共查询到20条相似文献，搜索用时 937 毫秒
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Abdolrahim JAVAHERIAN 《地震学报(英文版)》1994,7(1):23-31
Ｔｈｅｏｐｔｉｍｕｍｓｏｕｒｃｅ－ｔｉｍｅｆｕｎｃｔｉｏｎｆｏｒｇｅｎｅｒａｔｉｎｇｆｉｎｉｔｅ－ｄｉｆｆｅｒｅｎｃｅｓｙｎｔｈｅｔｉｃｓｅｉｓｍｏｇｒａｍｓＡｂｄｏｌｒａｈｉｍＪＡＶＡＨＥＲＩＡＮ（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ｔｈｅ... 相似文献
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Synthetic seismograms generated by solving the seismic wave equation using numerical methods are being widely used in seismology. For fully three-dimensional seismic structure models, the generation of these synthetic seismograms may require large amount of computing resources. Conventional high-performance computer clusters may not provide a cost-effective solution to this type of applications. The newly emerging cloud-computing platform provides an alternative solution. In this paper, we describe our implementation of a synthetic seismogram generator based on the reciprocity principle using the Windows Azure cloud application framework. Our preliminary experiment shows that our cloud-based synthetic seismogram generator provides a cost-effective and numerically efficient approach for computing synthetic seismograms based on the reciprocity principle. 相似文献
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E. J. DOUZE 《Geophysical Prospecting》1979,27(3):564-575
Synthetic seismograms are usually computed for reflections from vertical incidence of P waves for a horizontally layered medium. In actual practice the angle of incidence departs from the vertical, as receivers are usually located at some distance from the source. At angles other than the vertical, the conversion of P- to S-wave energy and changes in the reflection coefficient affect the shape of the synthetic seismograms. The effect of non-vertical incidence on synthetic seismograms is examined in this paper. Seismograms at non-vertical incidence have been computed using the plane-wave approach of Haskell (1953) for a layered medium. The use of plane waves is an approximation to the actual case of spherical wavefronts from a surface source. Using plane-wave theory, the expected wave forms as a function of angle of incidence were computed numerically for several simple models. The results indicate that the synthetic seismograms do not change significantly for angles of incidence between o and 25 degrees. For larger angles the changes in the wave forms may be severe. The effect is more pronounced for high-velocity layers than for low-velocity layers. 相似文献
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井中震源在逆VSP、随钻地震和采矿地球物理研究中都有广泛应用.满足"小井孔"(井孔半径远小于特征波长)及"远场"(炮检距大于特征波长)假设时,井中震源的远场波场存在解析解.为了检验解析解在不同情况下的适用性,本文使用最速下降积分计算了不满足上述假设时井中震源远场波场的合成地震记录,即半解析解.模型试验表明,解析解只能在同时满足"小井孔"和"远场"假设时使用;当这两个假设条件不满足时,解析解的振幅和波形相对于半解析解会有明显的偏差.随着假设不满足程度的增加,偏差会逐渐增加,并会逐渐影响走时的准确拾取;这种条件下,采用半解析解才能获得准确的井中震源波场. 相似文献
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D. PATELLA 《Geophysical Prospecting》1980,28(5):744-749
The Hankel transform theorem can be applied to the inversion of gravity data for the buried sphere, the horizontal cylinder, and the vertical rod. This new approach leads to exact solutions of the transforms for the assumed bodies. A comparison with the classical procedure by Fourier transform reveals that for the sphere and the vertical rod, the Hankel transform is preferable. 相似文献
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正演模拟是叠前弹性波反演的基础.采用慢度法计算层状介质的叠前地震记录,分别对频率和慢度进行积分变换得到时-空域的地震道集,并对在慢度积分过程中产生的计算噪音提出了解决方案.为得到高精度合成地震记录,需将地层细分,但地层层数很多时,计算量较大;而对地层粗分虽然会大大加快运算速度,但合成记录会丢失很多信息,文中给出了地层的划分原则.该方法能够计算出包括转换波和多次反射在内的全地震响应.但在提高合成记录精度的同时,也导致计算量增大、计算效率降低,因此,本文对基于慢度法全波场模拟进行了并行算法设计,采用计算域分割、工作池并行技术,建立了慢度法全波场正演模拟的并行算法,使得弹性波正演问题求解更加高效,为充分利用叠前地震资料进行叠前反演提供了研究基础. 相似文献
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Elisa Zuccolo Tony Gibbs Carlo G. Lai Joan L. Latchman Walter Salazar Luigi Di Sarno Anthony Farrell Lloyd Lynch Addison Workman 《Bulletin of Earthquake Engineering》2016,14(9):2579-2605
