Journal articles: 'Synthethic seismograms'

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Davidson, Mark E., and Lawrence W. Braile. "Vibroseis recording techniques and data reduction from the Jemez Tomography Experiment." Bulletin of the Seismological Society of America 89, no. 5 (October 1, 1999): 1352–65. http://dx.doi.org/10.1785/bssa0890051352.

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Abstract The Jemez Tomography Experiment (JTEX) is a multidisciplinary study focused on the Valles Caldera and the Jemez Mountains, New Mexico. The objectives of the project are to create a high resolution crustal model of the subsurface structure of this silicic volcanic system and to develop an interpretation of its volcanic evolution. Use of Vibroseis sources in the acquisition of refraction/wide-angle reflection seismic data provided challenges beyond conventional explosive-source data. Processing of the JTEX Vibroseis data is an involved procedure consisting of sorting, cross-correlating, filtering, and stacking numerous individual seismograms in the production of final record sections. However, excellent results (high signal-to-noise seismograms at relatively small spacings) are obtainable with coherent arrivals at source-receiver distances of more than 60 km. The primary drawback in this approach lies in the massive volume of data that is necessary to produce record sections. One benefit of the Vibroseis source used during JTEX was a method to decrease effective seismogram spacing. This technique, dubbed a “source-offset” technique, provides smaller overall seismograph station spacing by moving the Vibroseis sources during acquisition and leaving deployed seismographs stationary. After station corrections, this method effectively decreases station spacings and increases detail in resulting record sections. Various shallow crustal heterogeneities create travel-time advances and delays that affect the source-offset data differently than single-source data. Synthetic modeling demonstrates small travel-time discrepancies associated with the source-offset technique. However, the addition of traces with smaller station intervals clarifies secondary arrivals within record sections and aids in interpretation of these arrivals with a minimum amount of field effort required.

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Gutowski, P. R., and S. Treitel. "The generalized one‐dimensional synthetic seismogram." GEOPHYSICS 52, no. 5 (May 1987): 589–605. http://dx.doi.org/10.1190/1.1442329.

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The normal‐incidence synthetic seismogram for an elastic and horizontally stratified medium has been thoroughly studied for a relatively restricted number of source and receiver locations. Most existing treatments are concerned with the special case in which the source as well as the receiver are situated at the surface; few attempts have dealt with completely arbitrary source and receiver geometries. Here we examine arbitrary geometries with the aid of the layer matrix approach, in which upgoing and downgoing wave motion at each interface is expressed in terms of z-transform polynomials. Such an approach brings to light a number of physically important relations that the model satisfies. For example, the synthetic seismograms generally have the familiar autoregressive‐moving average (ARMA) structure for the surface‐source, surface‐receiver case. For particular combinations of reflection coefficients, however, the seismograms reduce to purely autoregressive (AR) representations. In all cases, we work out the delay properties that the respective autoregressive and moving average components must obey. The present solutions are easily reduced to a useful form for practical computation. One application of particular current interest is the simulation of vertical seismic profiling (VSP) surveys, where we have extended the theoretical treatment to include expressions for the derivatives of the seismograms with respect to the reflection coefficients. The resulting time series, which we call Jacobograms, are indicative of the sensitivity of the seismogram to the various reflection coefficients and are thus diagnostic of the model’s behavior.

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Isaac, J. Helen, and Don C. Lawton. "A case study showing the value of multioffset synthetic seismograms in seismic data interpretation." Interpretation 4, no. 4 (November 1, 2016): T455—T459. http://dx.doi.org/10.1190/int-2016-0036.1.

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A baseline 3D3C seismic survey was acquired in May 2014 at a Field Research Station in Southern Alberta, Canada, which is the site of experimental [Formula: see text] injection into an Upper Cretaceous sandstone at approximately 300 m depth. We have created synthetic seismograms from sonic and density logs to identify reflectors seen on the processed seismic data. The high-amplitude positive response (peak) at the top of the Upper Cretaceous Milk River Formation sandstone on the normal incidence PP synthetic seismogram does not match the response seen on the migrated PP seismic data, which is a very low amplitude peak. For such a high impedance, low Poisson’s ratio sandstone, the Zoeppritz equations predict a high-amplitude reflection coefficient at zero offset, then a decrease in amplitude, and even a change in polarity with increasing source-receiver offset. To match the stacked seismic data better, we have created offset synthetic seismograms using P- and S-wave sonic logs and density logs. The character of the top Milk River reflection on the seismic data stacked using all offset traces resembles that observed on the stacked offset synthetic seismogram, which is a similar low-amplitude peak. The character of the top Milk River reflection on the seismic data stacked using only near-offset traces to 250 m looks like that seen on the normal incidence synthetic seismogram.

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Langston, Charles A., and Chang-Eob Baag. "The validity of ray theory approximations for the computation of teleseismic SV waves." Bulletin of the Seismological Society of America 75, no. 6 (December 1, 1985): 1719–27. http://dx.doi.org/10.1785/bssa0750061719.

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Abstract Teleseismic SV waves have been generally ignored in wave propagation and source studies because of known complications in wave propagation for structure near the source and near the receiver. The validity of common optic ray and WKBJ seismogram methods for computing SV synthetic seismograms is examined by computing synthetic seismograms using these techniques and comparing them to SV synthetics produced from a wavenumber integration technique. Both ray methods give a poor approximation to the wave propagation for distances less than 60°. Diffracted Sp and the SPL wave interfere with near-source phases, such as S, pS, and sS for a shallow seismic source, producing anomalously high amplitudes and complex waveforms in agreement with observational experience. Because of the Moho Sp and diffracted Sp phases, the vertical component of motion shows greater distortion, relative to the ray theory result, than does the radial component of motion. Ray theory appears to be appropriate for the initial 20 sec of the SV wave train from a shallow source for ranges greater than 60°. SV waves from deep sources are less affected by diffracted Sp and SPL than SV from shallow sources.

