Journal articles: 'Seismic tomography'

1

By, T. L. "Crosshole seismics and seismic tomography." Geoexploration 24, no. 3 (October 1987): 275–76. http://dx.doi.org/10.1016/0016-7142(87)90072-x.

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Poupinet, Georges. "Seismic tomography." Endeavour 14, no. 2 (January 1990): 52–60. http://dx.doi.org/10.1016/0160-9327(90)90072-y.

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Williamson, Paul R. "Seismic Reflection Tomography." Exploration Geophysics 19, no. 1-2 (March 1988): 391–93. http://dx.doi.org/10.1071/eg988391.

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Ursin, Bjørn, Maarten V. de Hoop, Stig-Kyrre Foss, and Sverre Brandsberg-Dahl. "Seismic angle tomography." Leading Edge 24, no. 6 (June 2005): 628–34. http://dx.doi.org/10.1190/1.1946220.

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Chiao, Ling-Yun, and Ban-Yuan Kuo. "Multiscale seismic tomography." Geophysical Journal International 145, no. 2 (May 2001): 517–27. http://dx.doi.org/10.1046/j.0956-540x.2001.01403.x.

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Bregman, N. D., R. C. Bailey, and C. H. Chapman. "Crosshole seismic tomography." GEOPHYSICS 54, no. 2 (February 1989): 200–215. http://dx.doi.org/10.1190/1.1442644.

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Many tomographic interpretations of crosshole seismic traveltimes have approximated the raypaths with straight lines connecting the source and receiver. This approximation is valid where the velocity does not vary greatly, but in many regions of interest velocity variations of 10–20 percent or more are observed, causing significant ray curvature. Other work has taken this nonlinear effect into account, but there do not appear to be many cases of demonstrated success in its application to the crosshole seismic problem. We present here an iterative inversion scheme based on two‐dimensional ray tracing and its successful application to field data. The interpretation method iteratively ray traces and then updates the velocity model. Within each iteration, the differences between the data and the current model traveltimes obtained by ray tracing are related to the unknown velocity perturbations through a system of linear equations. A damped least‐squares method solves for the velocity perturbations which update the model. The iterations continue until the synthetic traveltimes fit the data to within the data error or until no improvement in the fit of the traveltimes is observed. The method is demonstrated on a small synthetic data set, where convergence to the correct solution is achieved in a few iterations. The method is then applied to field data from a crosshole experiment in crystalline rock. The frequency range of the seismograms is 1 to 6.6 kHz, allowing resolution of velocity structure on a scale of several meters. The resulting velocity image shows good agreement with other geologic and geophysical data. Synthetic Maslov seismograms calculated for the derived velocity model agree well with the waveform data, providing an independent test of the validity of the inversion method.

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Root, B. C. "Comparing global tomography-derived and gravity-based upper mantle density models." Geophysical Journal International 221, no. 3 (February 24, 2020): 1542–54. http://dx.doi.org/10.1093/gji/ggaa091.

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SUMMARY Current seismic tomography models show a complex environment underneath the crust, corroborated by high-precision satellite gravity observations. Both data sets are used to independently explore the density structure of the upper mantle. However, combining these two data sets proves to be challenging. The gravity-data has an inherent insensitivity in the radial direction and seismic tomography has a heterogeneous data acquisition, resulting in smoothed tomography models with de-correlation between different models for the mid-to-small wavelength features. Therefore, this study aims to assess and quantify the effect of regularization on a seismic tomography model by exploiting the high lateral sensitivity of gravity data. Seismic tomography models, SL2013sv, SAVANI, SMEAN2 and S40RTS are compared to a gravity-based density model of the upper mantle. In order to obtain similar density solutions compared to the seismic-derived models, the gravity-based model needs to be smoothed with a Gaussian filter. Different smoothening characteristics are observed for the variety of seismic tomography models, relating to the regularization approach in the inversions. Various S40RTS models with similar seismic data but different regularization settings show that the smoothening effect is stronger with increasing regularization. The type of regularization has a dominant effect on the final tomography solution. To reduce the effect of regularization on the tomography models, an enhancement procedure is proposed. This enhancement should be performed within the spectral domain of the actual resolution of the seismic tomography model. The enhanced seismic tomography models show improved spatial correlation with each other and with the gravity-based model. The variation of the density anomalies have similar peak-to-peak magnitudes and clear correlation to geological structures. The resolvement of the spectral misalignment between tomographic models and gravity-based solutions is the first step in the improvement of multidata inversion studies of the upper mantle and benefit from the advantages in both data sets.

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Tsai, Victor C., Christian Huber, and Colleen A. Dalton. "Towards the geological parametrization of seismic tomography." Geophysical Journal International 234, no. 2 (March 24, 2023): 1447–62. http://dx.doi.org/10.1093/gji/ggad140.