A feasibility study of an earthquake early warning (EEW) system was conducted for the Eastern Caribbean region using scenario earthquakes, corresponding to the maximum credible earthquakes and to the earthquakes associated with a return period of 475 years. Broadband synthetic seismograms were produced at selected critical facilities, where there is potential interest in the installation of an EEW system. The expected damage was derived from the synthetic seismograms and compared with the lead-time determined for both a regional and on-site EEW configuration. Next, the Virtual Seismologist EEW algorithm, as included in SeisComP3, was tested. Additional broadband synthetic seismograms were produced for the stations in the Eastern Caribbean seismic networks in order to simulate the real time behaviour of the seismic networks during the occurrence of the synthetic earthquakes and to assess the predictive capacity of the selected ground motion prediction equation. Expected peak ground parameters and lead-times at the critical facilities constitute the major outcome of the study. 相似文献
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The need for synthetic seismograms arises in several acoustic well-logging contexts. We propose a numerical algorithm for computing the seismograms, characterized by a very reduced computational cost. Unlike previous contributions appearing in the technical literature, the proposed algorithm is based on a non-uniform sampling step and on linear interpolation for computing the integrals involved in the synthesis. 相似文献
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Libo Han Zhongliang Wu Yutong Li Changsheng Jiang 《Pure and Applied Geophysics》2014,171(3-5):425-437
For the identification and analysis of ‘repeating earthquakes,’ there are two empirical concepts. The first is the assumption that the cross-correlation coefficient of the filtered seismograms of closely spaced ‘repeaters’ depends exponentially on the inter-event separation distance. The second is the convention that in processing regional seismograms, a 0.5–5.0-Hz band pass filter is used. In this article, using a simple layered structure model, we investigated the cross-correlation coefficient of the filtered synthetic seismograms of two closely located events, that is, a ‘doublet.’ We investigated the relation between the cross-correlation coefficient and the inter-event separation distance. Simulation shows that in the 0.5–5.0-Hz frequency band, even if for simple synthetic seismograms without considering lateral heterogeneity or scattering, the exponential dependence is only a first order approximation concept. To check the frequency dependence of the cross-correlation coefficient, we analyzed a group of seismograms of a ‘multiplet’ in Xiuyan, Liaoning, northeast China, recorded by the Regional Seismographic Network of Liaoning Province. The cross-correlation coefficients were observed to be relatively stable against frequency for the 0.5–5.0-Hz frequency band. 相似文献
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传统的人工边界是在声波或弹性波分解为内行和外行分量的基础上设计的.对于较复杂的介质模型（如粘弹介质、弹塑介质、塑性介质模型等）,地震波不能简单地分解为各自满足其运动方程的纵波、横波等成分,且地震波在传播过程中还有衰减现象,因此传统的人工边界已不能有效地用于非弹性的较复杂介质的波场模拟.本文提出了一种适合于更一般的地震模型的波场计算的透射边界条件,并以粘弹介质的一个较简单的二维几何模型为例,通过有限元数值求解这种透射边界和刚性边界下粘弹波的激发和传播,得到地面合成地震记录,证明了这种透射边界用于较复杂介质波场计算是可行的. 相似文献
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合成地震图的广义反射透射系数矩阵方法 总被引：3，自引：1，他引：3
简述了在均匀层状介质中，合成地震图的广义反射透射系数矩阵方法，并通过与有人的计算结果对比，检验了经过修改调试后的合成地震图的计算程序。计算与对比表明，经修改调试后的程序对于各种因素，包括震源类型、震源深度、震中、频率和慢度都有较好的普适性，适用于实际的地震波形研究。 相似文献
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MONIKA BREITZKE 《Geophysical Prospecting》1992,40(1):31-70
In spite of a geometrical rotation into radial and transverse parts, two- or three-component in-seam seismic data used for underground fault detection often suffer from the problem of overmoding ‘noise’. Special recompression filters are required to remove this multimode dispersion so that conventional reflection seismic data processing methods, e.g. CMP stacking techniques, can be applied afterwards. A normal-mode superposition approach is used to design such multimode recompression filters. Based on the determination of the Green's function in the far-field, the normal-mode superposition approach is usually used for the computation of synthetic single- and multi-mode (transmission) seismograms for vertically layered media. From the filter theory's point of view these Green's functions can be considered as dispersion filters which are convolved with a source wavelet to produce the synthetic seismograms. Thus, the design of multimode recompression filters can be reduced to a determination of the inverse of the Green's function. Two methods are introduced to derive these inverse