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SANTOSA, BAGUS JAYA. "S WAVE VELOCITY STRUCTURE IN NONTECTONIC SE ASIA BY SEISMOGRAM ANALYSIS OF THE EARTHQUAKES IN SUMATRA–JAVA AT TATO STATION, TAIWAN." Journal of Earthquake and Tsunami 04, no. 03 (September 2010): 181–95. http://dx.doi.org/10.1142/s1793431110000911.

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The S wave velocity structure beneath South-East Asia and South China Sea due to earthquakes in Sumatra–Java subduction zone has been investigated through seismogram analysis in time domain and three components simultaneously, using data recorded in TATO, Taiwan seismological station. The synthetic seismogram was calculated using the GEMINI method, which consists of the earth model and the CMT solution of the earthquake. A low-pass filter with corner frequency of 20 mHz is imposed to the seismograms. Response file inversion subjected on the measured seismogram will compare the measured and the synthetic seismogram in the same unit. The seismogram comparison indicated that the synthetic seismogram constructed from PREMAN earth model deviates greatly from the measured one. The deviation occurred on the arrival time of surface wave of Rayleigh and Love as well as S body waves. The S, Love, and Rayleigh waveform deviations on arrival time or oscillation number are solved by changing the gradient of βh into positive in the upper mantle layers, and corrections for zero-order coefficients of β speed polynomial in every earth mantle layers. The interpretation results of seismogram analysis using waveform comparison indicate that the nontectonic South-East Asia area in front of subduction zone has strong negative correction of βv in the upper mantle and with smaller factor also at earth layers below. This result shows stronger vertical anisotropy than that indicated by the PREMAN earth model.

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Sun, Robert, George A. McMechan, Hsu‐Hong Hsiao, and Jinder Chow. "Separating P‐ and S‐waves in prestack 3D elastic seismograms using divergence and curl." GEOPHYSICS 69, no. 1 (January 2004): 286–97. http://dx.doi.org/10.1190/1.1649396.

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The reflected P‐ and S‐waves in a prestack 3D, three‐component elastic seismic section can be separated by taking the divergence and curl during finite‐difference extrapolation. The elastic seismic data are downward extrapolated from the receiver locations into a homogeneous elastic computational model using the 3D elastic wave equation. During downward extrapolation, divergence (a scalar) and curl (a three‐component vector) of the wavefield are computed and recorded independently, at a fixed depth, as a one‐component seismogram and a three‐component seismogram, respectively. The P‐ and S‐velocities in the elastic computational model are then split into two independent models. The divergence seismogram (containing P‐waves only) is then upward extrapolated (using the scalar wave equation) through the P‐velocity model to the original receiver locations at the surface to obtain the separated P‐waves. The x‐component, y‐component, and z‐component seismograms of the curl (containing S‐waves only) are upward extrapolated independently (using the scalar wave equation) through the S‐velocity model to the original receiver locations at the surface to obtain the separated S‐waves. Tests are successful on synthetic seismograms computed for simple laterally heterogeneous 2D models with a 3D recording geometry even if the velocities used in the extrapolations are not accurate.

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Kwak, Sangmin, Hyunggu Jun, Wansoo Ha, and Changsoo Shin. "Temporal windowing and inverse transform of the wavefield in the Laplace-Fourier domain." GEOPHYSICS 78, no. 5 (September 1, 2013): R207—R222. http://dx.doi.org/10.1190/geo2012-0249.1.

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Temporal windowing is a valuable process, which can help us to focus on a specific event in a seismogram. However, applying the time window is difficult outside the time domain. We suggest a windowing method which is applicable in the Laplace-Fourier domain. The window function we adopt is defined as a product of a gain function and an exponential damping function. The Fourier transform of a seismogram windowed by this function is equivalent to the partial derivative of the Laplace-Fourier domain wavefield with respect to the complex damping constant. Therefore, we can obtain a windowed seismogram using the partial derivatives of the Laplace-Fourier domain wavefield. We exploit the time-windowed wavefield, which is modeled directly in the Laplace-Fourier domain, to reconstruct subsurface velocity model by waveform inversion in the Laplace-Fourier domain. We present the windowed seismograms by introducing an inverse Laplace-Fourier transform technique and demonstrate the effect of temporal windowing in a synthetic Laplace-Fourier domain waveform inversion example.

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SANTOSA, BAGUS JAYA. "INVESTIGATING S VELOCITY STRUCTURE OF THE UPPER MANTLE BENEATH WEST INDONESIA USING SEISMOGRAM ANALYSIS OF TWO STRONG SOUTH JAVA EARTHQUAKES IN MALAYSIAN SEISMOLOGICAL NETWORK." Journal of Earthquake and Tsunami 04, no. 04 (December 2010): 321–39. http://dx.doi.org/10.1142/s1793431110000881.

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This research investigated the S speed structure in the upper mantle beneath West Indonesia by analyzing the seismogram triggered by the C052606A and C071706B earthquakes in South Java and recorded at the Malaysian seismological network MY. The method used is waveform comparison between the measured seismogram and the synthetic one in the time domain and three Cartesian components simultaneously, instead of travel time data or dispersion curve, which are commonly used by other seismologists. The seismogram comparison was conducted in the same unit and a low-pass filter with 20 mHz corner frequency was applied to both seismograms. Seismogram analysis shows very strong deviations in the arrival times and amplitudes of the Love and Rayleigh surface waveforms. To solve the observed deviation, a correction on the earth structure covering the speed gradient of βh and the value of zero-order coefficients for the βh and βv in the earth upper mantle is required. The research's result shows that the area of East Sumatra and Borneo has negative correction of S speed structure in the upper mantle layers, compared to PREMAN standard earth model. This result is different from other seismological result.

