Three‐dimensional seismic refraction tomography: A comparison of two methods applied to data from the Faeroe Basin

Zelt, C. A.; Barton, P. J.

doi:10.1029/97jb03536

Cited by 511 publications

(592 citation statements)

References 20 publications

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“…The nonlinear iterative approach used here is essentially the same as that used in 3-D by Zelt and Barton [1998] and in 2-D by Zelt et al [2003]. Therefore, only a brief overview of the method is provided here.…”

Section: Wide-angle Seismic Datamentioning

confidence: 99%

“…A velocity model is sought that is the smoothest overall, while also providing an appropriate fit to the data. The method determines updates to an initial model over a series of iterations with new raypaths calculated at each iteration until the observed traveltimes are predicted by the model with a normalized misfit (c 2 ) of unity [Zelt, 1999;Zelt and Barton, 1998]. To achieve this, an objective function is minimized at each iteration which measures a weighted combination of the L 2 norm of the data misft and the second spatial derivative of the model.…”

Section: Wide-angle Seismic Datamentioning

confidence: 99%

“…[20] The regularized first-arrival traveltime tomography algorithm of Zelt and Barton [1998] was used to derive a minimum structure 2-D velocity model using only the first arrival times. The nonlinear iterative approach used here is essentially the same as that used in 3-D by Zelt and Barton [1998] and in 2-D by Zelt et al [2003].…”

Section: Wide-angle Seismic Datamentioning

confidence: 99%

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Crustal structure of the South American–Caribbean plate boundary at 67°W from controlled source seismic data

Magnani¹,

Zelt²,

Levander³

et al. 2009

J. Geophys. Res.

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[1] We present the results of new seismic reflection and wide-angle data across the SE Caribbean plate boundary. The 550 km long N-S profile crosses the structures involved in the active 55 Ma long continent-arc oblique collision between the Caribbean (CAR) and the South American (SA) plate. From the north to the south these structures include the accretionary prism, the extinct volcanic arc (Leeward Antilles arc), the Tertiary Bonaire basin, the continental-size dextral strike-slip fault system (San Sebastián-El Pilar fault), the allochthonous exhumed terranes, and the authocthonous fold and thrust belt (Caribbean Mountain system) and foreland basin. The wide-angle data show that these elements are characterized by different velocity structures and that they are separated by sharp lateral velocity variations. The Leeward Antilles arc exhibits a velocity structure similar to that of the Lesser Antilles active volcanic arc, indicating that the extinct arc has not been modified by the collision with the SA plate. The data show a $20 km change in crustal thickness across the San Sebastián fault, suggesting that the dextral strike-slip fault is a crustal feature that likely continues in the mantle as a primary strand of the plate boundary between the South American and the Caribbean plates. South of the strike-slip fault and beneath the exhumed eclogitic terranes, the data image a north dipping, high-velocity (>6.5 km/s) anomaly in the upper crust (3-11 km), indicating that high-pressure/low-temperature rocks are the likely lithologies responsible for the high seismic velocities and suggesting that exhumation of these assemblages is enabled by the strike-slip fault.

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Section: Wide-angle Seismic Datamentioning

confidence: 99%

Section: Wide-angle Seismic Datamentioning

confidence: 99%

Section: Wide-angle Seismic Datamentioning

confidence: 99%

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Crustal structure of the South American–Caribbean plate boundary at 67°W from controlled source seismic data

Magnani¹,

Zelt²,

Levander³

et al. 2009

J. Geophys. Res.

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“…The maximum achievable resolution of the final FWI velocity model was assessed by a series of checkerboard tests (Zelt and Barton 1998). Alternating velocity perturbations of ± 2% were introduced into the starting velocity model in checkerboard patterns to create reference models with anomaly dimensions of 10.0 km x 2.0 km, 5.0 km x 1.0 km, and 2.5 km x 0.5 km (Fig.…”

Section: Checkerboardsmentioning

confidence: 99%

Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Davy

Morgan

Minshull

et al. 2017

Geophysical Journal International

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SummaryContinental hyperextension during magma-poor rifting at the Deep Galicia Margin is characterised by a complex pattern of faulting, thin continental fault blocks, and the serpentinisation, with local exhumation, of mantle peridotites along the S-reflector, interpreted as a detachment surface. In order to understand fully the evolution of these features, it is important to image seismically the structure and to model the velocity structure to the greatest resolution possible. Travel-time tomography models have revealed the longwavelength velocity structure of this hyperextended domain, but are often insufficient to match accurately the short-wavelength structure observed in reflection seismic imaging. Here we demonstrate the application of two-dimensional (2D) time-domain acoustic full-waveform inversion to deep water seismic data collected at the Deep Galicia Margin, in order to attain a

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“…Typically, formal inversion routines like damped least squares (DLSQ) or regularized inversions using conjugate gradient methods are invoked to solve the large number of linear equations (e.g. Thurber 1993;Zelt & Barton 1998). To allow for the use of these methods, the tomographic inversion problem is linearized, and the traveltime differences (residuals) between the observed data and synthetic traveltime data related to an initial (or previous) model are minimized in an iterative way (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Bayesian inversion of refraction seismic traveltime data

Ryberg

Haberland

2017

Geophysical Journal International

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S U M M A R YWe apply a Bayesian Markov chain Monte Carlo (McMC) formalism to the inversion of refraction seismic, traveltime data sets to derive 2-D velocity models below linear arrays (i.e. profiles) of sources and seismic receivers. Typical refraction data sets, especially when using the far-offset observations, are known as having experimental geometries which are very poor, highly ill-posed and far from being ideal. As a consequence, the structural resolution quickly degrades with depth. Conventional inversion techniques, based on regularization, potentially suffer from the choice of appropriate inversion parameters (i.e. number and distribution of cells, starting velocity models, damping and smoothing constraints, data noise level, etc.) and only local model space exploration. McMC techniques are used for exhaustive sampling of the model space without the need of prior knowledge (or assumptions) of inversion parameters, resulting in a large number of models fitting the observations. Statistical analysis of these models allows to derive an average (reference) solution and its standard deviation, thus providing uncertainty estimates of the inversion result. The highly non-linear character of the inversion problem, mainly caused by the experiment geometry, does not allow to derive a reference solution and error map by a simply averaging procedure. We present a modified averaging technique, which excludes parts of the prior distribution in the posterior values due to poor ray coverage, thus providing reliable estimates of inversion model properties even in those parts of the models. The model is discretized by a set of Voronoi polygons (with constant slowness cells) or a triangulated mesh (with interpolation within the triangles). Forward traveltime calculations are performed by a fast, finite-difference-based eikonal solver. The method is applied to a data set from a refraction seismic survey from Northern Namibia and compared to conventional tomography. An inversion test for a synthetic data set from a known model is also presented.

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Three‐dimensional seismic refraction tomography: A comparison of two methods applied to data from the Faeroe Basin

Cited by 511 publications

References 20 publications

Crustal structure of the South American–Caribbean plate boundary at 67°W from controlled source seismic data

Crustal structure of the South American–Caribbean plate boundary at 67°W from controlled source seismic data

Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Bayesian inversion of refraction seismic traveltime data

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