scholarly journals Crustal structure and surface-wave dispersion*

1950 ◽  
Vol 40 (4) ◽  
pp. 271-280
Author(s):  
Maurice Ewing ◽  
Frank Press
Keyword(s):  
Rayleigh Waves ◽  
Shear Waves ◽  
Seismic Refraction ◽  
Thick Layer ◽  
Water Layer ◽  
Wave Dispersion ◽  
Unconsolidated Sediments ◽  
Sediment Layer ◽  
Surface Wave Dispersion ◽  
Significant Difference

Summary The observed dispersion of Rayleigh waves across the Atlantic and Pacific oceans can be accounted for by considering the propagation of such waves through a system consisting of water and unconsolidated sediments overlying a thick layer of ultrabasic rock. This contrasts with all former treatments, which have considered the effect of the water layer to be negligible. The depth of the water-sediment layer and the speed of shear waves in the underlying ultrabasic layer are obtained for several paths across the Atlantic and Pacific oceans. The results for the Atlantic are in good agreement with the data obtained in a recent seismic refraction measurement made 120 miles northwest of Bermuda, and offer strong evidence that the result of this single refraction measurement will be found to be typical of the entire ocean. No significant difference in the nature of the suboceanic basement of the Atlantic and Pacific has been found, since the velocity of shear waves in the upper-most 50 to 100 km. was calculated to be 4.45 km/sec. for both oceans. Previously reported differences in Atlantic and Pacific velocities for Rayleigh waves of some selected period are now believed to be due primarily to differences in the depth of water plus sediment in the two oceans.

scholarly journals Crustal structure and surface-wave dispersion. part II Solomon Islands earthquake of July 29, 1950*

1952 ◽  
Vol 42 (4) ◽  
pp. 315-325
Author(s):  
Maurice Ewing ◽  
Frank Press
Keyword(s):  
North Atlantic ◽  
Rayleigh Waves ◽  
Solomon Islands ◽  
Seismic Refraction ◽  
Shear Velocity ◽  
Wave Dispersion ◽  
Surface Wave Dispersion ◽  
Basement Structure ◽  
The Pacific ◽  
Dispersion Part

Abstract Rayleigh waves from the Solomon Islands earthquake of July 29, 1950, recorded at Honolulu, Berkeley, Tucson, and Palisades are analyzed. Both the direct waves and those propagated through the Antipodes were observed for all stations except Honolulu. Application of a correction for land travel results in a dispersion curve for the oceanic portion of the path. It is found that the observed dispersion could be accounted for by propagation through a layer of water 5.57 km. thick overlying simatic rocks having shear velocity 4.56 km/sec. and density 3.0 gm/cc. Basement structure in the Pacific, Indian, South Atlantic, and North Atlantic oceans is ideptical within the limits of accuracy of the method. The sinusoidal nature and duration of the coda is explained by the effect of the oceans on the propagation of Rayleigh waves. The results are compatible with seismic refraction measurements in the Atlantic and Pacific oceans.

DISPERSION IN SEISMIC SURFACE WAVES

Geophysics ◽  
1951 ◽  
Vol 16 (1) ◽  
pp. 63-80 ◽  
Author(s):  
Milton B. Dobrin
Keyword(s):  
Surface Waves ◽  
Water Waves ◽  
Seismic Refraction ◽  
Wave Theory ◽  
Wave Dispersion ◽  
Surface Zone ◽  
Surface Wave Dispersion ◽  
Near Surface ◽  
Arrival Times ◽  
Ground Roll

A non‐mathematical summary is presented of the published theories and observations on dispersion, i.e., variation of velocity with frequency, in surface waves from earthquakes and in waterborne waves from shallow‐water explosions. Two further instances are cited in which dispersion theory has been used in analyzing seismic data. In the seismic refraction survey of Bikini Atoll, information on the first 400 feet of sediments below the lagoon bottom could not be obtained from ground wave first arrival times because shot‐detector distances were too great. Dispersion in the water waves, however, gave data on speed variations in the bottom sediments which made possible inferences on the recent geological history of the atoll. Recent systematic observations on ground roll from explosions in shot holes have shown dispersion in the surface waves which is similar in many ways to that observed in Rayleigh waves from distant earthquakes. Classical wave theory attributes Rayleigh wave dispersion to the modification of the waves by a surface layer. In the case of earthquakes, this layer is the earth’s crust. In the case of waves from shot‐holes, it is the low‐speed weathered zone. A comparison of observed ground roll dispersion with theory shows qualitative agreement, but it brings out discrepancies attributable to the fact that neither the theory for liquids nor for conventional solids applies exactly to unconsolidated near‐surface rocks. Additional experimental and theoretical study of this type of surface wave dispersion may provide useful information on the properties of the surface zone and add to our knowledge of the mechanism by which ground roll is generated in seismic shooting.