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SUMMARY Seismic tomography is a cornerstone of geophysics and has led to a number of important discoveries about the interior of the Earth. However, seismic tomography remains plagued by the large number of unknown parameters in most tomographic applications. This leads to the inverse problem being underdetermined and requiring significant non-geologically motivated smoothing in order to achieve unique answers. Although this solution is acceptable when using tomography as an explorative tool in discovery mode, it presents a significant problem to use of tomography in distinguishing between acceptable geological models or in estimating geologically relevant parameters since typically none of the geological models considered are fit by the tomographic results, even when uncertainties are accounted for. To address this challenge, when seismic tomography is to be used for geological model selection or parameter estimation purposes, we advocate that the tomography can be explicitly parametrized in terms of the geological models being tested instead of using more mathematically convenient formulations like voxels, splines or spherical harmonics. Our proposition has a number of technical difficulties associated with it, with some of the most important ones being the move from a linear to a non-linear inverse problem, the need to choose a geological parametrization that fits each specific problem and is commensurate with the expected data quality and structure, and the need to use a supporting framework to identify which model is preferred by the tomographic data. In this contribution, we introduce geological parametrization of tomography with a few simple synthetic examples applied to imaging sedimentary basins and subduction zones, and one real-world example of inferring basin and crustal properties across the continental United States. We explain the challenges in moving towards more realistic examples, and discuss the main technical difficulties and how they may be overcome. Although it may take a number of years for the scientific program suggested here to reach maturity, it is necessary to take steps in this direction if seismic tomography is to develop from a tool for discovering plausible structures to one in which distinct scientific inferences can be made regarding the presence or absence of structures and their physical characteristics.

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Rammah, Khader, Mostafa Ismail, Jesse Costa, and Mario Riccio Filho. "A new seismic tomography system for geotechnical centrifuges." Soils and Rocks 46, no. 1 (December 1, 2022): e2023000922. http://dx.doi.org/10.28927/sr.2023.000922.

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Seismic tomography has been extensively used in geophysics for different purposes, including geological mapping, characterisation of inner earth structure and prospecting for oil and gas. In geophysics, seismic or electromagnetic waves are commonly used to provide tomographic information. In the geotechnical area, seismic tomography is emerging as a promising technique that can be used to determine the spatial variability of shear wave velocities and hence the small strain stiffness of geomaterials, especially when used in the centrifuge where in-situ stress conditions can be mimicked closely. This paper describes the development of a seismic tomography technique in the centrifuge. This technology can be used to image variations of soil stiffness under various mechanical, chemical and physical conditions. The paper describes the various components of the system, which includes arrays of small-size bender elements, hardware and software used to transmit, receive and acquire the shear wave signals during a centrifuge test. The paper illustrates the performance of the system at both 1g and in the centrifuge. Results of tomographic inversion performed on travel-time data obtained from these tests are discussed.

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Lazarević, Luka, Dejan Vučković, Milica Vilotijević, and Zdenka Popović. "Application of seismic tomography for assessment of the railway substructure condition." Structural Health Monitoring 18, no. 3 (May 29, 2018): 792–805. http://dx.doi.org/10.1177/1475921718774778.

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This article presents results obtained in the research conducted on railway infrastructure in Serbia, which aimed at prediction of substructure condition based on the analysis of track quality. It presents the results of seismic tomography application as non-destructive procedure for assessment of railway substructure condition. Track geometry quality was assessed according to analysis of longitudinal level data, which was recorded during regular track geometry inspections. Track section for application of seismic tomography was chosen on the basis of analysed track geometry data recorded during the regular track geometry inspections in 2006, 2008, 2009, 2012, 2013 and 2014. Tomographic imaging of railway platform on Test Section enabled the creation of two-dimensional finite element model, which was used for determination of propagation speed of seismic P-waves. Seismic tomography on Test Section, which is the part of the international railway line Belgrade–Vrbnica, was performed in 2014. Obtained tomographic image was discussed and compared to track geometry data recorded during the regular track geometry inspections.

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11

Witten, Alan J. "Seismic Reflection Diffraction Tomography." Journal of Environmental and Engineering Geophysics 1, no. 3 (December 1996): 205–13. http://dx.doi.org/10.4133/jeeg1.3.205.

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12

Myron, James R., Larry R. Lines, and R. Philip Bording. "Computers in Seismic Tomography." Computers in Physics 3, no. 2 (1989): 26. http://dx.doi.org/10.1063/1.4822829.

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Julian, B. R., and G. R. Foulger. "Time-dependent seismic tomography." Geophysical Journal International 182, no. 3 (July 8, 2010): 1327–38. http://dx.doi.org/10.1111/j.1365-246x.2010.04668.x.

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14

Doornbos, Durk J. "Diffraction and seismic tomography." Geophysical Journal International 108, no. 1 (January 1992): 256–66. http://dx.doi.org/10.1111/j.1365-246x.1992.tb00854.x.

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15

Shen, Yang. "Finite‐frequency seismic tomography." Journal of the Acoustical Society of America 119, no. 5 (May 2006): 3307–8. http://dx.doi.org/10.1121/1.4786291.

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Murphy, Gary E., and Samuel H. Gray. "Manual seismic reflection tomography." GEOPHYSICS 64, no. 5 (September 1999): 1546–52. http://dx.doi.org/10.1190/1.1444658.

