共查询到20条相似文献，搜索用时 250 毫秒
1.
2.
The development of seismic wave study in China in the past four years is reviewed. The discussion is divided into several aspects, including seismic wave propagation in laterally homogeneous media, laterally heterogeneous media, anisotropic and porous media, surface wave and seismic wave inversion, and seismic wave study in prospecting and logging problems. Important projects in the current studies on seismic wave is suggested as the development of high efficient numerical methods, and applying them to the studies of excitation and propagation of seismic waves in complex media and strong ground motion, which will form a foundation for refined earthquake hazard analysis and prediction. 相似文献
3.
应用混合变量弹性动力学方程和线性常微分方程组的矩阵指数解法，将层状介质中广泛应用的弹性波传播矩阵解法推广至横向非均匀介质，给出了一种可计算复杂地质体中弹性波传播的广义传播矩阵数值解法。该方法可模拟任意震源及所产生的各种体波、面波，数值结果表明具有很高的计算精度。 相似文献
4.
5.
Vlastislav Červený I. A. Molotkov Ivan Pšenčík Reviewer J. Vaněk 《Studia Geophysica et Geodaetica》1982,26(4):342-351
Summary The space-time ray method can be applied to the evaluation and continuation (extrapolation) of the complete seismic wave field in laterally inhomogeneous media with curved interfaces. The wave field propagates along certain space-time curves, called space-time rays. Their space projections correspond to standard rays. Examples of possible applications of the space-time ray method, where the standard ray method fails, are as follows: a) The propagation of seismic waves in slightly dissipative media, b) The computation of seismic wave fields generated by seismic sources with direction-dependent source-time variations. c) Downward continuation of the seismic wave field (actual seismograms) measured at the Earth's surface. 相似文献
6.
The Numerical Modeling of 3-D Elastic Wave Equation Using a High-Order,Staggered-Grid, Finite Difference Scheme 总被引：1，自引：0，他引：1
XiaFan DongLiangguo MaZaitian 《应用地球物理》2004,1(1):38-41
This article provides the application of the high-order, staggered-grid, finite-difference scheme to model elastic wave propagation in 3-D isotropic media. Here, we use second-order, temporal-and high-order spatial finite-difference formulations with a staggered grid for discretization of the 3-D elastic wave equations of motion. The set of absorbing boundary conditions based on paraxial approximations of 3-D elastic wave equations are applied to the numerical boundaries. The trial resuits for the salt model show that the numerical dispersion is decreased to a minimum extent, the accuracy high and diffracted waves abundant. It also shows that this method can be used for modeling wave propagation in complex media with the lateral variation of velocity. 相似文献
7.
Parabolic Equation Techniques for Seismic Waves 总被引：1，自引：0，他引：1
W. Jerzak M. D. Collins R. B. Evans J. F. Lingevitch W. L. Siegmann 《Pure and Applied Geophysics》2002,159(7-8):1681-1689
— Parabolic equation techniques for solving seismic wave propagation problems are discussed. These techniques provide an excellent combination of accuracy and efficiency for problems involving laterally varying media. Due to recent improvements, the parabolic equation method is applicable to problems involving wide propagation angles, large variations in the properties of the medium, and all types of waves. 相似文献
8.
9.
Based on the modified Biot＇s theory of two-phase porous media, a study was presented on seismic reflection and transmission coefficients at an air-water interface of saturated porous soil media. The major differences between air-saturated soils and water-saturated soils were theoretically discussed, and the theoretical formulas of reflection and transmission coefficients at an air-water interface were derived. The characteristics of propagation and attenuation of elastic waves in air-saturated soils were given and the relations among the frequency, the angle of incidence and the reflection, transmission coefficients were analyzed by using numerical methods. Numerical results show that the propagation characteristic of the wave in air-saturated soils is great different from that in water-saturated soils. The frequency and the angle of incidence can have great influences on the reflection and transmission coefficients at interface. Some new cognition about the wave propagation is obtained and the study suggests that we may carefully pay attention to the influence of air on the dynamic analysis of seismic wave. 相似文献
10.
11.
传统的Kirchhoff传播算子结构简洁,适用于描述横向均匀介质中波的传播.Ray-Kirchhoff传播算子较为精确地描述了波在非均匀介质中传播的运动学特征,其理论上的先天不足依赖于介质的复杂性.本文通过Born序列逼近波在非均匀介质中传播的大角度波分量,提出一种Born-Kirchhoff传播算子,将传统Kirchhoff传播算子的适用范围扩展至非均匀介质,同时描述波的运动学和动力学特征,其精度取决于Born序列逼近的阶数.利用Born序列频散方程,可以精确分析各阶Born-Kirchhoff传播算子对波长、传播角和非均质性的尺度依赖特征,其中,一阶Born-Kirchhoff传播算子的精度高于传统的相屏传播算子.波数域的Born-Kirchhoff传播算子对于高波数波是奇异的,导致波数域数值计算发散,但其空间域版本是非奇异的,无条件数值稳定,可通过Kirchhoff求和数值实施.本文给出各阶Born-Kirchhoff传播算子及其频散方程,可用于不同程度非均匀介质中的波传播模拟,复杂构造地震成像和速度估计.本文利用零阶和一阶Born-Kirchhoff传播算子计算简单二维模型的合成地震图,并与边界元法进行了比较. 相似文献
12.
