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1
Campman, X., K. van Wijk, C. D. Riyanti, J. Scales und G. Herman. „Imaging scattered seismic surface waves“. Near Surface Geophysics 2, Nr. 4 (01.08.2004): 223–30. http://dx.doi.org/10.3997/1873-0604.2004019.
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2
Ilchenko, V. V., M. M. Nikiforov, V. S. Mostovoy, B. O. Popkov, V. M. Loza O.L. und O. L. Kulskyi. „PECULIARITIES OF APPLICATION OF SEISMOACOUSTIC LOCATION FOR DETERMINATION OF MOVING OBJECTS“. Collection of scientific works of the Military Institute of Kyiv National Taras Shevchenko University, Nr. 74 (2022): 21–30. http://dx.doi.org/10.17721/2519-481x/2022/74-03.
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The work is related to the study of surface waves in solving seismic acoustic location problems during the movement of moving objects, and in assessing the accuracy of determining the coordinates of moving objects of different origins. In solving the inverse problems of seismic acoustic location, the surfaces of the wave that occur on the Earth's surface during the movement of a moving object are studied. The accuracy of the solution of the inverse problem directly depends on the errors: determination of the time of entry of the seismic acoustic wave, the velocity characteristics of the environment, noise of various origins, the choice of the geometry of the location of sensors. The need to study surface waves, namely Rayleigh Waves and Lion Waves, is justified because they propagate on the Earth's surface. The plane of oscillation of Rayleigh waves is vertical to the Earth's surface and direction of propagation, and Lev waves have a horizontal plane of oscillation. As one of the considered problems of seismic acoustic location as a source of energy of a moving object, we take seismic energy, which occurs during human walking. Human walking is periodic. It excites impulses of displacement in the geological environment. According to the known coefficient of rigidity of the medium, it is possible to determine what will be the maximum deviation of the seismic receiver. The paper investigates surface waves, Rayleigh and Lev in solving seismic acoustic location problems during human movement, and identifies factors that affect the accuracy of determining the coordinates of a moving object. In terms of using surface waves to solve seismic location problems to identify moving objects, they have the following advantages: the energy of these waves does not disappear deep into the Earth, but propagates below its surface; their formation takes more than 60% of the energy of the source, and the formation of deep waves only 8%, such waves have much more energy; From this it can be concluded that even at low energies of the excitation source surface waves can be used to solve seismic location problems during the movement of moving objects and to assess the accuracy of determining the coordinates of these objects.
3
Halliday, David F., Andrew Curtis, Johan O. A. Robertsson und Dirk-Jan van Manen. „Interferometric surface-wave isolation and removal“. GEOPHYSICS 72, Nr. 5 (September 2007): A69—A73. http://dx.doi.org/10.1190/1.2761967.
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The removal of surface waves (ground roll) from land seismic data is critical in seismic processing because these waves tend to mask informative body-wave arrivals. Removal becomes difficult when surface waves are scattered, and data quality is often impaired. We apply a method of seismic interferometry, using both sources and receivers at the surface, to estimate the surface-wave component of the Green’s function between any two points. These estimates are subtracted adaptively from seismic survey data, providing a new method of ground-roll removal that is not limited to nonscattering regions.
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Apostol, Bogdan Felix. „Seismological Problem, Seismic Waves and the Seismic Mainshock“. Mathematics 11, Nr. 17 (02.09.2023): 3777. http://dx.doi.org/10.3390/math11173777.
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The elastic wave equation with seismic tensorial force is solved in a homogeneous and isotropic medium (the Earth). Spherical-shell waves are obtained, which are associated to the primary P and S seismic waves. It is shown that these waves produce secondary waves with sources on the plane surface of a half-space, which have the form of abrupt walls with a long tail, propagating in the interior and on the surface of the half-space. These secondary waves are associated to the seismic mainshock. The results, previously reported, are re-derived using Fourier transformations and specific regularization procedures. The relevance of this seismic motion for the ground motion, the seismographs’ recordings and the effect of the inhomogeneities in the medium are discussed.
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Hartono, Hartono, Haerul Anwar, Rofiqul Umam und Hirotaka Takahashi. „An unsupervised machine learning algorithm approach using K-Means Clustering for optimizing Surface Wave Filtering in seismic reflection data“. Journal of Natural Sciences and Mathematics Research 10, Nr. 1 (31.07.2024): 114–27. http://dx.doi.org/10.21580/jnsmr.v10i1.22399.
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Surface waves often cause significant noise in seismic data, complicating the interpretation of subsurface structures. Traditional filtering methods, such as FK filtering, usually struggle with non-stationary noise and require extensive manual parameter tuning. This study explores the effectiveness of using K-means clustering, incorporating attributes such as amplitude, frequency, and phase to filter surface waves from seismic data. Synthetic seismic data were first generated to test the proposed method, ensuring its robustness before application to real field data. Attributes were extracted from each seismic trace, including instantaneous amplitude, frequency, and phase. These attributes were used as input parameters for the K-means clustering algorithm. The identified clusters corresponding to surface waves were then used to filter these waves from the seismic data. The K-Means clustering effectively differentiated surface waves from reflected waves in both synthetic and real seismic datasets. The method demonstrated that by including phase as an attribute, alongside amplitude and frequency, the accuracy of surface wave detection and filtering significantly improved. The synthetic data showed a clear separation of wave types, validating the method. When applied to real field data, the approach consistently removed surface waves, clarity of seismic reflections crucial for subsurface analysis.
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Apostol, Bogdan Felix. „Near-Field Seismic Motion: Waves, Deformations and Seismic Moment“. Axioms 11, Nr. 8 (17.08.2022): 409. http://dx.doi.org/10.3390/axioms11080409.
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The tensorial force acting in a localized seismic focus is introduced and the corresponding seismic waves are derived, as solutions of the elastic wave equation in a homogeneous and isotropic body. The deconvolution of the solution for a structured focal region is briefly discussed. The far-field waves are identified as P and S seismic waves. These are spherical-shell waves, with a scissor-like shape, and an amplitude decreasing with the inverse of the distance. The near-field seismic waves are spherical-shell waves, decreasing with the inverse of the squared distance. The amplitudes and the polarizations of the near-field seismic waves are given. The determination of the seismic-moment tensor and the earthquake parameters from measurements of the P and S seismic waves at Earth’s’ surface is briefly discussed. Similarly, the mainshock generated by secondary waves on Earth’s surface is reviewed. The near-field static deformations of a homogeneous and isotropic half-space are discussed and a method of determining the seismic-moment tensor from epicentral near-field (quasi-) static deformations in seismogenic regions is presented.
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Irie, Kiyoshi, Dorjpalam Saruul, Kazuo Dan und Haruhiko Torita. „Evaluation of the Strong Ground Motions in the Area Close to the Surface Faults“. Journal of Earthquake and Tsunami 12, Nr. 04 (Oktober 2018): 1841002. http://dx.doi.org/10.1142/s1793431118410026.
