Interpretation of surface wave spectra in laterally inhomogeneous media     

Peter Malischewsky 《Geophysical Journal International》1989,99(2):305-306

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Propagation of Extremely Low Frequency Waves Through the Ionosphere     

Singh  Ashok K.  Narayan  D.  Singh  R. P. 《Earth, Moon, and Planets》2002,91(3):161-179

The propagation features of extremely low frequency electromagnetic waves through the multicomponent ionospheric plasma are studied. It is shown that at relatively lower frequencies refractive index for right hand mode is higher than the left-hand mode, which is reversed at higher frequencies. The thermal temperature of plasma particle causes decrease in phase and group velocities of both right and left-hand modes. The crossover frequencies for different plasma models are computed and variation with ion concentration and thermal velocity is studied. Explicit expression for group velocity and travel time has been derived and studied numerically. Finally, we have presented simulation of the ion whistler spectrograms for Hydrogen, Helium and Oxygen ions present in the ionospheric plasma. The results are compared with the experimentally detected hydrogen and helium ion whistlers. The importance of the present study in the exploration of ionospheric plasma is illustrated.  相似文献   

地形作用下有限振幅Rossby波的稳定性分析     

周定文  彭晓林  罗德海 《成都信息工程学院学报》1990,(Z1)

本文用微分方程定性理论方法分析了地形对有限振幅Rossby波的稳定性影响。结果表明:地形北坡有利于波动出现不稳定,南坡使波动稳定;西坡使导式波动不稳定但使曳式波动稳定,东坡使导式波动稳定但使曳式波动不稳定。  相似文献   

Wave propagation within random packings of spheres     

K. Walton 《Geophysical Journal International》1988,92(1):89-97

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Source signature and elastic waves in a half‐space under a momentary shear line impulse     

Moche Ziv 《国际地质力学数值与分析法杂志》2003,27(3):233-258

The transient deformation of an elastic half‐space under a line‐concentrated impulsive vector shear load applied momentarily is disclosed in this paper. While in an earlier work, the author gave an analytical–numerical method for the solution to this transient boundary‐value problem, here, the resultant response of the half‐space is presented and interpreted. In particular, a probe is set up for the kinematics of the source signature and wave fronts, both explicitly revealed in the strained half‐space by the solution method. The source signature is the imprint of the spatiotemporal configuration of the excitation source in the resultant response. Fourteen wave fronts exist behind the precursor shear wave S: four concentric cylindrical, eight plane, and two relativistic cylindrical initiated at propagating centres that are located on the stationary boundaries of the solution domain. A snapshot of the stressed half‐space reveals that none of the 14 wave fronts fully extend laterally. Instead, each is enclosed within point bounds. These wave arresting points and the two propagating centres of the relativistic waves constitute the source signature. The obtained 14 wave fronts are further combined into 11 disparate wave fronts that are grouped into four categories: an axis of symmetry wave—so named here by reason of being a wave front that is contiguous to the axis of symmetry, three body waves, five surface waves and two inhibitor waves—so named here by reason that beyond them the material motion dies out. Of the three body waves, the first is an unloading shear wave, the second is a diffracted wave and the third is a reflected longitudinal two‐branch wave. Of the two inhibitor waves, the first is a two‐joint relativistic wave, while the second is a two‐branch wave. The wave system, however, is not the same for all the dependent variables; a wave front that appears in the behaviour of one dependent variable may not exist in the behaviour of another. It is evident from this work that Saint–Venant's principle for wave propagation problems cannot be formulated. Therefore, the above results are valid for the particular proposed model for the momentary line‐concentrated shear load. The formulation of the source signature, the wave system, and their role in the half‐space transient deformation are presented here. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Precursory arrivals to PP     

Mamoru Kato  Kazuro Hirahara 《Geophysical Journal International》1991,106(3):551-557

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The edge wave superposition method (2-D scalar problem)     

K. D. Klem-Musatov  A. M. Aizenberg 《Geophysical Journal International》1989,99(2):351-367

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中国强震迁移与现代地壳波浪运动     

胡连英 《地球科学与环境学报》1988,(3)

本文论述了中国强震迁移与现代地壳波浪运动间的关系,指出了中国强震时空分布上的波浪性、方向性及丛集性特征,并将中国强震运动划分为天平式运动、单波系波浪运动、双波系波浪运动、多波系波浪运动等类型,进而对强震机制进行了探讨,指出强震波带和强震丛集区仍是今后强震活动的主要场所。  相似文献   

Factors affecting wave magnitude and period during the earthquakes of September, 1985     

Enrique del Valle Toledo 《Geotechnical and Geological Engineering》1989,7(1):29-35

Summary The geology and structure of the Mexico Basin are discussed and hypotheses developed to explain the magnification of wave amplitudes during the 1985 earthquake.  相似文献   

Multiple scattering of seismic waves, variable gas saturation and ZODs: theoretical considerations and an observational methodology     

I. Lerche 《Geophysical Journal International》1986,86(2):241-261

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