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Prestack depth migration needs a good velocity model to produce a good image; in fact, finding the velocity model is one of the goals of prestack depth migration. Migration velocity analysis uses information produced by the migration to update the current velocity model for use in the next migration iteration. Several techniques are currently used to estimate migration velocities, ranging from trial and error to automatic methods like reflection tomography. Here, we present a method that combines aspects of some of the more accurate methods into an interactive procedure for viewing the effects of residual normal moveout corrections on migrated common reflection point (CRP) gathers. The residual corrections are performed by computing traveltimes along raypaths through both the current velocity model and the velocity model plus suggested model perturbations. The differences between those sets of traveltimes are related to differences in depth, allowing the user to preview the approximate effects of a velocity change on the CRP gathers without remigrating the data. As with automatic tomography, the computed depth differences are essentially backprojected along raypaths through the model, yielding a velocity update that flattens the gathers. Unlike automatic tomography, in which an algebraic inverse problem is solved by the computer for all geologic layers simultaneously, our method estimates shallow velocities before proceeding deeper and requires substantial user intervention, both in flattening individual CRP gathers and in deciding the appropriateness of the suggested velocity updates in individual geologic units.

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Bernauer, Moritz, Andreas Fichtner, and Heiner Igel. "Inferring earth structure from combined measurements of rotational and translational ground motions." GEOPHYSICS 74, no. 6 (November 2009): WCD41—WCD47. http://dx.doi.org/10.1190/1.3211110.

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We introduce a novel variant of seismic tomography that is based on colocated measurements of rotational and translational ground motions. Our aim is to assess whether rotations may be incorporated successfully into seismic inverse problems to produce better resolved and more realistic tomographic images. Our methodology is based on the definition of apparent S-wave speed as the ratio of rms velocity and rotation amplitudes. The principal advantages of this definition are that (1) no traveltimes measurements are needed and (2) the apparent S-wave speed is independent of source magnitude and source timing. We derive finite-frequency kernels for apparent S-wave speed by using a combination of the adjoint method and ray approximation. The properties of these kernels as a function of frequency bandwidth can be illustrated along with their usefulness for seismic tomography. In multifrequency synthetic inversions, we consider local crosshole tomography and regional-scale earthquake tomography. Our results indicate that S-wave speed variations can be retrieved accurately from colocated rotation and translation measurements, suggesting that our methodology is a promising extension of conventional seismic tomography. Further, apparent S-wave speed can be used to increase vertical resolution in teleseismic tomography for local structures.

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LeBlanc, Anne-Marie, Richard Fortier, Michel Allard, Calin Cosma, and Sylvie Buteau. "Seismic cone penetration test and seismic tomography in permafrost." Canadian Geotechnical Journal 41, no. 5 (September 1, 2004): 796–813. http://dx.doi.org/10.1139/t04-026.

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Two high-resolution multi-offset vertical seismic profile (VSP) surveys were carried out in a permafrost mound near Umiujaq in northern Quebec, Canada, while performing seismic cone penetration tests (SCPT) to study the cryostratigraphy and assess the body waves velocities and the dynamic properties of warm permafrost. Penetrometer-mounted triaxial accelerometers were used as the VSP receivers, and a swept impact seismic technique (SIST) source generating both compressional and shear waves was moved near the surface following a cross configuration of 40 seismic shot-point locations surrounding each of the two SCPTs. The inversion of travel times based on a simultaneous iterative reconstruction technique (SIRT) provided tomographic images of the distribution of seismic velocities in permafrost. The Young's and shear moduli at low strains were then calculated from the seismic velocities and the permafrost density measured on core samples. The combination of multi-offset VSP survey, SCPT, SIST, and SIRT for tomographic imaging led to new insights in the dynamic properties of permafrost at temperatures close to 0 °C. The P- and S-wave velocities in permafrost vary from 2400 to 3200 m/s and from 900 to 1750 m/s, respectively, for a temperature range between 0.2 and 2.0 °C. The Young's modulus varies from 2.15 to 13.65 GPa, and the shear modulus varies from 1.00 to 4.75 GPa over the same range of temperature.Key words: permafrost, seismic cone penetration test, vertical seismic profiling, seismic tomography, dynamic properties.

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Peterson, J. E., and A. Davey. "Crossvalidation method for crosswell seismic tomography." GEOPHYSICS 56, no. 3 (March 1991): 385–89. http://dx.doi.org/10.1190/1.1443055.

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Crosswell seismic tomography is used to determine the variation of elastic wave velocity or attenuation between two boreholes and, if possible, boreholes and the surface from which they are drilled. In a transmission tomographic survey, traveltimes or amplitudes are measured for many raypaths between the boreholes and the surface. The data are inverted for velocity and attenuation, respectively. In this paper we only discuss traveltimes, but the methods are equally applicable to amplitude inversions.

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Sari, Ayu Wita, and Gede Bayu Suparta. "PENCITRAAN TOMOGRAFI SEISMIK 3-D UNTUK STRUKTUR INTERNAL DI BAWAH GUNUNGAPI MERAPI MENGGUNAKAN SOFTWARE LOTOS-10." Spektra: Jurnal Fisika dan Aplikasinya 3, no. 2 (August 30, 2018): 105–16. http://dx.doi.org/10.21009/spektra.032.05.