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In Japan, the seismic waves radiated from the fault in the surface layers above the seismogenic layer are not considered in the usual strong motion prediction. However, in the inland crustal earthquakes, the strong ground motions in the areas close to the surface faults could be influenced by the seismic waves radiated from the fault in the surface layers. Hence, we evaluated the seismic waves radiated from vertical strike-slip and dipping reverse faults in the surface layers to investigate their influence on the strong motions. The results of the strike-slip fault showed that the seismic waves of the fault normal (FN) component were larger than those of the fault parallel (FP) component in the period range of 0.5–5 s. At least, 80–90% of the FN component was attributed to the seismic wave radiated from the fault in the seismogenic layer. Almost 100% of the FP component was attributed to the seismic waves radiated from the fault in the surface layers. On the other hand, the results of the reverse fault showed that the seismic waves were not attributed to those from the fault in the surface layers.
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Jiang, Hui, Chunfeng Zhao, Yingjie Chen und Jian Liu. „Novel Frame-Type Seismic Surface Wave Barrier with Ultra-Low-Frequency Bandgaps for Rayleigh Waves“. Buildings 14, Nr. 8 (27.07.2024): 2328. http://dx.doi.org/10.3390/buildings14082328.
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Seismic surface waves carry significant energy that poses a major threat to structures and may trigger damage to buildings. To address this issue, the implementation of periodic barriers around structures has proven effective in attenuating seismic waves and minimizing structural dynamic response. This paper introduces a framework for seismic surface wave barriers designed to generate multiple ultra-low-frequency band gaps. The framework employs the finite-element method to compute the frequency band gap of the barrier, enabling a deeper understanding of the generation mechanism of the frequency band gap based on vibrational modes. Subsequently, the transmission rates of elastic waves through a ten-period barrier were evaluated through frequency–domain analysis. The attentional effects of the barriers were investigated by the time history analysis using site seismic waves. Moreover, the influence of the soil damping and material damping are separately discussed, further enhancing the assessment. The results demonstrate the present barrier can generate low-frequency band gaps and effectively attenuate seismic surface waves. These band gaps cover the primary frequencies of seismic surface waves, showing notable attenuation capabilities. In addition, the soil damping significantly contributes to the attenuation of seismic surface waves, resulting in an attenuation rate of 50%. There is promising potential for the application of this novel isolation technology in seismic engineering practice.
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Xu, Jixiang, Shitai Dong, Huajuan Cui, Yan Zhang, Ying Hu und Xiping Sun. „Near-surface scattered waves enhancement with source-receiver interferometry“. GEOPHYSICS 83, Nr. 6 (01.11.2018): Q49—Q69. http://dx.doi.org/10.1190/geo2017-0806.1.
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Near-surface scattered waves (NSWs) are the main noise in seismic data in areas with a complex near surface and can be divided into surface-to-surface scattered waves and body-to-surface scattered waves. We have developed a method for NSW enhancement that uses modified source-receiver interferometry. The method consists of two parts. First, deconvolutional intersource interferometry is used to cancel the common raypath of seismic waves from a near-surface scatterer to the common receiver and the receiver function. Second, convolutional interreceiver interferometry is used to compensate the common raypath of seismic waves from the common source to the near-surface scatterer and the source function. For an isotropic point scatterer near the earth’s surface in modified source-receiver interferometry, a body-to-surface scattered wave can be reconstructed by constructive interference not only among three body-to-surface scattered waves but also among a body-to-surface scattered wave and two surface-to-surface scattered waves; a surface-to-surface scattered wave can be reconstructed by constructive interference not only among three surface-to-surface scattered waves but also among a surface-to-surface scattered wave and two body-to-surface scattered waves. According to stationary phase analysis based on the superposition principle, we have developed a so-called dual-wheel driving configuration of modified source-receiver interferometry for enhancing NSWs in the data of conventional seismic exploration. The main advantages of the scheme are that (1) it can be used to enhance NSWs without the need for any a priori knowledge of topography and near-surface velocity, (2) it can be used to reconstruct NSWs from real sources to real receivers, including 3D near-surface side-scattered waves, and (3) it can be applied to conventional seismic data with finite-frequency bandwidth, spatially limited and sparse arrays, different source and receiver functions, and static correction. Numerically simulated data and field seismic data are used to demonstrate the feasibility and effectiveness of the scheme.
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Zeng, Yi, Liyun Cao, Sheng Wan, Tong Guo, Shuowei An, Yan-Feng Wang, Qiu-Jiao Du, Brice Vincent, Yue-Sheng Wang und Badreddine Assouar. „Inertially amplified seismic metamaterial with an ultra-low-frequency bandgap“. Applied Physics Letters 121, Nr. 8 (22.08.2022): 081701. http://dx.doi.org/10.1063/5.0102821.
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In last two decades, it has been theoretically and experimentally demonstrated that seismic metamaterials are capable of isolating seismic surface waves. Inertial amplification mechanisms with small mass have been proposed to design metamaterials to isolate elastic waves in rods, beams, and plates at low frequencies. In this Letter, we propose an alternative type of seismic metamaterial providing an ultra-low-frequency bandgap induced by inertial amplification. A unique kind of inertially amplified metamaterial is first conceived and designed. Its bandgap characteristics for flexural waves are then numerically and experimentally demonstrated. Finally, the embedded inertial amplification mechanism is introduced on a soil substrate to design a seismic metamaterial capable of strongly attenuating seismic surface waves around a frequency of 4 Hz. This work provides a promising alternative way to conceive seismic metamaterials to steer and control surface waves.
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Almuhaidib, Abdulaziz M., und M. Nafi Toksöz. „Numerical modeling of elastic-wave scattering by near-surface heterogeneities“. GEOPHYSICS 79, Nr. 4 (01.07.2014): T199—T217. http://dx.doi.org/10.1190/geo2013-0208.1.
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In land seismic data, scattering from surface and near-surface heterogeneities adds complexity to the recorded signal and masks weak primary reflections. To understand the effects of near-surface heterogeneities on seismic reflections, we simulated seismic-wave scattering from arbitrary-shaped, shallow, subsurface heterogeneities through the use of a perturbation method for elastic waves and finite-difference forward modeling. The near-surface scattered wavefield was modeled by looking at the difference between the calculated incident (i.e., in the absence of scatterers) and the total wavefields. Wave propagation was simulated for several earth models with different near-surface characteristics to isolate and quantify the influence of scattering on the quality of the seismic signal. The results indicated that the direct surface waves and the upgoing reflections were scattered by the near-surface heterogeneities. The scattering took place from body waves to surface waves and from surface waves to body waves. The scattered waves consisted mostly of body waves scattered to surface waves and were, generally, as large as, or larger than, the reflections. They often obscured weak primary reflections and could severely degrade the image quality. The results indicated that the scattered energy depended strongly on the properties of the shallow scatterers and increased with increasing impedance contrast, increasing size of the scatterers relative to the incident wavelength, decreasing depth of the scatterers, and increasing attenuation factor of the background medium. Also, sources deployed at depth generated weak surface waves, whereas deep receivers recorded weak surface and scattered body-to-surface waves. The analysis and quantified results helped in the understanding of the scattering mechanisms and, therefore, could lead to developing new acquisition and processing techniques to reduce the scattered surface wave and enhance the quality of the seismic image.