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Cheng, Guangsen, Xingyao Yin, Zhaoyun Zong, Tongxing Xia, Jianli Wang, and Haojie Liu. "Seismic inversion using complex spherical-wave reflection coefficient at different offsets and frequencies." GEOPHYSICS 87, no. 2 (January 10, 2022): R183—R192. http://dx.doi.org/10.1190/geo2020-0787.1.

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Compared with the plane-wave reflection coefficient, the spherical-wave reflection coefficient (SRC) can more accurately describe the reflected wavefield excited by a point source, especially in the case of low seismic frequency and short travel distance. However, unlike the widely used plane-wave amplitude-variation-with-offset/frequency (AVO/AVF) inversion, the practical application of spherical-wave AVO/AVF inversion in multilayer elastic media is still in the exploratory stage. One of the difficulties is how to fully use the amplitude and phase information of the complex-valued SRC and the spherical-wave response property of each frequency component to obtain the spherical-wave synthetic seismogram in multilayer elastic media. In view of this, we have developed a complex convolution model considering the amplitude and phase information of an SRC to obtain the complex synthetic seismogram of a certain frequency component. A simple harmonic superposition method is further developed. By superposing the complex synthetic seismograms of different frequency components, the synthetic seismogram of the full-frequency band can be obtained. In addition, a novel three-parameter SRC in terms of P- and S-wave moduli and density is derived. Based on the SRC and complex seismic traces with different offsets (or incidence angles) and frequency components, an inversion approach of complex spherical-wave amplitude and phase variation with offset and frequency is proposed. A noisy synthetic data example verifies the robustness of our complex spherical-wave inversion approach. Field data examples indicate that the P- and S-wave moduli estimated by the complex spherical-wave inversion approach can reasonably match the filtered well-logging data. Considering spherical waves rather than plane waves can improve the accuracy of seismic inversion results.

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10

Nowack, Robert. "Gaussian beam synthetic seismograms." Journal of the Acoustical Society of America 79, S1 (May 1986): S14. http://dx.doi.org/10.1121/1.2023080.

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Ma, Shu Qin, Martha Savage, and Jiashun Yu. "Modelling ground motion in the Hutt Valley, New Zealand." Bulletin of the New Zealand Society for Earthquake Engineering 40, no. 4 (December 31, 2007): 190–99. http://dx.doi.org/10.5459/bnzsee.40.4.190-199.

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The Hutt Valley is an alluvial basin that hosts the city of Lower Hutt, in the North Island, New Zealand. The basin is bounded by the Wellington Fault on its northwest side, and exhibits ground motion amplification factors up to about 15, measured by several seismic experiments using weak motion and portable seismic arrays during 1990-1991. Synthetic seismograms computed by using local 1D stratigraphic models under each station reproduce qualitatively the amplitudes and durations of the corresponding observed seismograms at most of the soft site stations of the arrays. Amplification factors estimated from spectral ratios of the synthetic seismograms are up to about 9. The authors present comparisons of amplification between synthetics and observations, allowing a “calibration” of the model so that it could be used to determine more realistic ground amplifications for earthquake scenarios.

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Qi, Chen, and Fred Hilterman. "Quantification of signal and noise in two-way transmitted wavefields to improve well ties in Cooper Basin, Australia." Interpretation 2, no. 2 (May 1, 2014): SD19—SD31. http://dx.doi.org/10.1190/int-2013-0129.1.

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Permian coal beds at 2400–2900 m depth in Cooper Basin, Australia have normal-incident reflection coefficient values as large as [Formula: see text]. If internal multiples are included in synthetic seismograms, excellent correlations exist between the synthetic seismogram and seismic, even when more than 50 coal beds are present. However, neither the synthetic seismogram nor the seismic tie the well-log lithologic boundaries because the incident wavefield that strikes a lithologic boundary and returns to the surface contains a signal wavelet followed by high-amplitude noise, which are interbed multiple reflections. Because the spectra of the signal and noise coda at a given two-way time normally do not overlap, time-varying Gaussian filters applied to the near-offset stack enhance the signal and suppress the noise coda. After filtering, the apparent time delay of reflections introduced by the coal beds is removed with variable time shifts (time compression), based on the estimated time-varying signal wavelets. The two-step process of low-pass filtering and compression yields seismic events that successfully tie the lithologic boundaries in the borehole, although with limited resolution. Our preliminary tests on a seismic line indicate that the horizon event associated with the base of a 500-m-thick coal sequence is more coherently imaged with our processing than with conventional processing.

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Chen, Xiaofei. "Seismogram synthesis for multi-layered media with irregular interfaces by global generalized reflection/transmission matrices method. II. Applications for 2D SH case." Bulletin of the Seismological Society of America 85, no. 4 (August 1, 1995): 1094–106. http://dx.doi.org/10.1785/bssa0850041094.

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Abstract As the second part of a series study attempting to present a new method of seismogram synthesis for the irregular multi-layered media problems, the present article is devoted to discussing the aspects of the implementation of our new formulation developed earlier in part I of this series study (Chen, 1990). In this article, we have verified the validity of the formulation by comparing our numerical results with the existing analytical solutions for the scattering problem of a semi-circular canyon, and have shown its applicability by computing the synthetic seismograms for several selected irregular multi-layered media cases. Finally, applying our algorithm to the Whittier-Narrows earthquake of 1987, we have successfully interpreted the observed records.

