Refining higher modes of Rayleigh waves using seismoelectric signals excited by a weight‐drop source: study from numerical simulation aspect

In surface-wave analysis, S-wave velocity estimations can be improved by the use of higher modes of the surface waves. The vertical component of P-SV waves is commonly used to estimate multimode Rayleigh waves, although Rayleigh waves are also included in horizontal components of P-SV waves. To demonstrate the advantages of using the horizontal components of multimode Rayleigh waves, we investigated the characteristics of the horizontal and vertical components of Rayleigh waves. We conducted numerical modeling and field data analyses rather than a theoretical study for both components of Rayleigh waves. As a result of a simulation study, we found that the estimated higher modes have larger relative amplitudes in the vertical and horizontal components as the source depth increases. In particular, higher-order modes were observed in the horizontal component data for an explosive source located at a greater depth. Similar phenomena were observed in the field data acquired by using a dynamite source at 15-m depth. Sensitivity analyses of dispersion curves to S-wave velocity changes revealed that dispersion curves additionally estimated from the horizontal components can potentially improve S-wave velocity estimations. These results revealed that when the explosive source was buried at a greater depth, the horizontal components can complement Rayleigh waves estimated from the vertical components. Therefore, the combined use of the horizontal component data with the vertical component data would contribute to improving S-wave velocity estimations, especially in the case of buried explosive source signal.

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Approximation to Cutoffs of Higher Modes of Rayleigh Waves for a Layered Earth Model

Pure and Applied Geophysics ◽

10.1007/s00024-008-0443-4 ◽

2009 ◽

Vol 166 (3) ◽

pp. 339-351 ◽

Cited By ~ 14

Author(s):

Yixian Xu ◽

Jianghai Xia ◽

Richard D. Miller

Keyword(s):

Rayleigh Waves ◽

Earth Model ◽

Higher Modes ◽

Layered Earth

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THE SEISMIC WAVE SYSTEM FROM A SURFACE IMPACT

Geophysics ◽

10.1190/1.1440614 ◽

1976 ◽

Vol 41 (2) ◽

pp. 243-265 ◽

Cited By ~ 10

Author(s):

Harold M. Mooney

Keyword(s):

Rayleigh Waves ◽

Pulse Length ◽

Wave System ◽

P Waves ◽

S Waves ◽

Impact Surface ◽

Seismic Waveforms ◽

Detector Distance ◽

Weight Drop ◽

Drop Impacts

A theory presented in an earlier paper (Mooney, 1974) has been used to compute seismic waveforms produced by a surface impact. Surface detectors are assumed which measure displacement, velocity, acceleration, or strain in either vertical or horizontal components. A physically plausible source waveform is considered which is unidirectional, symmetrical about a peak, and with zero slopes at beginning and end. Theoretical waveforms are presented for models simulating projectile, hammer, and weight‐drop impacts onto granite, concrete, and soil. The waveforms show small but clear P arrivals, large Rayleigh pulses, and no recognizable S waves. P waves are larger on the horizontal sensors, Rayleigh on the vertical. The waveforms differ markedly from one detector type to another and show little resemblance to the source waveform. Distinctive pulse length and amplitude pulse paramaters are selected. Pulse lenths are shown to be relatively insensitive to detector distance, hence conversion factors can be obtained from which to infer source pulse length. These factors were applied to accelerometer waveforms obtained experimentally from steel pellet impacts onto granite, yielding a source pulse length of 30 μsec. This value was used to compute theoretical waveforms which show satisfactory agreement with the experimental waveforms. The measured amplitude parameters are shown to depend upon detector distance r and source pulse length T and amplitude H as [Formula: see text]where n = 1, 1/2 for P and Rayleigh waves, respectively; p = 0, 1/2 for P and Rayleigh waves; and m = 0,1,2,1 for detectors which measure displacement, particle velocity, acceleration, and horizontal strain. An increase in Poisson’s ratio v for the medium produces increased time separation between P and Rayleigh arrivals, and increase in P pulse length and amplitude, no changes in Rayleigh pulse length, and a decrease in Rayleigh amplitude as [Formula: see text].

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Resolution oi Upper Mantle Structure Using Higher Modes of Rayleigh Waves (*).

Annals of Geophysics ◽

10.4401/ag-4834 ◽

2010 ◽

Vol 30 (3-4) ◽

Author(s):

L. KNOPOFF ◽

G. P. PANZA

Keyword(s):

Upper Mantle ◽

Rayleigh Waves ◽

Mantle Structure ◽

Higher Modes ◽

Upper Mantle Structure

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MATHEMATICAL MODELING OF NON-STATIONARY ELASTIC WAVES STRESSES UNDER A CONCENTRATED VERTICAL EXPOSURE IN THE FORM OF DELTA FUNCTIONS ON THE SURFACE OF THE HALF-PLANE (LAMB PROBLEM)

International Journal for Computational Civil and Structural Engineering ◽

10.22337/2587-9618-2019-15-2-111-124 ◽

2019 ◽

Vol 15 (2) ◽

pp. 111-124

Author(s):

Vyacheslav Musayev

Keyword(s):

Numerical Simulation ◽

Finite Element Method ◽

Finite Element ◽

Free Surface ◽

Boundary Conditions ◽

Half Plane ◽

Rayleigh Waves ◽

The Finite Element Method ◽

Initial And Boundary Conditions ◽

Element Method

The problem of numerical simulation of longitudinal, transverse and surface waves on the free surface of an elastic half-plane is considered. The change of the elastic contour stress on the free surface of the halfplane is given. To solve the two-dimensional unsteady dynamic problem of the mathematical theory of elasticity with initial and boundary conditions, we use the finite element method in displacements. Using the finite element method in displacements, a linear problem with initial and boundary conditions resulted in a linear Cauchy problem. Some information on the numerical simulation of elastic stress waves in an elastic half-plane under concentrated wave action in the form of a Delta function is given. The amplitude of the surface Rayleigh waves is significantly greater than the amplitudes of longitudinal, transverse and other waves with concentrated vertical action in the form of a triangular pulse on the surface of the elastic half-plane. After the surface Rayleigh waves there is a dynamic process in the form of standing waves.

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Higher modes of continental Rayleigh waves

Bulletin of the Seismological Society of America ◽

10.1785/bssa0470030187 ◽

1957 ◽

Vol 47 (3) ◽

pp. 187-204 ◽

Cited By ~ 2

Author(s):

Jack Oliver ◽

Maurice Ewing

Keyword(s):

Wave Equation ◽

Particle Motion ◽

High Frequency ◽

Rayleigh Waves ◽

Velocity Curve ◽

Theoretical Studies ◽

Higher Modes ◽

Short Period ◽

First Time ◽

Rayleigh Mode

ABSTRACT A long dispersive train of waves corresponding to higher modes of the Rayleigh-wave equation (including Sezawa's M2 wave) for the continental crust-mantle system is positively identified, apparently for the first time. Observed particle motion is elliptical and retrograde, in agreement with theory. Although several theoretical studies have been published in which progressive elliptical particle motion was found, all of these involved values of the elastic constants unsuitable for the present problem. The beginnings of the short-period branches of the higher modes can account for the high-frequency longitudinal and vertical components of the continental surface-wave phase Lg. The large amplitudes and the peculiar appearance of Rg appear to depend on the broad flat minimum of the group velocity curve of the lowest or Rayleigh mode.

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