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Kuznetsov, Sergey V., und Aybek E. Nafasov. „Horizontal Acoustic Barriers for Protection from Seismic Waves“. Advances in Acoustics and Vibration 2011 (21.09.2011): 1–8. http://dx.doi.org/10.1155/2011/150310.
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The basic idea of a seismic barrier is to protect an area occupied by a building or a group of buildings from seismic waves. Depending on nature of seismic waves that are most probable in a specific region, different kinds of seismic barriers can be suggested. Herein, we consider a kind of a seismic barrier that represents a relatively thin surface layer that prevents surface seismic waves from propagating. The ideas for these barriers are based on one Chadwick's result concerning nonpropagation condition for Rayleigh waves in a clamped half-space, and Love's theorem that describes condition of nonexistence for Love waves. The numerical simulations reveal that to be effective the length of the horizontal barriers should be comparable to the typical wavelength.
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Edme, Pascal, und David F. Halliday. „Near-surface imaging using ambient-noise body waves“. Interpretation 4, Nr. 3 (01.08.2016): SJ55—SJ65. http://dx.doi.org/10.1190/int-2016-0002.1.
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We have introduced a workflow that allows subsurface imaging using upcoming body-wave arrivals extracted from ambient-noise land seismic data. Rather than using the conventional seismic interferometry approach based on correlation, we have developed a deconvolution technique to extract the earth response from the observed periodicity in the seismic traces. The technique consists of iteratively applying a gapped spiking deconvolution, providing multiple-free images with higher resolution than conventional correlation. We have validated the workflow for zero-offset traces with simple synthetic data and real data recorded during a small point-receiver land seismic survey.
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Neducza, Boriszláv. „Stacking of surface waves“. GEOPHYSICS 72, Nr. 2 (März 2007): V51—V58. http://dx.doi.org/10.1190/1.2431635.
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The seismic surface wave method (SWM) is a powerful means of characterizing near-surface structures. Although the SWM consists of only three steps (data acquisition, determination of dispersion curves, and inversion), it is important to take considerable care with the second step, determination of the dispersion curves. This step is usually completed by spectral analysis of surface waves (SASW) or multichannel analysis of surface waves (MASW). However, neither method is ideal, as each has its advantages and disadvantages. SASW provides higher horizontal resolution, but it is very sensitive to coherent noise and individual geophone coupling. MASW is a robust method able to separate different wave types, but its horizontal resolution is lower. Stacking of surface waves (SSW) is a good compromise between SASW and MASW. Using a reduced number of traces increases the horizontal resolution of MASW, and utilizing other shot records with the same receivers compensates for the decreased signal-to-noise ratio. The stacking is realized by summing the [Formula: see text] amplitude spectra of windowed shot records, where windowing produces higher horizontal resolution and stacking produces improved data quality. Mixing is applied between the stacks derived with different parameters, as different frequency ranges require different windowing. SSW was tested and corroborated on a deep seismic data set. Horizontal resolution is validated by [Formula: see text] plots at different frequencies, and [Formula: see text] plots present data quality.
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Sun, Robert, und George A. McMechan. „Depth filtering for one‐component seismic data“. GEOPHYSICS 56, Nr. 9 (September 1991): 1482–85. http://dx.doi.org/10.1190/1.1443169.
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The concept of downward continuation of a seismic wavefield recorded on the earth’s surface to remove near‐surface effects has previously been applied by a number of authors including Schultz and Sherwood (1980), Berryhill (1979, 1984), and McMechan and Chen (1990). Recently, McMechan and Sun (1991) demonstrated, using synthetic elastic data, that downward continuation of an elastic (two‐component) seismic wavefield separates various seismic waves, based on their depth of propagation. This was used to simultaneously remove direct waves and ground roll. The direct compressional and shear waves and the ground roll get left behind in the near surface during downward continuation; subsequent upward continuation reconstructs the surface‐recorded wavefield without the waves propagating in the shallow layers.
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de Groot-Hedlin, Catherine D. „Seismic T-Wave Observations at Dense Seismic Networks“. Seismological Research Letters 91, Nr. 6 (19.08.2020): 3444–53. http://dx.doi.org/10.1785/0220200208.
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Abstract Seismic T waves, which result from transformation of hydroacoustic to seismic energy at coastlines, were investigated for two strong earthquakes. A 2014 Caribbean event generated seismic T waves that were detected at over 250 seismometers along the east coast of the U.S., primarily at seismic stations operated by the USArray Transportable Array. A 2006 Hawaiian event generated seismic T waves observed at over 100 seismometers along the west coast. Seismic T-wave propagation was treated as locally 2D where the incoming hydroacoustic wavefronts were nearly parallel to the coastlines. Along the east coast, seismic T-wave propagation velocities were consistent with surface waves and a polarization analysis indicated that they were transverse waves, supporting their interpretation as Love waves. They were observed at inland distances up to 1134 km from the east coast. Along the west coast, the propagation velocity was over 5 km/s and a polarization analysis confirmed that the seismic T waves propagated as seismic P waves. Differences between the modes of propagation along the east and west coasts are attributed to differences in the slope and thickness of the sediment coverage at the continental slopes where hydroacoustic to seismic conversion takes place.
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Blonk, Bastian, und Gérard C. Herman. „Removal of scattered surface waves using multicomponent seismic data“. GEOPHYSICS 61, Nr. 5 (September 1996): 1483–88. http://dx.doi.org/10.1190/1.1444073.
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In many exploration areas, the shallow subsurface is strongly heterogeneous. The heterogeneities can give rise to scattering of surface waves. These scattered waves can depreciate the quality of land seismic data when they mask the body‐wave reflections from the deeper part of the subsurface. Surface waves scattered near a line of receivers (inline‐scattered waves) can be removed by well‐known filtering techniques (see e.g., Yilmaz, 1987, section 1.6.2). However, surface waves scattered far from the receiver line (crossline‐scattered waves) are left intact partially by filtering because these waves can resemble body‐wave reflections. In previous papers, we have discussed an inverse scattering method for removing scattered surface waves from simulated data (Blonk and Herman, 1994), as well as from field data (Blonk et al., 1995). So far, we have limited our attention to the vertical components of the particle velocity which implies that surface waves and body‐wave reflections can be distinguished on the basis of their respective differences in phase velocity.
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Halliday, David F., Andrew Curtis, Peter Vermeer, Claudio Strobbia, Anna Glushchenko, Dirk-Jan van Manen und Johan O. Robertsson. „Interferometric ground-roll removal: Attenuation of scattered surface waves in single-sensor data“. GEOPHYSICS 75, Nr. 2 (März 2010): SA15—SA25. http://dx.doi.org/10.1190/1.3360948.
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Land seismic data are contaminated by surface waves (or ground roll). These surface waves are a form of source-generated noise and can be strongly scattered by near-surface heterogeneities. The resulting scattered ground roll can be particularly difficult to separate from the desired reflection data, especially when this scattered ground roll propagates in the crossline direction. We have used seismic interferometry to estimate scattered surface waves, recorded during an exploration seismic survey, between pairs of receiver locations. Where sources and receivers coincide, these interreceiver surface-wave estimates were adaptively subtracted from the data. This predictive-subtraction process can successfully attenuate scattered surface waves while preserving the valuable reflected arrivals, forming a new method of scattered ground-roll attenuation. We refer to this as interferometric ground-roll removal.