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Abstrak Telah dilakukan penelitian pencitraan tomografi seismik 3D untuk stuktur internal di bawah Gunung Merapi dengan empat stasiun pencatat gempa dan gempa vulkanik sebagai sumber sinar gelombang. Penelitian ini menggunakan perangkat LOTOS-10 (Local Tomography Software 10) untuk inversi tomografi seismik 3D. Karakteristik medium bawah Gunung Merapi dapat digambarkan oleh parameter fisis seperti kecepatan gelombang primer dan sekunder. Hasil pengolahan data seismograf menunjukkan metoda tomografi seismik dapat mengungkap struktur bawah permukaan Gunung Merapi melalui distribusi anomali deviasi kecepatan dan Vp/Vs ratio. Kualitas citra yang dihasilkan dengan menggunakan gelombang primer lebih jelas resolusinya dan waktu yang digunakan lebih efesien, sehingga dapat digunakan sebagai informasi mitigasi bencana sebelum gempa erupsi terjadi. Daerah anomali negatif yang diperoleh terletak di bawah puncak Gunung Merapi pada kedalaman 3 - 5 km mempunyai karakter fisis yaitu zona lemah, kurang kompak, panas dan heterogen. Daerah anomali tersebut dapat diinterpretasikan sebagai keberadaan zona materi panas yang berasosiasi dengan sisa dapur magma dangkal. Kata-kata kunci: Gunung api Merapi, sifat fisis, tomografi seismic, lotos-10. Abstract 3D seismic tomography imaging research conducted for internal structures under Merapi Volcano with four earthquake recording and volcanic earthquake stations as a source of wave rays. This study used LOTOS-10 (Local Tomography Software 10) for 3D seismic tomography inversion. Characteristics of the medium under Merapi Volcano described by physical parameters such as primary and secondary wave velocities. The result of seismograph data processing shows seismic tomography method can reveal the subsurface structure of the Merapi Volcano through the distribution of deviation anomaly speed and Vp / Vs ratio. Image quality generated by using primary wave more clearly the resolution and time used more efficient, so that can be used as disaster mitigation information before earthquake eruption happened. The negative anomaly area obtained under the peak of Merapi Volcano at a depth of 3 - 5 km has the physical characteristics of weak, less compact, hot and heterogeneous zones. The anomalous region can interpret as the existence of a zone of heat material associated with the rest of the shallow magma kitchen. Keywords: Mount of Merapi, physical character, Seismic of Tomography, lotos-10.

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Ritsema, Jeroen, and Vedran Lekić. "Heterogeneity of Seismic Wave Velocity in Earth's Mantle." Annual Review of Earth and Planetary Sciences 48, no. 1 (May 30, 2020): 377–401. http://dx.doi.org/10.1146/annurev-earth-082119-065909.

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Seismology provides important constraints on the structure and dynamics of the deep mantle. Computational and methodological advances in the past two decades improved tomographic imaging of the mantle and revealed the fine-scale structure of plumes ascending from the core-mantle boundary region and slabs of oceanic lithosphere sinking into the lower mantle. We discuss the modeling aspects of global tomography including theoretical approximations, data selection, and model fidelity and resolution. Using spectral, principal component, and cluster analyses, we highlight the robust patterns of seismic heterogeneity, which inform us of flow in the mantle, the history of plate motions, and potential compositionally distinct reservoirs. In closing, we emphasize that data mining of vast collections of seismic waveforms and new data from distributed acoustic sensing, autonomous hydrophones, ocean-bottom seismometers, and correlation-based techniques will boost the development of the next generation of global models of density, seismic velocity, and attenuation. ▪ Seismic tomography reveals the 100-km to 1,000-km scale variation of seismic velocity heterogeneity in the mantle. ▪ Tomographic images are the most important geophysical constraints on mantle circulation and evolution.

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Serdyukov, Alexandr S., and Anton A. Duchkov. "Hybrid Kinematic-Dynamic Approach to Seismic Wave-Equation Modeling, Imaging, and Tomography." Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/543540.

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Estimation of the structure response to seismic motion is an important part of structural analysis related to mitigation of seismic risk caused by earthquakes. Many methods of computing structure response require knowledge of mechanical properties of the ground which could be derived from near-surface seismic studies. In this paper we address computationally efficient implementation of the wave-equation tomography. This method allows inverting first-arrival seismic waveforms for updating seismic velocity model which can be further used for estimating mechanical properties. We present computationally efficient hybrid kinematic-dynamic method for finite-difference (FD) modeling of the first-arrival seismic waveforms. At every time step the FD computations are performed only in a moving narrowband following the first-arrival wavefront. In terms of computations we get two advantages from this approach: computation speedup and memory savings when storing computed first-arrival waveforms (it is not necessary to make calculations or store the complete numerical grid). Proposed approach appears to be specifically useful for constructing the so-called sensitivity kernels widely used for tomographic velocity update from seismic data. We then apply the proposed approach for efficient implementation of the wave-equation tomography of the first-arrival seismic waveforms.

