comparable to the wavelength of the wave e.g., Woodhouse, 1974;Wang & Dahlen, 1995. For the ray approximation to be valid, the rst Fresnel zone must be smaller than the scale-length of the heterogeneity, which places limitations on the lateral resolution of seismic models based on ray-theory. The Born or Rytov approximation for surface wave scattering e.g., Woodhouse & Girnius, 1982;Yomogida & Aki, 1987;Snieder & Romanowicz, 1988;Bostock & Kennett, 1992;Friederich et al, 1993, Friederich 1999Meier et al, 1997;Spetzler et al, 2001Spetzler et al, , 2002Yoshizawa & Kennett, 2002;Snieder, 2002 models the nite width of the surface wave sensitivity zone. Ritzwoller et al 2002 discussed the use of this approximation in the context of global surface wave tomography, calling the resulting method global di raction tomography.…”

Section: Introductionmentioning

confidence: 99%

Minor-arc and major-arc global surface wave diffraction tomography

Levshin¹,

Barmin²,

Ritzwoller³

et al. 2005

Physics of the Earth and Planetary Interiors

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We discuss extending global surface wave di raction tomography to accommodate major-arc dispersion measurements. The introduction of major-arc surface wave dispersion measurements improves path density and resolution in regions poorly covered by minor-arc measurements alone, as occurs in much of the southern hemisphere. The addition of major-arc measurements to the inversion for dispersion maps does not appreciably degrade the t to the minor-arc measurements but signi cantly improves the t to the major-arc measurements. For these reasons, we conclude that the addition of major-arc measurements is worthwhile in the interim until the broad-band network of ocean bottom or Antarctic stations is improved in the future.

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“…Williamson, 1991;Williamson & Worthington, 1993;Spetzler et al, 2001). Williamson, 1991;Williamson & Worthington, 1993;Spetzler et al, 2001).…”

Section: A Brief Historical Overviewunclassified

Full Seismic Waveform Modelling and Inversion

Fichtner¹

2011

Advances in Geophysical and Environmental Mechanics and Mathematics

371

349

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The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: deblik, BerlinPrinted on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) To my family and Carolin ForewordOur planet is permanently vibrating, excited by oceans, atmosphere, earthquakes, or man-made sources. Luckily, Earth's physical properties are such that these vibrations -elastic waves to be more specific -often propagate to large distances carrying information on the medium they encounter along the way. The problem of making an educated guess at the subsurface structure from observations of ground motions is as old as instrumental seismology itself (so not that old, maybe a century or so). Let us call the problem seismic tomography akin to CT scanning in medicine, a field seismologists have always envied. Because of limitations in illuminating the Earth with sufficient coverage we have never obtained the sharp and detailed internal structures so familiar from medical imaging.Up to now we have mostly cut corners in the way we model and fit our seismic data. We typically reduce long, wiggly seismograms to a few bytes of information (e.g. travel times, phase velocities) and try to explain these data with approximate theories. This has been for a good reason. Our computers were simply not fast and big enough to allow the calculation of complete wave fields through 3D Earth structures. Frequently the data just do not warrant the use of sophisticated physics.The situation regarding computational power in connection with 3D wave propagation has dramatically changed in the past few years. Even on a global scale the calculation of wave fields across the complete observed frequency range is in sight. On smaller scales (continents, basins, volcanoes, reservoirs) we are already witnessing the emergence of 3D wave propagation as the tool for data modelling, inversion and parameter studies.This was Albert Tarantola's (and others) dream 25 years ago: just simulate the physics correctly and let the data (i.e. the misfit to a theoretical seismogram) decide whether the Earth model is good or not. In his world (the probabilistic approach) this should be done using a Monte Carlo-type approach: calculate zillions of models and use all the results to estimate parameters and uncertainties. Unfortunately, we are not there yet. We still need to resort to linearisations around (hopefully good) starting models and employ adjoint-type techniques to update our Earth models. Fortunately, in many situations, good starting models can be found, making iterative waveform inversion the preferred tool to improve our Earth models using most or all of the observed data. vii viii ForewordThe book in your hands is the first to provide a broad overview on how to solve the forward problem to calculate accurate seismograms in 3D Earth m...

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Are we exceeding the limits of the Great Circle Approximation in global surface wave tomography?

Cited by 33 publications

References 24 publications

The European Upper Mantle as Seen by Surface Waves

The European Upper Mantle as Seen by Surface Waves

Minor-arc and major-arc global surface wave diffraction tomography

Full Seismic Waveform Modelling and Inversion

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