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O'Neill, A. „Seismic Surface Waves Special Issue Guest Editorial“. Journal of Environmental & Engineering Geophysics 10, Nr. 2 (01.06.2005): 67. http://dx.doi.org/10.2113/jeeg10.2.67.
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Roth, M., K. Holliger und A. G. Green. „Guided waves in near-surface seismic surveys“. Geophysical Research Letters 25, Nr. 7 (01.04.1998): 1071–74. http://dx.doi.org/10.1029/98gl00549.
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Halliday, David, und Andrew Curtis. „Seismic interferometry, surface waves and source distribution“. Geophysical Journal International 175, Nr. 3 (Dezember 2008): 1067–87. http://dx.doi.org/10.1111/j.1365-246x.2008.03918.x.
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22
Levshin, A. L., M. P. Barmin und M. H. Ritzwoller. „Tutorial review of seismic surface waves’ phenomenology“. Journal of Seismology 22, Nr. 2 (07.12.2017): 519–37. http://dx.doi.org/10.1007/s10950-017-9716-7.
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Halliday, David F., Taiwo Fawumi, Johan O. A. Robertsson und Ed Kragh. „On the use of a seismic sensor as a seismic source“. GEOPHYSICS 78, Nr. 5 (01.09.2013): A39—A43. http://dx.doi.org/10.1190/geo2013-0084.1.
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We investigated the use of seismic sensors as small seismic sources. A voltage signal is applied to a geophone that forces the mass within the geophone to move. The movement of the mass generates a seismic wavefield that was recorded with an array of geophones operating in the conventional sense. We observed higher-frequency (25 Hz and above) surface and body waves propagating from the geophone source at offsets of 10 s of meters. We further found that the surface waves emitted from geophone sources can be used to generate a surface-wave group velocity map. We discuss potential developments and future applications.
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Qiu, Xinming, Chao Wang, Jun Lu und Yun Wang. „Surface-Wave Extraction Based on Morphological Diversity of Seismic Events“. Applied Sciences 9, Nr. 1 (21.12.2018): 17. http://dx.doi.org/10.3390/app9010017.
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It is essential to extract high-fidelity surface waves in surface-wave surveys. Because reflections usually interfere with surface waves on X components in multicomponent seismic exploration, it is difficult to extract dispersion curves of surface waves. To make matters worse, the frequencies and velocities of higher-mode surface waves are close to those of PS-waves. A method for surface-wave extraction is proposed based on the morphological differences between surface waves and reflections. Frequency-domain high-resolution linear Radon transform (LRT) and time-domain high-resolution hyperbolic Radon transform (HRT) are used to represent surface waves and reflections, respectively. Then, a sparse representation problem based on morphological component analysis (MCA) is built and optimally solved to obtain high-fidelity surface waves. An advantage of our method is its ability to extract surface waves when their frequencies and velocities are close to those of reflections. Furthermore, the results of synthetic and field examples confirm that the proposed method can attenuate the distortion of surface-wave dispersive energy caused by reflections, which contributes to extraction of accurate dispersion curves.
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Peterie, Shelby L., Julian Ivanov, Erik Knippel, Richard D. Miller und Steven D. Sloan. „Shallow tunnel detection using converted surface waves“. GEOPHYSICS 86, Nr. 3 (01.05.2021): WA59—WA68. http://dx.doi.org/10.1190/geo2020-0357.1.
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Seismic surface waves that were likely converted from incident body waves were used to detect a 3 m deep tunnel using two novel processing methods. In data acquired at a tunnel test site, a unique forward-propagating wave (traveling away from the tunnel and seismic source) was identified as an early-arriving surface wave converted at the tunnel from an incident body wave. To our knowledge, our research represents the first time converted surface waves have been observed originating from a tunnel. We have developed two novel processing methods targeting this unique wavefield component for detecting tunnels, cavities, or other shallow anomalies. The first is a time-domain imaging method that takes advantage of the unique kinematic characteristics of converted surface waves to produce a cross section with a coherent, high-amplitude signature originating from the horizontal location of the tunnel. The second method uses frequency-domain analysis of surface-wave amplitudes, which reveals increased amplitudes (primarily from converted surface waves) at locations expected for the tunnel. These proposed approaches for analysis of converted surface waves were successfully used to detect the tunnel and accurately interpret its horizontal location in real-world data. These novel methods could be the key for detecting shallow tunnels or other subsurface anomalies and complement existing seismic detection methods.
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Chang, Chih‐Hsiung, Gerald H. F. Gardner und John A. McDonald. „Experimental observation of surface wave propagation for a transversely isotropic medium“. GEOPHYSICS 60, Nr. 1 (Januar 1995): 185–90. http://dx.doi.org/10.1190/1.1443745.
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Velocity anisotropy of surface‐wave propagation in a transversely isotropic solid has been observed in a laboratory study. In this study, Phenolite™, an electrical insulation material, was used as the transversely isotropic media (TIM), and a vertical seismic profiling (VSP) geometry was used to record seismic arrivals and to separate surface waves from shear waves. Results show that surface waves that propagate with different velocities exist at certain directions.
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Ardhuin, Fabrice, und T. H. C. Herbers. „Noise generation in the solid Earth, oceans and atmosphere, from nonlinear interacting surface gravity waves in finite depth“. Journal of Fluid Mechanics 716 (25.01.2013): 316–48. http://dx.doi.org/10.1017/jfm.2012.548.
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AbstractOceanic pressure measurements, even in very deep water, and atmospheric pressure or seismic records, from anywhere on Earth, contain noise with dominant periods between 3 and 10 s, which is believed to be excited by ocean surface gravity waves. Most of this noise is explained by a nonlinear wave–wave interaction mechanism, and takes the form of surface gravity waves, acoustic or seismic waves. Previous theoretical work on seismic noise focused on surface (Rayleigh) waves, and did not consider finite-depth effects on the generating wave kinematics. These finite-depth effects are introduced here, which requires the consideration of the direct wave-induced pressure at the ocean bottom, a contribution previously overlooked in the context of seismic noise. That contribution can lead to a considerable reduction of the seismic noise source, which is particularly relevant for noise periods larger than 10 s. The theory is applied to acoustic waves in the atmosphere, extending previous theories that were limited to vertical propagation only. Finally, the noise generation theory is also extended beyond the domain of Rayleigh waves, giving the first quantitative expression for sources of seismic body waves. In the limit of slow phase speeds in the ocean wave forcing, the known and well-verified gravity wave result is obtained, which was previously derived for an incompressible ocean. The noise source of acoustic, acoustic-gravity and seismic modes are given by a mode-specific amplification of the same wave-induced pressure field near zero wavenumber.
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Shin, Changsoo. „Sponge boundary condition for frequency‐domain modeling“. GEOPHYSICS 60, Nr. 6 (November 1995): 1870–74. http://dx.doi.org/10.1190/1.1443918.