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Rao, Ying, and Yanghua Wang. "Fracture effects in seismic attenuation images reconstructed by waveform tomography." GEOPHYSICS 74, no. 4 (July 2009): R25—R34. http://dx.doi.org/10.1190/1.3129264.

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We have investigated seismic waveform tomography to characterize fractures in petroleum reservoirs. Seismic reflection data are used in a frequency-domain inversion to reconstruct subsurface attenuation images. The images show fracture distributions, from which fracture density is estimated. Fractures smaller than or equal to a half-wavelength of seismic act as single scatterers, producing images of strong attenuation ellipses and from which fracture density can be estimated. When fracture size approaches one wavelength, fracture orientation affects the attenuation image. Horizontal fractures act as individual reflectors and produce strong tomographic attenuation images from which fracture density can be estimated. The strength of the attenuation image decreases when the fracture angle relative to horizontal increases; vertical fractures produce the weakest attenuation image. Consequently, the accuracy of fracture density measurements decreases with increased fracture angle unless waveform tomography includes different seismic modes acquired from several directions.

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24

Carrion, Philip. "Dual tomography for imaging complex structures." GEOPHYSICS 56, no. 9 (September 1991): 1395–404. http://dx.doi.org/10.1190/1.1443159.

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The geophysical community admits that geotomography is a workable way to obtain accurate estimates of seismic velocity in complex structures. So‐called dual tomography improves the resolution of computed tomograms and thus can be applied to different geophysical and nongeophysical problems. Dual tomography emerges as a generalized approach to linearized constrained inversion. Dual inversion transforms a generalized constrained optimization problem being formulated in the physical space of seismic velocities to a dual unconstrained problem posed in the vector space of Lagrangian multipliers. It is a parametric optimization problem, with unknown solutions that are always perpendicular to the null‐space of a tomographic matrix. Imposed constraints improve the resolution and act as if the angular aperture coverage was extended. Thus dual tomography is able to quash image blurring associated with incomplete angular recording. Dual tomography does not require accurate knowledge of initial model. One starts with an arbitrary homogeneous medium and updates the medium in the course of iterations. Dual tomography does not require direct inversion of matrices and therefore it is relatively fast. Preliminary results indicate that dual tomography typically yields better images compared with algebraic reconstruction technique (ART), simultaneous reconstruction technique (SIRT), and other conventional techniques especially for limited angular aperture experiments typically used in seismic exploration.

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Tanimoto, T., and T. Lay. "Mantle dynamics and seismic tomography." Proceedings of the National Academy of Sciences 97, no. 23 (October 17, 2000): 12409–10. http://dx.doi.org/10.1073/pnas.210382197.

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Hildebrand, J. A., L. M. Dorman, P. T. C. Hammer, A. E. Schreiner, and B. D. Cornuelle. "Seismic tomography of Jasper Seamount." Geophysical Research Letters 16, no. 12 (December 1989): 1355–58. http://dx.doi.org/10.1029/gl016i012p01355.

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Trubitsyn, V. P. "Seismic tomography and continental drift." Izvestiya, Physics of the Solid Earth 44, no. 11 (November 2008): 857–72. http://dx.doi.org/10.1134/s1069351308110013.

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White, D. J. "Two-Dimensional Seismic Refraction Tomography." Geophysical Journal International 97, no. 2 (May 1989): 223–45. http://dx.doi.org/10.1111/j.1365-246x.1989.tb00498.x.

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Haned, A., E. Stutzmann, M. Schimmel, S. Kiselev, A. Davaille, and A. Yelles-Chaouche. "Global tomography using seismic hum." Geophysical Journal International 204, no. 2 (December 30, 2015): 1222–36. http://dx.doi.org/10.1093/gji/ggv516.

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Yuan, Yanhua O., Frederik J. Simons, and Jeroen Tromp. "Double-difference adjoint seismic tomography." Geophysical Journal International 206, no. 3 (June 24, 2016): 1599–618. http://dx.doi.org/10.1093/gji/ggw233.

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Steck, L. K., W. S. Phillips, K. Mackey, M. L. Begnaud, R. J. Stead, and C. A. Rowe. "Seismic tomography of crustalPandSacross Eurasia." Geophysical Journal International 177, no. 1 (April 2009): 81–92. http://dx.doi.org/10.1111/j.1365-246x.2009.04109.x.

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Lees, Jonathan M. "Seismic tomography of magmatic systems." Journal of Volcanology and Geothermal Research 167, no. 1-4 (November 2007): 37–56. http://dx.doi.org/10.1016/j.jvolgeores.2007.06.008.

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Tozer, D. C. "Seismic tomography and mantle circulation." Physics of the Earth and Planetary Interiors 70, no. 1-2 (February 1992): 138–40. http://dx.doi.org/10.1016/0031-9201(92)90174-t.

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Zhao, DaPeng, JianShe Lei, and Lucy Liu. "Seismic tomography of the Moon." Science Bulletin 53, no. 24 (November 3, 2008): 3897–907. http://dx.doi.org/10.1007/s11434-008-0484-1.