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Simmons, James L., and Milo M. Backus. "AVO modeling and the locally converted shear wave." GEOPHYSICS 59, no. 8 (August 1994): 1237–48. http://dx.doi.org/10.1190/1.1443681.

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The locally converted shear wave is often neglected in ray‐trace modeling when reproduction of the AVO response of potential hydrocarbon reservoirs is attempted. Primaries‐only ray‐trace modeling in which the Zoeppritz equations describe the reflection amplitudes is most common. The locally converted shear waves, however, often have a first‐order effect on the seismic response. This fact does not appear to be widely recognized, or else the implications are not well understood. Primaries‐only Zoeppritz modeling can be very misleading. Interference between the converted waves and the primary reflections from the base of the layers becomes increasingly important as layer thicknesses decrease. This interference often produces a seismogram that is very different from one produced under the primaries‐only Zoeppritz assumption. For primaries‐only modeling of thin layers, synthetic seismograms obtained by use of a linearized approximation to the Zoeppritz equations to describe the reflection coefficients are more accurate than those obtained by use of the exact Zoeppritz reflection coefficients. A real‐data example consisting of an assemblage of very thin layers has recently been discussed in the literature. Inferences as to the true earth properties based on the predicted amplitude variation with offset are in error because the primaries‐only assumption is invalid. For one of the models, primaries‐only modeling predicts an amplitude increase of approximately a factor of three from the near trace to the far trace. Reflectivity modeling predicts an amplitude decrease with offset. The O’Doherty‐Anstey effect suggests that transmission loss for primary reflections should not be included in normal‐incidence synthetic seismograms if the short‐period reverberations are not also included. The same principle holds for prestack modeling. Similarly, the Zoeppritz equations should not be used for synthetic seismograms without including the locally converted shear wave.

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Turgut, Altan, and Tokuo Yamamoto. "Synthetic seismograms for marine sediments and determination of porosity and permeability." GEOPHYSICS 53, no. 8 (August 1988): 1056–67. http://dx.doi.org/10.1190/1.1442542.

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We present numerical simulations of vertical seismic profiles (VSPs) of marine sediments. The theoretical seismograms, which are computed for vertically incident waves in flat layered poroelastic media, include the effects of dispersion and attenuation predicted by Biot theory. According to Biot theory, fast and slow compressional waves are excited and there is mode conversion at the interfaces. We include this effect in the calculation of reflection and transmission coefficients as an energy‐loss mechanism through the slow compressional waves. Finally, we examine the spectral ratio method for determining porosity and permeability from synthetic seismogram data. Analytical expressions for the velocity and specific attenuation are found based on the weak‐frame approximation. Once the frequency‐dependent velocity and specific attenuation are calculated, the porosity and permeability of marine sediments can be determined by using the proposed weak‐frame approximations. Spectral ratio calculations on synthetic examples show that Biot’s theory incorporated in the VSP method can be used to determine the porosity and permeability of marine sediments.

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Druzhinin, A., H. Pedersen, M. Campillo, and W. Kim. "Elastic Kirchhoff-Helmholtz Synthetic Seismograms." Pure and Applied Geophysics 151, no. 1 (January 1, 1998): 17–45. http://dx.doi.org/10.1007/s000240050103.

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Li, Lin, and Jinfeng Ma. "The influence of pore system change during CO2 storage on 4D seismic interpretation." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 74 (2019): 81. http://dx.doi.org/10.2516/ogst/2019047.

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A 4D seismic forward model constitutes the foundation of 4D seismic inversion. Here, in combination with the Gassmann equation, the Digby model is improved to calculate the S-wave velocity, and the resulting equation is verified using rock testing results. Then, considering the influences of changes in the pore pressure, CO2 saturation and porosity on the P- and S- wave velocities, rock testing results from a CO2 injection area in the Weyburn field are used to calculate the P- and S-wave velocities of the reservoir. These P- and S-wave velocities are found to overlap under different pressure conditions with or without considering porosity variations. Therefore, two-layer models and well models are developed to simulate synthetic seismograms; the models considering porosity variations may provide greater seismic responses and different Amplitude Versus Offset (AVO) trends in the synthetic seismogram profiles than those without considering porosity variations. Thus, porosity variations must be considered when establishing 4D seismic forward models.

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Chakraborty, Avijit, and David Okaya. "Frequency‐time decomposition of seismic data using wavelet‐based methods." GEOPHYSICS 60, no. 6 (November 1995): 1906–16. http://dx.doi.org/10.1190/1.1443922.

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Spectral analysis is an important signal processing tool for seismic data. The transformation of a seismogram into the frequency domain is the basis for a significant number of processing algorithms and interpretive methods. However, for seismograms whose frequency content vary with time, a simple 1-D (Fourier) frequency transformation is not sufficient. Improved spectral decomposition in frequency‐time (FT) space is provided by the sliding window (short time) Fourier transform, although this method suffers from the time‐ frequency resolution limitation. Recently developed transforms based on the new mathematical field of wavelet analysis bypass this resolution limitation and offer superior spectral decomposition. The continuous wavelet transform with its scale‐translation plane is conceptually best understood when contrasted to a short time Fourier transform. The discrete wavelet transform and matching pursuit algorithm are alternative wavelet transforms that map a seismogram into FT space. Decomposition into FT space of synthetic and calibrated explosive‐source seismic data suggest that the matching pursuit algorithm provides excellent spectral localization, and reflections, direct and surface waves, and artifact energy are clearly identifiable. Wavelet‐based transformations offer new opportunities for improved processing algorithms and spectral interpretation methods.