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Several techniques have been developed to get rid of edge reflections from artificial boundaries. One of them is to use paraxial approximations of the scalar and elastic wave equations. The other is to attenuate the seismic waves inside the artificial boundary by a gradual reduction of amplitudes. These techniques have been successfully applied to minimize unwanted seismic waves for time‐domain seismic modeling. Unlike time‐domain seismic modeling, suppression of edge reflections from artificial boundaries has not been successful in frequency‐domain seismic modeling. Rayleigh waves caused by coupled motions of P‐ and S‐waves near the surface have been a particularly difficult problem to overcome in seismic modeling. In this paper, I design a damping matrix for frequency‐ domain modeling that damps out seismic waves by adding a diffusion term to the wave equation. This technique can suppress unwanted seismic waves, including Rayleigh waves and P‐ and S‐waves from an artificial boundary.
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Li, Y. G., und P. C. Leary. „Fault zone trapped seismic waves“. Bulletin of the Seismological Society of America 80, Nr. 5 (01.10.1990): 1245–71. http://dx.doi.org/10.1785/bssa0800051245.
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Abstract Two instances of fault zone trapped seismic waves have been observed. At an active normal fault in crystalline rock near Oroville in northern California, trapped waves were excited with a surface source and recorded at five near-fault borehole depths with an oriented three-component borehole seismic sonde. At Parkfield, California, a borehole seismometer at Middle Mountain recorded at least two instances of the fundamental and first higher mode seismic waves of the San Andreas fault zone. At Oroville recorded particle motions indicate the presence of both Love and Rayleigh normal modes. The Love-wave dispersion relation derived for an idealized wave guide with velocity structure determined by body-wave travel-time inversion yields seismograms of the fundamental mode that are consistent with the observed Love-wave amplitude and frequency. Applying a similar velocity model to the Parkfield observations, we obtain a good fit to the trapped wavefield amplitude, frequency, dispersion, and mode time separation for an asymmetric San Andreas fault zone structure—a high-velocity half-space to the southwest, a low-velocity fault zone, a transition zone containing the borehole seismometer, and an intermediate velocity half-space to the northeast. In the Parkfield borehole seismic data set, the locations (depth and offset normal to fault plane) of natural seismic events which do or do not excite trapped waves are roughly consistent with our model of the low velocity zone. We conclude that it is feasible to obtain near-surface borehole records of fault zone trapped waves. Because trapped modes are excited only by events close to the fault zone proper—thereby fixing these events in space relative to the fault—a wider investigation of possible trapped mode waveforms recorded by a borehole seismic network could lead to a much refined body-wave/tomographic velocity model of the fault and to a weighting of events as a function of offset from the fault plane. It is an open question whether near-surface sensors exist in a stable enough seismic environment to use trapped modes as an earth monitoring device.
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Fang, Jie, Yu Liu und Guofeng Liu. „Enhancing body waves in passive seismic reflection exploration: A case study in Inner Mongolia, China“. Interpretation 10, Nr. 2 (11.04.2022): B13—B24. http://dx.doi.org/10.1190/int-2021-0113.1.
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Among all geophysical exploration methods, seismic exploration is undoubtedly the most important due to its ability to allow depth exploration at high resolutions. Traditionally speaking, the method needs an active seismic source, such as dynamite, to generate energy and perform reflection and refractions. An active source usually means high cost, and it also can be quite difficult to implement when surface conditions are particularly complex. The use of passive seismic for reflection exploration does not require an active seismic source. It has the potential of providing a low-cost alternative technique in some exploration areas. The main issues related to passive-source body-wave exploration include suppressing the surface waves retrieved from sources located at or near the surface, as well as enhancing the body waves from random sources at depth. We address these problems by developing a preprocessing workflow to suppress the surface waves and the other unwanted coherent noise events in the original data without seriously affecting the remaining body waves. We also propose a method for separating surface and body waves based on the signal-to-noise ratio of the frequency-domain signals. Next, we use crosscorrelation to generate virtual shot gathers, just like the active ones, and use conventional seismic data processing steps to generate the final seismic imaging. By analyzing the passive data set collected from Inner Mongolia, we have verified the applicability of the proposed method, and the retrieved final stack section indicates good consistency with an active seismic stack section along the same line. Accordingly, we assert that the application of this data processing method will contribute to the body-wave imaging and the inversion analysis of passive seismic records.
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Zaitsev, Dmitry, Vitaliy Bryksin, Konstantin Belotelov, Yulia Kompaniets und Roman Iakovlev. „Algorithms and Measuring Complex for Classification of Seismic Signal Sources, Determination of Distance and Azimuth to the Point of Excitation of Surface Waves“. Informatics and Automation 21, Nr. 6 (24.11.2022): 1211–39. http://dx.doi.org/10.15622/ia.21.6.5.
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Machine learning and digital signal processing methods are used in various industries, including in the analysis and classification of seismic signals from surface sources. The developed wave type analysis algorithm makes it possible to automatically identify and, accordingly, separate incoming seismic waves based on their characteristics. To distinguish the types of waves, a seismic measuring complex is used that determines the characteristics of the boundary waves of surface sources using special molecular electronic sensors of angular and linear oscillations. The results of the algorithm for processing data obtained by the method of seismic observations using spectral analysis based on the Morlet wavelet are presented. The paper also describes an algorithm for classifying signal sources, determining the distance and azimuth to the point of excitation of surface waves, considers the use of statistical characteristics and MFCC (Mel-frequency cepstral coefficients) parameters, as well as their joint application. At the same time, the following were used as statistical characteristics of the signal: variance, kurtosis coefficient, entropy and average value, and gradient boosting was chosen as a machine learning method; a machine learning method based on gradient boosting using statistical and MFCC parameters was used as a method for determining the distance to the signal source. The training was conducted on test data based on the selected special parameters of signals from sources of seismic excitation of surface waves. From a practical point of view, new methods of seismic observations and analysis of boundary waves make it possible to solve the problem of ensuring a dense arrangement of sensors in hard-to-reach places, eliminate the lack of knowledge in algorithms for processing data from seismic sensors of angular movements, classify and systematize sources, improve prediction accuracy, implement algorithms for locating and tracking sources. The aim of the work was to create algorithms for processing seismic data for classifying signal sources, determining the distance and azimuth to the point of excitation of surface waves.
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Ungureanu, Bogdan, Sebastien Guenneau, Younes Achaoui, Andre Diatta, Mohamed Farhat, Harsha Hutridurga, Richard V. Craster, Stefan Enoch und Stephane Brûlé. „The influence of building interactions on seismic and elastic body waves“. EPJ Applied Metamaterials 6 (2019): 18. http://dx.doi.org/10.1051/epjam/2019015.