filters. The first operates in the frequency domain and is based on the amplitude and phase spectrum of the Green's function. The second starts with the Green's function in the time domain and calculates two-sided recursive filters. To test the performance of the normal-mode superposition approach for in-seam seismic problems, it is first compared and applied to synthetic finite-difference seismograms of the Love-type which include a complete solution of the wave equation. It becomes obvious that in the case of one and two superposing normal modes, the synthetic Love seam-wave seismograms based on the normal-mode superposition approach agree exactly with the finite-difference data if the travel distance exceeds two dominant wavelengths. Similarly, the application of the one- and two-mode recompression filters to the finite-difference data results in an almost perfect reconstruction of the source wavelet already two dominant wavelengths away from the source. Subsequently, based on the dispersion analysis of an in-seam seismic transmission survey, the normal-mode superposition approach is used both to compute one- and multi-mode synthetic seismograms and to apply one- and multimode recompression filters to the field data. The comparison of the one- and two-mode synthetic seismograms with the in-seam seismic transmission data reveals that arrival times, duration and shape of the wavegroups and their relative excitation strengths could well be modelled by the normal-mode superposition approach. The one-mode recompressions of the transmission seismograms result in non-dispersive wavelets whose temporal resolution and signal-to-noise ratio could clearly be improved. The simultaneous two-mode recompressions of the underground transmission data show that, probably due to band-limitation, the dispersion characteristics of the single modes could not be evaluated sufficiently accurately from the field data in the high-frequency range. Additional techniques which overcome the problem of band-limitation by modelling all of the enclosed single-mode dispersion characteristics up to the Nyquist frequency will be mandatory for future multimode applications. 相似文献
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Teleseismic receiver function using stacking and smoothing of multi seismic-records at a single station 
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下载免费PDF全文 Receiver functions (RFs) obtained using teleseismic wave records at a seismic station and synthetic seismograms indicate that RF with a single teleseismic wave record is related to the selection of record section and to the calculating parameters of the RF. The scatter noise contained in the seismogram also affects the quality of RF. A new method for calculating receiver function, stacking and smoothing multi-seismic records in a single station, is presented in this paper. The RF results using some records and some synthetic seismograms with different noises indicate prominent mantle discontinuity and thus prove that the method is effective and satisfied. 相似文献
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V. G. Krishna 《Journal of Seismology》2018,22(6):1395-1408
We present an approach based on controlled source seismology (CSS) methods, especially developed for processing and modeling of the local earthquake seismograms. Record sections of the local earthquake seismograms generated for multiple source depths illuminate the upper crustal velocity structure in the region. Extensive travel times and synthetic seismograms modeling of the observed record sections reveal the P and S velocity structure in the region. The strength of this approach essentially lies with the possibility of validating the upper crustal velocity models inferred in various subregions of the seismogenic region. A redundant and significantly large number of virtual source local earthquake seismogram sections, gathered for multiple source depths and varying source mechanisms in each of the subregions, validate the same set of P and S velocity models in that region. Further, those models are found to generate the synthetic seismograms consistent with the observed sections. The proposed approach effectively utilizes a reliable dataset from a great volume of well-located local earthquake recordings of a state-of-the-art digital seismograph network. Such a dataset of local earthquake seismograms in the Koyna-Warna active earthquake zone is used here to demonstrate this approach and obtained subregion-specific models of upper crustal P and S velocity structure in the epicentral region. The results indicate that the technique presented here is efficient for processing and modeling the local earthquake seismograms and deriving upper crustal velocity models in the seismogenic regions. 相似文献