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Doser, Diane I., and Hiroo Kanamori. "Long-period surface waves of four western United States earthquakes recorded by the Pasadena strainmeter." Bulletin of the Seismological Society of America 77, no. 1 (February 1, 1987): 236–43. http://dx.doi.org/10.1785/bssa0770010236.

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Abstract Long-period surface waves recorded on the north-south Pasadena strainmeter are used to determine the seismic moments and fault parameters of the 19 May 1940 Imperial Valley, California, the 16 December 1954 Dixie Valley and Fairview Peak, Nevada, and the 18 August 1959 Hebgen Lake, Montana, earthquakes. Synthetic strain seismograms are matched with the observed strainmeter seismograms. Source parameters from the strainmeter modeling are more consistent with source parameters estimated from geodetic and geologic information than parameters estimated from short-period (<15 sec) body wave data. Long-period surface wave moment estimates agree well with geodetic estimates of moment, but are 1.5 to 5 times greater than moments obtained from modeling of teleseismic body waves or geologic information. The Imperial Valley earthquake is best modeled as consisting of 5 point sources along a fault 87.5 km in length with a strike, rake, and dip of 326°, 180°, and 90°. The moment for the earthquake was 4.8 × 1019 N-m. The synthetic seismogram that best models the Fairview Peak and Dixie Valley earthquakes assumes that the Fairview Peak earthquake was twice the size of the Dixie Valley event. Moments of 5.9 to 13 × 1019 and 3 to 6.5 × 1019 N-m are obtained for these events. A moment of 1.5 × 1020 N-m is obtained for the Hebgen Lake earthquake. Love waves of this earthquake are best modeled by a fault striking 102°, although surface faulting produced during the earthquake strikes 130°.

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Brysk, Henry, and Douglas W. McCowan. "Direct inversion of slant-stacked seismic data. Part I. Synthetic seismogram results." Bulletin of the Seismological Society of America 76, no. 3 (June 1, 1986): 815–35. http://dx.doi.org/10.1785/bssa0760030815.

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Abstract Bube and Burridge (1983) have investigated direct inverse methods in the time domain for solving the acoustic equation in one space dimension for the impedance profile. Since every slowness in a proper slant stack is a rescaled plane wave component, the technique can legitimately be applied to each trace individually. We have developed a robust estimation procedure that combines the (overdetermined) set of solutions in the τ − p domain to invert not just the impedance profile but the density and wave velocity separately. We have successfully applied the method to synthetic seismogram data for which neither the density, the wave velocity, nor the impedance are monotone functions of depth. Satisfactory results have been obtained after convolution of the model seismograms with a variety of source wavelets and after addition of random noise of amplitude comparable in level to the rms signal. We note that our method and results are for an acoustic equation model which may be inappropriate for physical models which generate significant shear waves from interface conversions.

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Gray, Samuel H., Chester A. Jacewitz, and Michael E. Epton. "Analytic synthetic seismograms for depth migration testing." GEOPHYSICS 56, no. 5 (May 1991): 697–700. http://dx.doi.org/10.1190/1.1443087.

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By using the fact that raypaths in a linear acoustic velocity field are circular arcs, we analytically generate a number of distinct nontrivial synthetic seismograms. The seismograms yield accurate traveltimes from reflection events, but they do not give reflection amplitudes. The seismograms are useful for testing seismic migration programs for both speed and accuracy, in settings where lateral velocity variations can be arbitrarily high and dipping reflectors arbitrarily steep. Two specific examples are presented as illustrations.

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Yuan, Yanhua O., and Frederik J. Simons. "Multiscale adjoint waveform-difference tomography using wavelets." GEOPHYSICS 79, no. 3 (May 1, 2014): WA79—WA95. http://dx.doi.org/10.1190/geo2013-0383.1.

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Full-waveform seismic inversions based on minimizing the distance between observed and predicted seismograms are, in principle, able to yield better-resolved earth models than those minimizing misfits derived from traveltimes alone. Adjoint-based methods provide an efficient way of calculating the gradient of the misfit function via a sequence of forward-modeling steps, which, using spectral-element codes, can be carried out in realistically complex media. Convergence and stability of full-waveform-difference adjoint schemes are greatly improved when data and synthetics are progressively presented to the algorithms in a constructive multiscale approximation using a (bi)orthogonal wavelet transform. Wavelets provide the nonredundant spectral decomposition that paves the way for the inversion to proceed successively from long-wavelength fitting to detailed exploration of the phases in the seismogram. The choice of wavelet class and type, the initial depth of the multiscale decomposition, and the minimization algorithms used at every level continue to play crucial roles in our procedure, but adequate choices can be made that test successfully on 2C elastic seismograms generated in toy models, as well as in the industry-standard 2D Marmousi model. Although for simplicity our inversion ignored surface waves by prior tapering and filtered removal, those also appeared to be very well matched in the final model.

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Thybo, Hans. "Wrap‐around removal from one‐dimensional synthetic seismograms." GEOPHYSICS 54, no. 7 (July 1989): 911–15. http://dx.doi.org/10.1190/1.1442720.

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One‐dimensional (1-D) synthetic seismograms are important tools in seismic exploration. They play an important role in the correlation of recorded seismograms with borehole logs and also permit the estimation of delay‐type attenuation in finely layered models. Existing computational methods for computing 1-D seismograms can be grouped according to whether the calculations are performed in the time domain or in the frequency domain.

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Krischer, Lion, Alexander R. Hutko, Martin van Driel, Simon Stähler, Manochehr Bahavar, Chad Trabant, and Tarje Nissen‐Meyer. "On‐Demand Custom Broadband Synthetic Seismograms." Seismological Research Letters 88, no. 4 (April 19, 2017): 1127–40. http://dx.doi.org/10.1785/0220160210.