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We outline some recent research advances on the control of elastic waves in thin and thick plates, that have occurred since the large scale experiment [S. Brûlé, Phys. Rev. Lett. 112, 133901 (2014)] that demonstrated significant interaction of surface seismic waves with holes structuring sedimentary soils at the meter scale. We further investigate the seismic wave trajectories of compressional body waves in soils structured with buildings. A significant substitution of soils by inclusions, acting as foundations, raises the question of the effective dynamic properties of these structured soils. Buildings, in the case of perfect elastic conditions for both soil and buildings, are shown to interact and strongly influence elastic body waves; such site-city seismic interactions were pointed out in [Guéguen et al., Bull. Seismol. Soc. Am. 92, 794–811 (2002)], and we investigate a variety of scenarios to illustrate the variety of behaviours possible.
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Ernst, Fabian E., Gérard C. Herman und Auke Ditzel. „Removal of scattered guided waves from seismic data“. GEOPHYSICS 67, Nr. 4 (Juli 2002): 1240–48. http://dx.doi.org/10.1190/1.1500386.
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Near‐surface scattered waves form a major source of coherent noise in seismic land data. Most current methods for removing these waves do not attenuate them adequately if they come from other than the inline direction. We present a wave‐theory‐based method for removing (scattered) guided waves by a prediction‐and‐removal algorithm. We assume that the near surface consists of a laterally varying medium, in which heterogeneities are embedded that act as scatterers. We first estimate the dispersive and laterally varying phase slowness field by applying a phase‐based tomography algorithm on the direct groundroll wave. Subsequently, the near‐surface heterogeneities are imaged using a least‐squares criterium. Finally, the scattered guided waves are modeled and subtracted adaptively from the seismic data. We have applied this method to seismic land data and found that near‐surface scattering effects are attenuated.
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Xu, Hao, Xinjiang Yu, Fei Cheng, Yuxi Ma, Jialiang Li und Xiaohuan Jiang. „Effects of Earth–Rock Dam Heterogeneity on Seismic Wavefield Characteristics“. Energies 16, Nr. 5 (03.03.2023): 2423. http://dx.doi.org/10.3390/en16052423.
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Earth–rock dams are typical soil–rock mixtures with high heterogeneity. Mastering the effect of dam heterogeneity on seismic wavefields is the premise of accurately detecting hidden risks in dams. In this paper, based on the soil–rock mixture characteristics of actual dams, a soil–rock mixture model that can reflect the heterogeneity of dams is established through local segmentation and reassignment of random disturbances. The influence of local area size on model heterogeneity is described. The seismic wavefield in a soil–rock mixture dam is numerically simulated through a staggered-grid finite-difference algorithm with second-order accuracy in time and sixth-order accuracy in space. Then, the effect of dam heterogeneity on effective wavefields is analyzed. The results show that the heterogeneity of the earth–rock dam can lead to scattered waves in the seismic wavefield, and the scattered waves are mainly generated by Rayleigh surface waves. In the seismic record, scattered waves with strong energy appear in the region below the surface waves. The scattered wave energy is weak and close to that in the homogeneous media in the region above the surface waves. As the rock content in the dam increases, the scattering of seismic wavefields and the energy of scattered waves weaken gradually. The scattered waves generated by the heterogeneity of the dam significantly impact the reflected longitudinal wave and converted wave but, affect the reflected shear wave less. The numerical simulation results are consistent with the acquired seismic wavefield from the field test, proving the effectiveness of the numerical simulation for the seismic wavefield propagation characteristics of the earth–rock dam.
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Ji-Xiang, XU. „Separating the Near-Surface Seismic Scattered Waves Using Seismic Interferometry Method“. Chinese Journal of Geophysics 57, Nr. 4 (Juli 2014): 574–90. http://dx.doi.org/10.1002/cjg2.20125.
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Apostol, Bogdan Felix. „Site effects in seismic motion“. Journal of AppliedMath 3, Nr. 1 (15.01.2025): 1593. https://doi.org/10.59400/jam1593.
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We use the harmonic-oscillator model to analyze the motion of the sites (ground motion), seimograph recordings, and structures built on the Earth’s surface under the action of the seismic motion. The seismic motion consists of singular waves (spherical-shell P and S primary seismic waves) and discontinuous (step-wise) seismic main shocks. It is shown that these singularities and discontinuities are present in the ground motion, seismographs’ recordings and the motion of the built structures. In addition, the motion of the oscillator exhibits oscillations with its own eigenfrequency, which represent the response of the oscillator to external perturbations. We estimate the peak values of the displacement, the velocity and the acceleration of the ground motion, both for the seismic waves and the main shock, which may be used as input parameters for seismic hazard studies. We discuss the parameters entering these formulae, like the dimension of the earthquake focus, the width of the primary waves and the eigenfrequencies of the site. The width of the seismic waves on the Earth’s surface, which includes the energy loss, can be identified from the Fourier spectrum of the seismic waves. Similarly, the eigenfrequencies of the site can be identified from the spectrum of the site response. The paper provides a methodology for estimating the input parameters used in hazard studies.
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Cameron, Antonio E., und Camelia C. Knapp. „A New Approach to Predict Hydrogeological Parameters Using Shear Waves from the Multichannel Analysis of Surface Waves Method“. Journal of Environmental and Engineering Geophysics 26, Nr. 3 (September 2021): 195–208. http://dx.doi.org/10.32389/jeeg21-008.
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For near-surface contaminant characterization, the accurate prediction of hydrogeological parameters in anisotropic and heterogeneous environments has been a challenge since the last decades. However, recent advances in near-surface geophysics have facilitated the use of geophysical data for hydrogeological characterization in the last few years. A pseudo 3-D high resolution P-wave shallow seismic reflection survey was performed at the P Reactor Area, Savannah River Site, South Carolina in order to delineate and predict migration pathways of a large contaminant plume including trichloroethylene. This contaminant plume originates from the northwest section of the reactor facility that is located within the Upper Atlantic Coastal Plain. The data were collected with 40 Hz geophones, an accelerated weight-drop as seismic source and 1 m receiver spacing with near- and far-offsets of 0.5 and 119.5 m, respectively. In such areas with near-surface contaminants, a detailed subsurface characterization of the vadose zone hydraulic parameters is very important. Indeed, an inexpensive method of deriving such parameters by the use of seismic reflection surveys is beneficial, and our approach uses the relationship between seismic velocity and hydrogeological parameters together with empirical observations relating porosity to permeability and hydraulic conductivity. Shear wave velocity ( Vs) profiles were estimated from surface wave dispersion analysis of the seismic reflection data and were subsequently used to derive hydraulic parameters such as porosity, permeability, and hydraulic conductivity. Additional geophysical data including core samples, vertical seismic profiling, surface electrical resistivity tomography, natural gamma and electrical resistivity logs allowed for a robust assessment of the validity and geological significance of the estimated Vs and hydrogeological models. The results demonstrate the usefulness of this approach for the upper 15 m of shallow unconsolidated sediments even though the survey design parameters were not optimal for surface wave analysis due to the higher than desired frequency geophones.
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Talandier, Jacques, und Emile A. Okal. „On the mechanism of conversion of seismic waves to and from T waves in the vicinity of island shores“. Bulletin of the Seismological Society of America 88, Nr. 2 (01.04.1998): 621–32. http://dx.doi.org/10.1785/bssa0880020621.