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OOI, Toyoki, and Fumio NAKADA. "Computational Method of Seismic Tomography." Geological data processing 1989, no. 14B (1989): 41–50. http://dx.doi.org/10.6010/geoinformatics1975.1989.14b_41.

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Meyerholtz, Keith A., Gary L. Pavlis, and Sally A. Szpakowski. "Convolutional quelling in seismic tomography." GEOPHYSICS 54, no. 5 (May 1989): 570–80. http://dx.doi.org/10.1190/1.1442684.

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This paper introduces convolutional quelling as a technique to improve imaging of seismic tomography data. We show the result amounts to a special type of damped, weighted, least‐squares solution. This insight allows us to implement the technique in a practical manner using a sparse matrix, conjugate gradient equation solver. We applied the algorithm to synthetic data using an eight nearest‐neighbor smoothing filter for the quelling. The results were found to be superior to a simple, least‐squares solution because convolutional quelling suppresses side bands in the resolving function that lead to imaging artifacts.

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Cardaci, C., M. Coviello, G. Lombardo, G. Patané, and R. Scarpa. "Seismic tomography of Etna volcano." Journal of Volcanology and Geothermal Research 56, no. 4 (August 1993): 357–68. http://dx.doi.org/10.1016/0377-0273(93)90002-9.

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NOLET, G., S. KARATO, and R. MONTELLI. "Plume fluxes from seismic tomography." Earth and Planetary Science Letters 248, no. 3-4 (August 30, 2006): 685–99. http://dx.doi.org/10.1016/j.epsl.2006.06.011.

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Phạm, Thế Hoàng Hà, Huy Hien Đoàn, Quang Minh Tạ, Thị Lụa Mai, and Hoàng Anh Nguyễn. "Some results of seismic travel-time reflection tomography study." Petrovietnam Journal 10 (November 30, 2021): 4–16. http://dx.doi.org/10.47800/pvj.2021.10-01.

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Velocity model is essential for seismic data processing as it plays an important role in migration processes as well as time depth conversion. There are several techniques to reach that goal, among which tomographic inversion is an efficient one. As an upgrade version of handpicked velocity analysis, the tomography technique is based on the reflection ray tracing and conjugate gradient method to estimate an optimum velocity model and can create an initial high quality model for other intensive imaging and modelling module such as reverse-time migration (RTM) and full-waveform inversion (FWI). For the mentioned benefit, we develop a seismic travel-time reflection tomography (SeisT) module to study the accuracy of the approach along with building the technical capability in seismic processing. The accuracy of the module has been tested by both synthetic and real seismic field data; the efficiency and the accuracy of the model have been proven in terms of development method as well as field data application.

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SHIOBARA, Hajime. "Seismic Tomography for Refraction Profiling: Numerical Experiment." Zisin (Journal of the Seismological Society of Japan. 2nd ser.) 41, no. 4 (1988): 549–61. http://dx.doi.org/10.4294/zisin1948.41.4_549.

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Archambeau, Charles B. "Passive Seismic Tomography: 3-D imaging in tectonically active regions." Global Tectonics and Metallogeny 8, no. 1-4 (January 1, 2003): 205. http://dx.doi.org/10.1127/gtm/8/2003/205.

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MIKADA, Hitoshi. "Seismic Scattering Theory and Its Application to Seismic Tomography." Journal of Geography (Chigaku Zasshi) 104, no. 7 (1995): 922–33. http://dx.doi.org/10.5026/jgeography.104.7_922.

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Timotius, Hagayudha, and Yulinar Firdaus. "QUALITY IMPROVEMENT OF SEISMIC IMAGE FROM 2D PSDM (PRE STACK DEPTH MIGRATION) USING TOMOGRAPHY FOR INTERVAL VELOCITY MODEL REFINEMENT." BULLETIN OF THE MARINE GEOLOGY 28, no. 2 (February 15, 2016): 43. http://dx.doi.org/10.32693/bomg.28.2.2013.59.

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The main goal of seismic exploration is to get an accurate image of subsurface section so it can be easily interpreted. Pre Stack Depth Migration (PSDM) is such a powerful imaging tool especially for complex area such an area where strong lateral velocity variations exist. The main challenge of PSDM is the need of accurate interval velocity model.In this research, Dix Transformation, coherency inversion, and tomography are used for initial interval velocity model, and then tomography is used for interval velocity model refinement. We compare also between seismic image resulted from PSDM and PSTM to determine the best method. The seismic data that processed in this paper is derived from north western part of Australian Waters. Kata kunci: Pre Stack Depth Migration, Dix Transformation, coherency inversion, tomography. Tujuan utama dari eksplorasi seismik adalah menghasilkan citra yang akurat dari penampang bawah permukaan sehingga diinterpretasi lebih mudah. Pre Stack Depth Migration (PSDM) merupakan suatu metode yang memberikan hasil peningkatan kualitas citra seismik pada daerah kompleks dimana terjadi variasi kecepatan lateral yang signifikan. Salah satu syarat penting yang harus dipenuhi agar hasil PSDM lebih optimal adalah model kecepatan interval yang akurat. Dalam penelitian ini Transformasi Dix, inversi koheren, dan tomografi digunakan untuk memenuhi syarat tersebut. Perbandingan hasil penampang seimik PSDM dan PSTM dilakukan untuk menentukan metode terbaik. Data seismik yang diolah dalam tulisan ini berasal dari wilayah Perairan Baratlaut Australia. Kata kunci: Pre Stack Depth Migration, Transformasi Dix, inversi koheren, tomografi

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Tungka, Marie. "Determining subsurface geology with seismic refraction tomography survey." IOP Conference Series: Earth and Environmental Science 1003, no. 1 (April 1, 2022): 012037. http://dx.doi.org/10.1088/1755-1315/1003/1/012037.