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Loewenthal, Dan, and Paul L. Stoffa. "Synthetic acoustic seismograms by dereverberating sources." Journal of the Acoustical Society of America 90, no. 2 (August 1991): 1101–5. http://dx.doi.org/10.1121/1.402299.

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Thomson, C. J., and C. H. Chapman. "End-point contributions to synthetic seismograms." Geophysical Journal International 87, no. 1 (October 1986): 285–94. http://dx.doi.org/10.1111/j.1365-246x.1986.tb04558.x.

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LANGSTON, CHARLES A. "Wave Propagation Theory and Synthetic Seismograms." Reviews of Geophysics 29, S2 (January 1991): 662–70. http://dx.doi.org/10.1002/rog.1991.29.s2.662.

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Wu, Xinming, and Guillaume Caumon. "Simultaneous multiple well-seismic ties using flattened synthetic and real seismograms." GEOPHYSICS 82, no. 1 (January 1, 2017): IM13—IM20. http://dx.doi.org/10.1190/geo2016-0295.1.

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Well-seismic ties allow rock properties measured at well locations to be compared with seismic data and are therefore useful for seismic interpretation. Numerous methods have been proposed to compute well-seismic ties by correlating real seismograms with synthetic seismograms computed from velocity and density logs. However, most methods tie multiple wells to seismic data one by one; hence, they do not guarantee lateral consistency among multiple well ties. We therefore propose a method to simultaneously tie multiple wells to seismic data. In this method, we first flatten synthetic and corresponding real seismograms so that all seismic reflectors are horizontally aligned. By doing this, we turn multiple well-seismic tying into a 1D correlation problem. We then compute only vertically variant but laterally constant shifts to correlate these horizontally aligned (flattened) synthetic and real seismograms. This two-step correlation method maintains lateral consistency among multiple well ties by computing a laterally and vertically optimized correlation of all synthetic and real seismograms. We applied our method to a 3D real seismic image with multiple wells and obtained laterally consistent well-seismic ties.

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Mourhatch, Ramses, and Swaminathan Krishnan. "Simulation of Broadband Ground Motion by Superposing High-Frequency Empirical Green’s Function Synthetics on Low-Frequency Spectral-Element Synthetics." Geosciences 10, no. 9 (August 27, 2020): 339. http://dx.doi.org/10.3390/geosciences10090339.

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Seismic wave-propagation simulations are limited in their frequency content by two main factors: (1) the resolution of the seismic wave-speed structure of the region in which the seismic waves are propagated through; and (2) the extent of our understanding of the rupture process, mainly on the short length scales. For this reason, high-frequency content in the ground motion must be simulated through other means. Toward this end, we adopt a variant of the classical empirical Green’s function (EGF) approach of summing, with suitable time shift, recorded seismograms from small earthquakes in the past to generate high-frequency seismograms (0.5–5.0 Hz) for engineering applications. We superimpose these seismograms on low-frequency seismograms, computed from kinematic source models using the spectral element method, to produce broadband seismograms. The non-uniform time- shift scheme used in this work alleviates the over-estimation of high-frequency content of the ground motions observed. We validate the methodology by simulating broadband motions from the 1999 Hector Mine and the 2006 Parkfield earthquakes and comparing them against recorded seismograms.

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Hosseini, Kasra, and Karin Sigloch. "ObspyDMT: a Python toolbox for retrieving and processing large seismological data sets." Solid Earth 8, no. 5 (October 12, 2017): 1047–70. http://dx.doi.org/10.5194/se-8-1047-2017.

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Abstract. We present obspyDMT, a free, open-source software toolbox for the query, retrieval, processing and management of seismological data sets, including very large, heterogeneous and/or dynamically growing ones. ObspyDMT simplifies and speeds up user interaction with data centers, in more versatile ways than existing tools. The user is shielded from the complexities of interacting with different data centers and data exchange protocols and is provided with powerful diagnostic and plotting tools to check the retrieved data and metadata. While primarily a productivity tool for research seismologists and observatories, easy-to-use syntax and plotting functionality also make obspyDMT an effective teaching aid. Written in the Python programming language, it can be used as a stand-alone command-line tool (requiring no knowledge of Python) or can be integrated as a module with other Python codes. It facilitates data archiving, preprocessing, instrument correction and quality control – routine but nontrivial tasks that can consume much user time. We describe obspyDMT's functionality, design and technical implementation, accompanied by an overview of its use cases. As an example of a typical problem encountered in seismogram preprocessing, we show how to check for inconsistencies in response files of two example stations. We also demonstrate the fully automated request, remote computation and retrieval of synthetic seismograms from the Synthetics Engine (Syngine) web service of the Data Management Center (DMC) at the Incorporated Research Institutions for Seismology (IRIS).

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Sandmeier, K. J., and F. Wenzel. "Synthetic seismograms for a complex crustal model." Geophysical Research Letters 13, no. 1 (January 1986): 22–25. http://dx.doi.org/10.1029/gl013i001p00022.

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Sen, Mrinal K., and L. Neil Frazer. "Multifold phase space path integral synthetic seismograms." Geophysical Journal International 104, no. 3 (April 2, 2007): 479–87. http://dx.doi.org/10.1111/j.1365-246x.1991.tb05695.x.

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Bhattacharya, S. N. "Generation of synthetic seismograms with layer reduction." Geophysical Journal International 111, no. 1 (October 1992): 79–90. http://dx.doi.org/10.1111/j.1365-246x.1992.tb00556.x.

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34

Xu, Tong, and George A. McMechan. "Composite memory variables for viscoelastic synthetic seismograms." Geophysical Journal International 121, no. 2 (May 1995): 634–39. http://dx.doi.org/10.1111/j.1365-246x.1995.tb05738.x.