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Abstract High-frequency seismic records from the Polynesian Seismic Network are used to investigate in detail the processes of conversion of acoustic (T-wave) energy from and to seismic waves at island shores. On the source side, we study the seismic-to-acoustic conversion based on T phases from Hawaiian events recorded at Polynesian stations located on the coral platter; on the receiver side, we study the acoustic-to-seismic conversion based on T phases from marine sources recorded across the Polynesian islands. In both instances, our results underline the importance of steep slopes (typically 50°) in allowing an efficient conversion between P waves in the island structure and T waves in the water column. These slopes can be coral reefs or the heads of young, presumably unconsolidated, basalt flows. Under this geometry, modeling based on raytracing indicates that the seismic record of the T phase consists of a P wave at distances from the conversion point greater than 9 km; at shorter distances, S waves and surface waves are generated. In the absence of a steep slope, only surface waves are present. These models can be used to compute precise and predictable travel-time station corrections, allowing the use of seismometers located inland to exploit the superb detection and location capabilities of T waves.
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Blonk, Bastian, Gerard C. Herman und Guy G. Drijkoningen. „An elastodynamic inverse scattering method for removing scattered surface waves from field data“. GEOPHYSICS 60, Nr. 6 (November 1995): 1897–905. http://dx.doi.org/10.1190/1.1443921.
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In an earlier paper, we introduced a 3-D inverse scattering method for removing scattered surface waves from seismic data that was based on a tomographic imaging of the scattered surface waves by a data‐fitting procedure that used as much of the seismic data as possible. After this imaging step, the scattered surface waves can be computed and removed for each separate source‐receiver pair. We now apply the method to two field‐data sets. The method requires a knowledge of the source waveform and shallow propagation characteristics, and these input requirements are estimated from the direct surface wave. We conclude that the method effectively attenuates crossline scattered surface waves without affecting deeper reflections.
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Cao, Haitao, Erdi Apatay, Garvie Crane, Boming Wu, Ke Gao und Roohollah Askari. „Evaluation of Various Data Acquisition Scenarios for the Retrieval of Seismic Body Waves from Ambient Noise Seismic Interferometry Technique via Numerical Modeling“. Geosciences 12, Nr. 7 (02.07.2022): 270. http://dx.doi.org/10.3390/geosciences12070270.
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Seismic interferometry is often proposed as a cost-efficient technique for reservoir monitoring including CO2 sequestration due to its low cost and environmental advantages over active source imaging. Although many studies have demonstrated the ability of seismic interferometry to retrieve surface waves, body wave imaging remains challenging due to their generally lower amplitudes of body waves in seismic interferometry data. An optimum data acquisition strategy can help retrieve low amplitude body waves better, however, rare attempts have been made to evaluate various data acquisition strategies. In this study, we use numerical modeling to examine three different acquisition schemes to evaluate the retrievability of P waves from seismic interferometry data. From our numerical results, we observe that (1) positing receivers beneath the attenuated weathered layer improves the data quality and signal to noise ratio, but additional processing steps including predictive deconvolution and Radom transform filter are necessary to remove the downgoing surface multiples, artifacts that are generated from this data acquisition; (2) vertical seismic profiling (VSP) alongside with the conventional surface seismic acquisition improve the target zone detection; and (3) crosswell acquisition of seismic interferometry is an ineffective means to obtain reflection events due to the non-similarity of ray paths from the noise sources meaning that the required stationary phase theory is not fulfilled.
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Schuster, Gerard T., Jing Li, Kai Lu, Ahmed Metwally, Abdullah AlTheyab und Sherif Hanafy. „Opportunities and pitfalls in surface-wave interpretation“. Interpretation 5, Nr. 1 (01.02.2017): T131—T141. http://dx.doi.org/10.1190/int-2016-0011.1.
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Many explorationists think of surface waves as the most damaging noise in land seismic data. Thus, much effort is spent in designing geophone arrays and filtering methods that attenuate these noisy events. It is now becoming apparent that surface waves can be a valuable ally in characterizing the near-surface geology. This review aims to find out how the interpreter can exploit some of the many opportunities available in surface waves recorded in land seismic data. For example, the dispersion curves associated with surface waves can be inverted to give the S-wave velocity tomogram, the common-offset gathers can reveal the presence of near-surface faults or velocity anomalies, and back-scattered surface waves can be migrated to detect the location of near-surface faults. However, the main limitation of surface waves is that they are typically sensitive to S-wave velocity variations no deeper than approximately half to one-third the dominant wavelength. For many exploration surveys, this limits the depth of investigation to be no deeper than approximately 0.5–1.0 km.
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Shearer, P. M., und J. A. Orcutt. „Surface and near-surface effects on seismic waves—theory and borehole seismometer results“. Bulletin of the Seismological Society of America 77, Nr. 4 (01.08.1987): 1168–96. http://dx.doi.org/10.1785/bssa0770041168.
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Abstract A simple plane wave model is adequate to explain many surface versus borehole seismometer data sets. Using such a model, we present a series of examples which demonstrate the effects of the free-surface, near-surface velocity gradients, and low impedance surface layers on the amplitudes of upcoming body waves. In some cases, these amplitudes are predictable from simple free-surface and impedance contrast expressions. However, in other cases these expressions are an unreliable guide to the complete response, and the full plane wave calculation must be performed. Large surface amplifications are possible, even without focusing due to lateral heterogeneities or nonlinear effects. Both surface and borehole seismometer site responses are almost always frequency-dependent. Ocean bottom versus borehole seismic data from the 1983 Ngendei Seismic Experiment in the southwest Pacific are consistent with both a simple plane wave model and a more complete synthetic seismogram calculation. The borehole seismic response to upcoming P waves is reduced at high frequencies because of interference between the upgoing P wave and downgoing P and SV waves reflected from the sediment-basement interface. However, because of much lower borehole noise levels, the borehole seismometer enjoys a P-wave signal-to-noise advantage of 3 to 7 dB over nearby ocean bottom instruments.
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Zhang, Weihua, Li Yang, Wenpeng Si und Houyu Liu. „Seismic wave simulation of a complex foothill belt“. Journal of Geophysics and Engineering 17, Nr. 5 (04.08.2020): 893–905. http://dx.doi.org/10.1093/jge/gxaa038.
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Abstract Foothill belts ‘dual-complexity’ of the surface and underground structures hinders an accurate seismic imaging of complex geological structures. In this paper, the propagation law of the seismic wavefield in the foothill belt is studied through seismic forward modelling and its influences on the seismic data acquisition and imaging. A foothill belt with typical ‘dual-complexity’ characteristics is investigated. Single-shot records and their imaging effects simulated with different absorption coefficients and different near-surface structure models are analysed. The results suggest that strong surface waves and their scattered noise generated by the complex near surface in the foothill belt are the main reasons for the low signal-to-noise ratio and difficulties in the imaging process of seismic data. The viscoelastic-medium modelling method effectively suppresses the surface waves and their scattered noise, which improves the seismic data quality and imaging in the foothill belt, and thus is a suitable forward modelling method for the foothill belts.
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Campman, Xander H., Gérard C. Herman und Everhard Muyzert. „Suppressing near-receiver scattered waves from seismic land data“. GEOPHYSICS 71, Nr. 4 (Juli 2006): S121—S128. http://dx.doi.org/10.1190/1.2204965.