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With the use of complete synthetic seismograms for the SH component of motion we have constructed theoretical isoseismals. We have assumed a double-couple point source as determined from first arrivals of P waves. Lateral heterogeneities around the source were also considered. In fact, the crustal part of the model used to compute synthetic seismograms to the west of the Bradano foretrough was significantly different from the one used to synthesize seismograms to the east of the foretrough. Even with such a simple approach, the comparison between theoretical and experimental data is surprisingly good, indicating that the isoseismals' elongation, parallel to the Apennines, depends mainly upon the fault orientation, while the effect of local structures introduces relatively small perturbations in the radiation pattern.Publication n. 198 Istituto di Geodesia e Geofisica-Trieste. 相似文献
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B. M. GURBUZ 《Geophysical Prospecting》1982,30(4):432-443
An analytical relationship for the autocorrelation function of an upsweep with high-frequency attenuation is used in the construction of synthetic seismograms. Field experiments were conducted in two areas to investigate the attenuation of upsweep where the near-surface materials were different. The results showed that the attenuation of high frequencies occurs at the source point depending on the near-surface lithology. The attenuation effect is usually neglected in the construction of the input wavelet of synthetic seismograms for Vibroseis data. In this study, the high-frequency attenuation of upsweep was considered in the construction of the input wavelet for the synthetic seismogram in an area where the Vibroseis technique was used. The synthetic seismogram generated in this manner had a better correlation with the Vibroseis section than that of corresponding synthetics using minimum-phase and the unattenuated autocorrelation wavelet of the upsweep. 相似文献
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A. T. DE HOOP 《Geophysical Prospecting》1988,36(5):465-477
Large horizontal offset and large vertical offset approximations in the modified Cagniard method for computing synthetic seismograms in a horizontally layered model of the earth are derived. They apply to each of the generalized-ray constituents into which the seismic wave motion is decomposed. For the results applying to large horizontal offset, which are known in the seismological literature, a simplified derivation is given. The results for large vertical offset, which are of particular interest to vertical seismic profiling, are new. The use of the large-offset approximations, both horizontal and vertical, leads to a considerable reduction in computation time for synthetic seismograms compared with the full three-dimensional version of the modified Cagniard method. 相似文献
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Realistic Modeling of Seismic Wave Ground Motion in Beijing City 总被引：5，自引：0，他引：5
— Algorithms for the calculation of synthetic seismograms in laterally heterogeneous anelastic media have been applied to model the ground motion in Beijing City. The synthetic signals are compared with the few available seismic recordings (1998, Zhangbei earthquake) and with the distribution of observed macroseismic intensity (1976, Tangshan earthquake). The synthetic three-component seismograms have been computed for the Xiji area and Beijing City. The numerical results show that the thick Tertiary and Quaternary sediments are responsible for the severe amplification of the seismic ground motion. Such a result is well correlated with the abnormally high macroseismic intensity zone in the Xiji area associated with the 1976 Tangshan earthquake as well as with the ground motion recorded in Beijing city in the wake of the 1998 Zhangbei earthquake. 相似文献