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Nowack, R. L. "Calculation of Synthetic Seismograms with Gaussian Beams." Pure and Applied Geophysics 160, no. 3 (March 2003): 487–507. http://dx.doi.org/10.1007/pl00012547.

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Hanyga, Andrzej, and Hans B. Helle. "Synthetic seismograms from generalized ray tracing 1." Geophysical Prospecting 43, no. 1 (January 1995): 51–75. http://dx.doi.org/10.1111/j.1365-2478.1995.tb00124.x.

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Savage, Martha Kane, and John G. Anderson. "A local-magnitude scale for the western Great Basin-eastern Sierra Nevada from synthetic Wood-Anderson seismograms." Bulletin of the Seismological Society of America 85, no. 4 (August 1, 1995): 1236–43. http://dx.doi.org/10.1785/bssa0850041236.

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Abstract We have computed synthetic Wood-Anderson seismograms for over 1100 arrivals at 10 three-component, broadband digital stations in the UNR western Great Basin-eastern Sierra Nevada network. These represent all the available records from local earthquakes over magnitude 3.5 between 1990 and June of 1993, plus selected events of smaller magnitude. There were 77 events ranging in magnitude from 2.2 to 5.9, including four events over magnitude 5. The distances considered ranged from 15 to 600 km, with the best-represented range being from 30 to 450 km. We invert these measurements to determine distance and station corrections appropriate for a local-magnitude scale, constrained by Richter's original definition that an earthquake of ML = 3 will cause a 1-mm zero to peak deflection of the Wood-Anderson seismogram at 100 km from the epicenter. The results between 30 and 450 km were essentially independent of choice of curve-fitting parameters. In the 30- to 500-km distance region, the smooth distance-correction curves were very similar to that determined by Richter (1958), which is still used for southern California earthquakes. We propose to use Richter's distance-correction curve in reporting amplitude magnitudes from our digital network.

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Hara, Tatsuhiko, and Robert J. Geller. "Anomalously large near-field Rayleight waves excited by the 1992 Landers, California, earthquake." Bulletin of the Seismological Society of America 84, no. 3 (June 1, 1994): 751–60. http://dx.doi.org/10.1785/bssa0840030751.

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Abstract The epicenter of the Landers, California, earthquake (28 June 1992; MW = 7.3) was located near the TERRAscope network of broadband seismic stations. The direct Rayleigh wave arrivals, R1, were clipped, and the first two later arrivals, R2 and R3, were contaminated by the waves from a large aftershock, but, as reported by Kanamori et al. (1992a), the amplitudes of R4 and later great circle Rayleigh wave arrivals (fundamental mode spheroidal free oscillations) are about 10 times larger than predicted by synthetic seismograms for a spherically symmetric earth model. We show that, for the moment tensor of the Landers event (predominantly vertical strike slip), the amplitudes of synthetics at the TERRAscope stations for a laterally heterogeneous, rotating, elliptical model are about 10 times greater than those for a spherically symmetric model. Because the anomaly ratio is sensitive to both the source model and the three-dimensional (3D) earth model, we do not attempt to reproduce the exact anomaly ratios recorded by the various stations. To explain the existence of near-field amplitude anomalies in general, we use the first-order Born approximation to find the perturbation to the synthetic seismogram resulting from lateral heterogeneity, ellipticity, and the earth's rotation. In a coordinate system with the source on the z axis a point-source strike-slip earthquake on a vertical fault plane in a spherically symmetric medium excites Rayleigh waves with azimuthal order ±2 only; these waves have a near-field vertical displacement of zero at the source; the displacement increases with the square of epicentral distance for any given azimuth. Coupling as a result of asphericity allows such a source to excite Rayleigh waves with azimuthal order zero, whose near-field amplitude is independent of epicentral distance, thereby generating large near-field amplitude anomalies. We conduct numerical experiments to study the influence of various parameters on near-field amplitude anomalies.

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Gochioco, Lawrence M. "Shallow VSP work in the U.S. Appalachian coal basin." GEOPHYSICS 63, no. 3 (May 1998): 795–99. http://dx.doi.org/10.1190/1.1444390.

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Most geophysical applications in North American coal exploration have centered around the conventional surface seismic reflection method to provide continuous subsurface coverage for evaluating both good and anomalous coal reserve areas (Ruskey, 1981; Dobecki and Bartel, 1982; Greaves, 1984; Lawton, 1985; Lyatsky and Lawton, 1988; Gochioco and Cotten, 1989; Lawton and Lyatsky, 1989; Gochioco and Kelly, 1990; Gochioco, 1991; Henson and Sexton, 1991). The surface seismic reflection method, however, has inherent resolution limitations because the seismic wavelet must propagate substantial distances through the weathered layer, resulting in rapid attenuation of the desired higher frequencies. Since the depths and thicknesses of coal seams are usually known before‐hand, it is imperative that the seismic reflection associated with the target coal seam is absolutely identified in the seismic section to avoid misinterpretations. However, it is common that checkshot data and sonic and density logs are not available to generate synthetic seismograms to assist in the interpretation of coal seismic data. To overcome some of these limitations, the vertical seismic profiling (VSP) technique was tested in a coal exploration program to provide additional information for correlation with surface seismic reflection [or common‐depth‐point (CDP)] data and a synthetic seismogram generated from density and sonic logs.

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Sarma, G. S., K. Mallick, and V. R. Gadhinglajkar. "Nonreflecting boundary condition in finite‐element formulation for an elastic wave equation." GEOPHYSICS 63, no. 3 (May 1998): 1006–16. http://dx.doi.org/10.1190/1.1444378.