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Abstract Seismic refraction tomography survey is one of the geophysical techniques that is the most popular and commonly used to determine subsurface geology in engineering application. It is fast, reliable, cheaper and cover bigger area in shorter time compared with borehole drilling and other geophysical techniques in providing continuous information on subsurface geology along the lengths of the seismic survey lines. However, the success of seismic refraction tomography survey depends on a few factors such as noise background, top soil features, geology of the site, limitation of the equipment, understanding of the theories and experiences in interpreting the seismic refraction tomography survey data. The method of seismic refraction tomography survey measures the first arrival time of the primary waves through the earth material after seismic signals were generated at several shot points with sledge hammer or explosives. In this paper, the applications of seismic refraction tomography survey in investigating the subsurface geology were discussed in two case studies. The first case study discussed the effect of geophone interval in the limit of depth penetration of seismic refraction tomography survey. Increasing the geophone interval would increase the limit of depth penetration, which helped in mapping the very deep bedrock profile. The second case study showed that the seismic refraction tomography survey results were able to indicate the highly irregular bedrock profiles and complexity of the subsurface geology such as shear zones. It was able to show the extent of the shear zones at the project area, which would have been missed by merely doing borehole drilling. Hydrothermally altered granite and quartz veins were encountered in the boreholes located along the shear zones. Both case studies showed good correlations between boreholes and seismic refraction tomography survey results.

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El-kaseeh, George, and Kevin L. McCormack. "Multi-Scale Seismic Measurements for Site Characterization and CO2 Monitoring in an Enhanced Oil Recovery/Carbon Capture, Utilization, and Sequestration Project, Farnsworth Field, Texas." Energies 16, no. 20 (October 19, 2023): 7159. http://dx.doi.org/10.3390/en16207159.

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To address the challenges of climate change, significantly more geologic carbon sequestration projects are beginning. The characterization of the subsurface and the migration of the plume of supercritical carbon dioxide are two elements of carbon sequestration that can be addressed through the use of the available seismic methods in the oil and gas industry. In an enhanced oil recovery site in Farnsworth, TX, we employed three separate seismic techniques. The three-dimensional (3D) surface seismic survey required significant planning, design, and processing, but produces both a better understanding of the subsurface structure and a three-dimensional velocity model, which is essential for the second technique, a timelapse vertical seismic profile, and the third technique, cross-well seismic tomography. The timelapse 3D Vertical Seismic Profile (3D VSP) revealed both significant changes in the reservoir between the second and third surveys and geo-bodies that may represent the extent of the underground carbon dioxide. The asymmetry of the primary geo-body may indicate the preferential migration of the carbon dioxide. The third technique, cross-well seismic tomography, suggested a strong correlation between the well logs and the tomographic velocities, but did not observe changes in the injection interval.

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Bishop, T. N., K. P. Bube, R. T. Cutler, R. T. Langan, P. L. Love, J. R. Resnick, R. T. Shuey, D. A. Spindler, and H. W. Wyld. "Tomographic determination of velocity and depth in laterally varying media." GEOPHYSICS 50, no. 6 (June 1985): 903–23. http://dx.doi.org/10.1190/1.1441970.

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Estimation of reflector depth and seismic velocity from seismic reflection data can be formulated as a general inverse problem. The method used to solve this problem is similar to tomographic techniques in medical diagnosis and we refer to it as seismic reflection tomography. Seismic tomography is formulated as an iterative Gauss‐Newton algorithm that produces a velocity‐depth model which minimizes the difference between traveltimes generated by tracing rays through the model and traveltimes measured from the data. The input to the process consists of traveltimes measured from selected events on unstacked seismic data and a first‐guess velocity‐depth model. Usually this first‐guess model has velocities which are laterally constant and is usually based on nearby well information and/or an analysis of the stacked section. The final model generated by the tomographic method yields traveltimes from ray tracing which differ from the measured values in recorded data by approximately 5 ms root‐mean‐square. The indeterminancy of the inversion and the associated nonuniqueness of the output model are both analyzed theoretically and tested numerically. It is found that certain aspects of the velocity field are poorly determined or undetermined. This technique is applied to an example using real data where the presence of permafrost causes a near‐surface lateral change in velocity. The permafrost is successfully imaged in the model output from tomography. In addition, depth estimates at the intersection of two lines differ by a significantly smaller amount than the corresponding estimates derived from conventional processing.