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Upgoing body waves that travel through a heterogeneous near-surface region can excite scattered waves. When the scattering takes place close to the receivers, secondary waves interfere with the upcoming reflections, diminishing the continuity of the wavefront. We estimate a near-surface scattering distribution from a subset of a data record and use this scattering distribution to predict the secondary waves of the entire data record with a wave-theoretical model for near-receiver scattering. We then subtract the predicted scattered waves from the record to obtain the wavefield that would have been measured in the absence of near-surface heterogeneities. We apply this method to part of a field data set acquired in an area with significant near-surface heterogeneity. The main result of our processing scheme is that we effectively remove near-surface scattered waves. This, in turn, increases trace-to-trace coherence of reflection events. Moreover, application of our method improves the results obtained from just an application of a dip filter because we remove parts of the scattered wave with apparent velocities that are typically accepted by the pass zone of the dip filter. Based on these results, we conclude that our method for suppressing near-receiver scattered waves works well on densely sampled land data collected in areas with strong near-surface heterogeneity.
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Meng, Xiangyu, Fuxing Han, Jianguo Sun, Mingchen Liu, Zeshuang Xu und Mingyang Lv. „Calculating multiple scattering from a time-varying undulating sea surface using a full-wavefield multistage algorithm“. GEOPHYSICS 87, Nr. 2 (27.01.2022): T123—T133. http://dx.doi.org/10.1190/geo2020-0563.1.
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The sea-surface interface between ocean and air is time varying and can be spatially rough as a result of wind, tides, and currents; the shape of this interface changes over time under the influence of wind, tides, etc. As a result, waves impinging on the sea surface are continuously scattered. In the case of marine seismic, the multiple-scattered waves propagate downward into the underwater formation and result in complex seismic responses. To understand the structure of the responses, we have adopted a multistage algorithm for computing the scattered waves at the sea surface. Specifically, we first extrapolate the upgoing incident waves stepwise using thin-slab approximation from the scattering theory based on the De Wolf approximation of the Lippmann-Schwinger equation. Then, we implement the air-water boundary condition at the sea surface. Finally, we use the irregular boundary processing technique to compute the time-varying undulating sea-surface scattered waves from different scattering stages. To overcome the angular limitation of the original parabolic approximation, we introduce a multidirectional parabolic approximation based on computational electromagnetics. Numerical tests indicate that the multistage algorithm presented here can accurately calculate sea-surface scattered waves and should be useful in investigating the structure of marine seismic responses.
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Hong, Seokgyeong, und Jaehun Ahn. „Seismic Ground Response Analysis Based on Multilayer Perceptron and Convolution Neural Networks“. Journal of the Korean Society of Hazard Mitigation 21, Nr. 1 (28.02.2021): 231–38. http://dx.doi.org/10.9798/kosham.2021.21.1.231.
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The importance of establishing a disaster prevention plan considering seismic performance is being highlighted to reduce damage to structures caused by earthquakes. Earthquake waves propagate from the bedrock to the ground surface through the soil. During the transmission process, they are amplified in a specific frequency range, and the degree of amplification depends mainly on the characteristics of the ground. Therefore, a seismic response analysis process is essential for enhancing the reliability of the seismic design. We propose a model for predicting seismic waves on the surface from seismic waves measured on the bedrock based on Multilayer Perceptron (MLP) and Convolutional Neural Networks (CNN) and validate the applicability of the proposed model with Spectral Acceleration (SA). Both the proposed models based on MLP and CNN successfully predicted the seismic response of the surface. The CNN-based model performed better than the MLP-based model, with a 10% smaller average error. We plan to implement the physical properties of the ground, such as shear wave velocity, to create a more versatile model in the future.
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Kritski, A., A. P. Vincent, D. A. Yuen und T. Carlsen. „Adaptive wavelets for analyzing dispersive seismic waves“. GEOPHYSICS 72, Nr. 1 (Januar 2007): V1—V11. http://dx.doi.org/10.1190/1.2374799.
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Our primary objective is to develop an efficient and accurate method for analyzing time series with a multiscale character. Our motivation stems from the studies of the physical properties of marine sediment (stiffness and density) derived from seismic acoustic records of surface/interface waves along the water-seabed boundary. These studies depend on the dispersive characteristics of water-sediment surface waves. To obtain a reliable retrieval of the shear-wave velocities, we need a very accurate time-frequency record of the surface waves. Such a time-frequency analysis is best carried out by a wavelet-transform of the seismic records. We have employed the wavelet crosscorrelation technique for estimating the shear-wave propagational parameters as a function of depth and horizontal distance. For achieving a greatly improved resolution in time-frequency space, we have developed a new set of adaptive wavelets, which are driven by the data. This approach is based on a Karhunen-Loeve (KL) decomposition of the seismograms. This KL decomposition allows us to obtain a set of wavelet functions that are naturally adapted to the scales of the surface-wave modes. We demonstrate the superiority of these adaptive wavelets over standard wavelets in their ability to simultaneously discriminate the different surface-wave modes. The results can also be useful for imaging and statistical data analysis in exploration geophysics and in other disciplines in the environmental sciences.
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Kaçın, Selcuk, Murat Özturk, Umur Korkut Sevim, Muharrem Karaaslan, Oğuzhan Akgöl, Zafer Özer, Mustafa Demirci et al. „Prevention of Wave Propagation via Circular Arrangement of Seismic Metamaterials Formed with Concrete Piles“. Symmetry 15, Nr. 8 (27.07.2023): 1489. http://dx.doi.org/10.3390/sym15081489.
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It is known that the low frequencies of seismic surface waves have a destructive effect. The main purpose of seismic metamaterials is to protect structures from seismic waves at low frequencies, especially in a wide band. In this study, the effects of seismic metamaterials formed using circular array concrete piles on surface waves were investigated. Each concrete pile has been selected due to symmetric properties to investigate the band diagram. Therefore, the direction independence can also be determined with respect to frequency. This study was conducted both numerically and experimentally in the low-frequency range of 5–15 Hz. Two fields, with and without metamaterials, have been designed and compared. In numerical analysis, transmission loss graphs were drawn using the finite element method (FEM), and wave propagation at frequencies where the loss happened was simulated. In numerical analysis, optimum dimensions such as radius and depth were determined, and these dimensions were applied exactly in the experimental field. The results obtained from the experiment using a harmonic vibration device are mapped. In this numerical and experimental study, it has been revealed that the proposed structure prevents the propagation of seismic surface waves.
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Campman, Xander, und Christina Dwi Riyanti. „Non-linear inversion of scattered seismic surface waves“. Geophysical Journal International 171, Nr. 3 (14.09.2007): 1118–25. http://dx.doi.org/10.1111/j.1365-246x.2007.03557.x.
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Donohue, Shane, Dermot Forristal und Louise A. Donohue. „Detection of soil compaction using seismic surface waves“. Soil and Tillage Research 128 (April 2013): 54–60. http://dx.doi.org/10.1016/j.still.2012.11.001.
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