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Numerical modeling of seismic wavefields using finite‐difference or finite‐element methods requires truncation of the model to finite computational domains. It is well known that the edges of such truncated models give boundary reflections on the synthetic seismograms. An essential step to successful numerical modeling is to eliminate these reflections. We present a simple scheme that eliminates such boundary reflections when computing synthetics. We also demonstrate the efficiency and robustness of our method on a variety of geological models.

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Bajc, J., Ž. Zaplotnik, M. Živčić, and M. Čarman. "Local magnitude scale in Slovenia." Advances in Geosciences 34 (April 30, 2013): 23–28. http://dx.doi.org/10.5194/adgeo-34-23-2013.

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Abstract. In the paper a calibration study of the local magnitude scale in Slovenia is presented. The Seismology and Geology Office of the Slovenian Environment Agency routinely reports the magnitudes MLV of the earthquakes recorded by the Slovenian seismic stations. The magnitudes are computed from the maximum vertical component of the ground velocity with the magnitude equation that was derived some thirty years ago by regression analysis of the magnitudes recorded by a Wood-Anderson seismograph in Trieste and a short period seismograph in Ljubljana. In the study the present single magnitude MLV equation is replaced by a general form of the Richter local magnitude MWA equation. The attenuation function and station-component corrections that compensate the local effects near seismic stations are determined from the synthetic Wood-Anderson seismograms of a large data set by iterative least-square method. The data set used consists of approximately 18 000 earthquakes during a period of 14 yr, each digitally recorded on up to 29 stations. The derived magnitude equation is used to make the final comparison between the new MWA magnitudes and the routinely calculated MLV magnitudes. The results show good overall accordance between both magnitude equations. The main advantage of the introduction of station-component corrections is the reduced uncertainty of the local magnitude that is assigned to a certain earthquake.

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42

Mendoza, Carlos, and Stephen H. Hartzell. "Inversion for slip distribution using teleseismic P waveforms: North Palm Springs, Borah Peak, and Michoacan earthquakes." Bulletin of the Seismological Society of America 78, no. 3 (June 1, 1988): 1092–111. http://dx.doi.org/10.1785/bssa0780031092.

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Abstract We have inverted the teleseismic P waveforms recorded by stations of the Global Digital Seismograph Network for the 8 July 1986 North Palm Springs, California, the 28 October 1983 Borah Peak, Idaho, and the 19 September 1985 Michoacan, Mexico, earthquakes to recover the distribution of slip on each of the faults using a point-by-point inversion method with smoothing and positivity constraints. In the inversion procedure, a fault plane with fixed strike and dip is placed in the region of the earthquake hypocenter and divided into a large number of subfaults. Rupture is assumed to propagate at a constant velocity away from the hypocenter, and synthetic ground motions for pure strike-slip and dip-slip dislocations are calculated at the teleseismic stations for each subfault. The observed seismograms are then inverted to obtain the distribution of strike-slip and dip-slip displacement for the earthquake. Results of the inversion indicate that the Global Digital Seismograph Network data are useful for deriving fault dislocation models for moderate to large events. However, a wide range of frequencies, which includes periods shorter than those within the passband of the long-period Global Digital Seismograph Network instruments, is necessary to infer the distribution of slip on the earthquake fault. Although the long-period waveforms define the size (dimensions and seismic moment) of the earthquake, data at shorter periods provide additional constraints on the variation of slip on the fault. Dislocation models obtained for all three earthquakes are consistent with a heterogeneous rupture process where failure is controlled largely by the size and location of high-strength asperity regions.

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Guennou, C. "Synthetic Seismograms in Transversely Isotropic Plane Layered Media." Revue de l'Institut Français du Pétrole 53, no. 5 (September 1998): 643–54. http://dx.doi.org/10.2516/ogst:1998058.

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Cansi, Yves, and Nicole Bethoux. "T waves with Long Inland Paths: Synthetic seismograms." Journal of Geophysical Research: Solid Earth 90, B7 (June 10, 1985): 5459–65. http://dx.doi.org/10.1029/jb090ib07p05459.

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45

Frazer, L. N. "Synthetic seismograms using multifold path integrals - I. Theory." Geophysical Journal International 88, no. 3 (March 1, 1987): 621–46. http://dx.doi.org/10.1111/j.1365-246x.1987.tb01649.x.

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Sen, M. K., and L. N. Frazer. "Synthetic seismograms using multifold path integrals - II. Computations." Geophysical Journal International 88, no. 3 (March 1, 1987): 647–71. http://dx.doi.org/10.1111/j.1365-246x.1987.tb01650.x.

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47

Cummins, Phil R. "DSM complete synthetic seismograms: SH, spherically symmetric, case." Deleted DOIs 21, no. 7 (1994): 533–36. http://dx.doi.org/10.1029/94gl00013a.

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Cummins, Phil R., Robert J. Geller, Tomohiko Hatori, and Nozomu Takeuchi. "DSM complete synthetic seismograms: SH, spherically symmetric, case." Geophysical Research Letters 21, no. 7 (April 1, 1994): 533–36. http://dx.doi.org/10.1029/gl021i007p00533.

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49

Javaherian, Abdolrahim. "Grid dispersion in generating finite-differences synthetic seismograms." Acta Seismologica Sinica 7, no. 3 (August 1994): 397–407. http://dx.doi.org/10.1007/bf02650677.

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Dey, A., and A. Gisolf. "Wide-angle linear forward modelling of synthetic seismograms." Geophysical Prospecting 55, no. 5 (September 2007): 707–18. http://dx.doi.org/10.1111/j.1365-2478.2007.00586.x.

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Journal articles on the topic 'Synthethic seismograms'

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