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Young, J. A. "Diffraction tomography applied to crosshole and VSP seismic data." Exploration Geophysics 20, no. 2 (1989): 169. http://dx.doi.org/10.1071/eg989169.

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Diffraction tomography is an approach to seismic inversion which is analogous to f-k migration. It differs from f-k migration in that it attempts to obtain a more quantitative rather than qualitative image of the Earth's subsurface. Diffraction tomography is based on the generalized projection-slice theorem which relates the scattered wave field to the Fourier spectrum of the scatterer. Factors such as the survey geometry and the source bandwidth determine the data coverage in the spatial Fourier domain which in turn determines the image resolution. Limited view-angles result in regions of the spatial Fourier domain with no data coverage, causing the solution to the tomographic reconstruction problem to be nonunique. The simplistic approach is to assume the missing samples are zero and perform a standard reconstruction but this can result in images with severe artefacts. Additional a priori information can be introduced to the problem in order to reduce the nonuniqueness and increase the stability of the reconstruction. This is the standard approach used in ray tomography but it is not commonly used in diffraction tomography applied to seismic data.This paper shows the application of diffraction tomography to crosshole and VSP seismic data. Using synthetic data, the effects on image resolution of the survey geometry and the finite source bandwidth are examined and techniques for improving image quality are discussed.

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Rao, Ying, Yanghua Wang, Shumin Chen, and Jianmin Wang. "Crosshole seismic tomography with cross-firing geometry." GEOPHYSICS 81, no. 4 (July 2016): R139—R146. http://dx.doi.org/10.1190/geo2015-0677.1.

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We have developed a case study of crosshole seismic tomography with a cross-firing geometry in which seismic sources were placed in two vertical boreholes alternatingly and receiver arrays were placed in another vertical borehole. There are two crosshole seismic data sets in a conventional sense. These two data sets are used jointly in seismic tomography. Because the local sediment is dominated by periodic, flat, thin layers, there is seismic anisotropy with different velocities in the vertical and horizontal directions. The vertical transverse isotropy anisotropic effect is taken into account in inversion processing, which consists of three stages in sequence. First, isotropic traveltime tomography is used for estimating the maximum horizontal velocity. Then, anisotropic traveltime tomography is used to invert for the anisotropic parameter, which is the normalized difference between the maximum horizontal velocity and the maximum vertical velocity. Finally, anisotropic waveform tomography is implemented to refine the maximum horizontal velocity. The cross-firing acquisition geometry significantly improves the ray coverage and results in a relatively even distribution of the ray density in the study area between two boreholes. Consequently, joint inversion of two crosshole seismic data sets improves the resolution and increases the reliability of the velocity model reconstructed by tomography.

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Wu, Ru‐Shan, and M. Nafi Toksöz. "Diffraction tomography and multisource holography applied to seismic imaging." GEOPHYSICS 52, no. 1 (January 1987): 11–25. http://dx.doi.org/10.1190/1.1442237.

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Seismic tomography is emerging as an imaging method for determining subsurface structure. When the view‐angle coverage is limited and the scale of the medium inhomogeneities is comparable with the wavelength, as is often true in geophysical applications, the performance of ordinary ray tomography becomes poor. Other tomographic methods are needed to improve the imaging process. Here we study diffraction tomography and multisource holography and evaluate their performances for surface reflection profiling (SRP), vertical seismic profiling (VSP), and cross‐hole measurements. Theoretical formulations are derived for two‐dimensional geometry in terms of line sources along a source line and line receivers along a receiver line. The theory for diffraction tomography is based on the Born or Rytov approximation. The performances of diffraction tomography and multisource holography are evaluated by examining the information coverage in the spatial frequency domain and by numerical examples. Multisource holography, which is similar to Kirchhoff‐type migration, often gives distorted images of the object. This distortion causes long tails of the image in the case of SRP and a strong noise belt in the case of VSP and is due to incomplete and nonuniform coverage of the object spectrum. The filtering operation of diffraction tomography helps in correcting the nonuniform coverage (including duplication) of the object spectrum in the reconstruction process and therefore reduces the distortions. On the other hand, multisource holography is better suited for imaging sharp boundaries with large acoustic impedance contrasts since diffraction tomography is restricted, as presently formulated, to weak inhomogeneities. In addition, multisource holography has the flexibility to be used with an arbitrary number of sources (including a single source). Its sampling interval is not restricted by the Nyquist frequency. Numerical examples show that combined data sets (such as surface reflection data combined with VSP data, or cross‐hole data combined with surface data, etc.) improve the image quality.

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Fernández-Ruiz, María R., Hugo F. Martins, Sonia Martin-Lopez, and Miguel Gonzalez-Herraez. "Submarine seismic tomography using optical fibres." Europhysics News 51, no. 3 (May 2020): 22–24. http://dx.doi.org/10.1051/epn/2020304.

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The repurpose of the available telecommunication fibre optical network as a seismic monitoring tool has been recently tested with very promising prospects. Optical fibre networks possess all the ingredients to become the next generation seismic monitoring system, offering high performance at minimum deployment and maintenance cost, especially at hardly accessible regions such as the oceans’ bottom.

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Journal articles on the topic 'Seismic tomography'

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