13.
提出了一种在时间和空间上完全局域化的波场分解和传播算法─dreamlet偏移方法.Dreamlet是一种脉冲-小波束形式的波场分解原子,它利用多维局部分解变换,把时空域波场映射到局部时间-频率-空间-波数相空间,并用局部相空间的传播算子(dreamlet算子)沿深度延拓.本文利用多维局部余弦变换实现dreamlet算法,分解后的波场系数和传播算子不仅有很好的稀疏性,且均为实数,也即波的传播和成像过程完全在实数域实现.文中推导了局部余弦基dreamlet波场分解和传播算子理论公式并将其应用于叠前深度偏移.在dreamlet相空间波的传播过程为稀疏矩阵相乘,而且延拓后的地表数据波场的有效时间长度随深度的增加不断减小,从而可以减少需要传播的波场系数.二维SEG/EAGE盐丘和SIGSBEE模型算例验证了理论推导的正确性,成像结果显示该方法在横向速度变化剧烈情况下有很好的精度. 相似文献
14.
Wave-induced flow is observed as the dominated factor for P wave propagation at seismic frequencies. This mechanism has a mesoscopic scale nature. The inhomogeneous unsaturated patches are regarded larger than the pore size, but smaller than the wavelength. Surface wave, e.g., Rayleigh wave, which propagates along the free surface, generated by the interfering of body waves is also affected by the mesoscopic loss mechanisms. Recent studies have reported that the effect of the wave-induced flow in wave propagation shows a relaxation behavior. Viscoelastic equivalent relaxation function associated with the wave mode can describe the kinetic nature of the attenuation. In this paper, the equivalent viscoelastic relaxation functions are extended to take into account the free surface for the Rayleigh surface wave propagation in patchy saturated poroelastic media. Numerical results for the frequency-dependent velocity and attenuation and the time-dependent dynamical responses for the equivalent Rayleigh surface wave propagation along an interface between vacuum and patchy saturated porous media are reported in the low-frequency range (0.1–1,000 Hz). The results show that the dispersion and attenuation and kinetic characteristics of the mesoscopic loss effect for the surface wave can be effectively represented in the equivalent viscoelastic media. The simulation of surface wave propagation within mesoscopic patches requires solving Biot’s differential equations in very small grid spaces, involving the conversion of the fast P wave energy diffusion into the Biot slow wave. This procedure requires a very large amount of computer consumption. An efficient equivalent approach for this patchy saturated poroelastic media shows a more convenient way to solve the single phase viscoelastic differential equations. 相似文献
15.
地震各向异性研究进展 总被引：28，自引：21，他引：28
简要介绍了各向异性介质中地震波传播理论的最新研究进展，总结了地震各向异性在地球动力学，地震灾害监测以及资源探查等方面的应用研究新进展。目前，主要通过数值模拟和物理模拟来研究地球内部典型各向异性介质中波的传播规律；利用横波分裂，Pn波的方位变化，面波成像方法研究地球内部的结构和物质交换，应力场的变化以及地震的孕育和发生过程。在资源探查中，地震各向异性理论主要用于解决测线不闭合，中长排列动校，时深转换以及裂缝分布等问题。 相似文献
16.
17.
基于岩石物里学中临界孔隙度模型,建立一种简洁的均匀弹性流体饱和孔隙介质模型,进行地震波传播研究.首先定义了构建目标模型的基本力学模型:介绍了全孔隙度区间内基本力学模型和目标孔隙介质的含义,其中基本力学模型除了完全弹性固体模型S和完全弹性流体模型F还包括临界孔隙模型C.然后通过等效力学模型推出了目标力学模型介质本构关系的组分表达形式.文中分别通过直接求取弹性参数的表达形式和运用应力应变关系两种方法得到介质模型的本构关系,进而得到该模型波动方程的组分表达形式.最后对这种介质模型进行了地震波传播的数值模拟,结合模拟结果分析孔隙对地震波传播的影响. 相似文献
18.
The earth media friction attenuates the energy of seismic wave. Obviously, that earth medium is treated as viscoelasticity is more appropriate than as elasticity. Seismic wave in visco-elastic media contains abundant lithology information of the medium. The investiga-tions of the solutions of visco-elastic wave equations, velocities of seismic wave propagating and the at-tenuation of seismic wave in the visco-elastic media are very important for geophysical prospecting tech-nology. Under a sma… 相似文献
19.
20.
The study of seismic attenuation property is a major subject in seismology. Seismic waves recorded by seismic stations （seismographs） contain source effect, seismic wave propagation effect, site response of seismic stations and instrumental response. The path effect of seismic wave propagation, site response of seismic stations and instrumental response must be taken out in the study of source property with seismic data. The path effect of seismic wave propagation （seismic attenuation） involves an important influential factor, the anelastic attenuation of medium, which is measured with quality factor Q, apart from geometric attenuation with the distance. As a basic physical parameter of the Earth medium, Q value is essential for quantitative study of earthquakes and source property （e.g. determination of source parameters）, which is widely used in earthquake source physics and engineering seismology. 相似文献