Surface-wave dispersion computations

1970 ◽  
Vol 60 (2) ◽  
pp. 321-344 ◽  
Author(s):  
Fred Schwab ◽  
Leon Knopoff
Keyword(s):  
Half Space ◽  
Rayleigh Waves ◽  
Wave Dispersion ◽  
Reduction Technique ◽  
Surface Wave Dispersion ◽  
Single Precision ◽  
Homogeneous Half Space ◽  
Full Control ◽  
Significant Figures ◽  
Rayleigh Wave Dispersion

abstract Fundamental-mode Love- and Rayleigh-wave dispersion computations for multilayered, perfectly-elastic media were studied. The speed of these computations was improved, and the accuracy brought under full control. With sixteen decimal digits employed in these computations, fifteen significant-figure accuracy was found possible with Love waves and twelve to thirteen figure accuracy with Rayleigh waves. In order to ensure that the computed dispersion is correct to a specified accuracy, say σ significant figures, (σ + 1)/4 wavelengths of layered structure must be retained above a homogeneous half-space. To this accuracy, the homogeneous half-space is a sufficient model of the true layering it replaces. Using this result, it was possible to refine the usual layer-reduction technique so as to ensure retention of the specified accuracy while employing reduction. With this reduction technique in effect, and with σ specified below single-precision accuracy, the program can be run entirely in single precision; the specified accuracy is maintained without overflow or loss-of-precision problems being encountered during calculations.

Shear-wave velocity measurement of soils using Rayleigh waves

1992 ◽  
Vol 29 (4) ◽  
pp. 558-568 ◽  
Author(s):  
K. O. Addo ◽  
P. K. Robertson
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Rayleigh Waves ◽  
Ground Surface ◽  
Wave Dispersion ◽  
Velocity Variation ◽  
Surface Wave Dispersion ◽  
Waveform Data ◽  
Cone Penetration Tests

A modified version of the spectral analysis of surface waves (SASW) equipment and analysis procedure has been developed to determine in situ shear-wave velocity variation with depth from the ground surface. A microcomputer has been programmed to acquire waveform data and perform the relevant spectral analyses that were previously done by signal analyzers. Experimental dispersion for Rayleigh waves is now obtainable at a site and inverted with a fast algorithm for dispersion computation. Matching experimental and theoretical dispersion curves has been automated in an optimization routine that does not require intermittent operator intervention or experience in dispersion computation. Shear-wave velocity profiles measured by this procedure are compared with results from independent seismic cone penetration tests for selected sites in western Canada. Key words : surface wave, dispersion, inversion, optimization, shear-wave velocity.

scholarly journals A fast, convenient program for computation of surface-wave dispersion curves in multilayered media

1961 ◽  
Vol 51 (4) ◽  
pp. 495-502
Author(s):  
Frank Press ◽  
David Harkrider ◽  
C. A. Seafeldt
Keyword(s):  
Surface Wave ◽  
Rayleigh Waves ◽  
High Speed ◽  
Wave Dispersion ◽  
Dispersion Curves ◽  
Mail Order ◽  
Mantle Structure ◽  
Wave Analysis ◽  
Multilayered Media ◽  
Surface Wave Dispersion

Abstract Surface wave analysis has become an important tool for exploration of crustal and mantle structure. The need exists for fast, convenient digital computer programs for computing theoretical dispersion curves and displacements for Rayleigh waves and Love waves. One such program for an IBM 7090 computer is described and made available to the scientific community. Among the conveniences are mail-order service, high speed, and choice of many options.

scholarly journals Perturbational and nonperturbational inversion of Rayleigh-wave velocities

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. F15-F28 ◽  
Author(s):  
Matthew M. Haney ◽  
Victor C. Tsai
Keyword(s):  
Rayleigh Wave ◽  
Group Velocity ◽  
Rayleigh Waves ◽  
Water Layer ◽  
Wave Dispersion ◽  
Velocity Measurements ◽  
Root Finding ◽  
Depth Sensitivity ◽  
Starting Model ◽  
And Inversion

The inversion of Rayleigh-wave dispersion curves is a classic geophysical inverse problem. We have developed a set of MATLAB codes that performs forward modeling and inversion of Rayleigh-wave phase or group velocity measurements. We describe two different methods of inversion: a perturbational method based on finite elements and a nonperturbational method based on the recently developed Dix-type relation for Rayleigh waves. In practice, the nonperturbational method can be used to provide a good starting model that can be iteratively improved with the perturbational method. Although the perturbational method is well-known, we solve the forward problem using an eigenvalue/eigenvector solver instead of the conventional approach of root finding. Features of the codes include the ability to handle any mix of phase or group velocity measurements, combinations of modes of any order, the presence of a surface water layer, computation of partial derivatives due to changes in material properties and layer boundaries, and the implementation of an automatic grid of layers that is optimally suited for the depth sensitivity of Rayleigh waves.

scholarly journals Potential Use of Time-Lapse Surface Seismics for Monitoring Thawing of the Terrestrial Arctic

2020 ◽  
Vol 10 (5) ◽  
pp. 1875
Author(s):  
Helene Meling Stemland ◽  
Tor Arne Johansen ◽  
Bent Ole Ruud
Keyword(s):  
Surface Wave ◽  
Seismic Data ◽  
Rock Physics ◽  
Wave Dispersion ◽  
Time Lapse ◽  
Unconsolidated Sediments ◽  
Frozen Ground ◽  
Surface Wave Dispersion ◽  
Near Surface ◽  
Surface Temperatures

The terrestrial Arctic is warming rapidly, causing changes in the degree of freezing of the upper sediments, which the mechanical properties of unconsolidated sediments strongly depend upon. This study investigates the potential of using time-lapse surface seismics to monitor thawing of currently (partly) frozen ground utilizing synthetic and real seismic data. First, we construct a simple geological model having an initial temperature of −5 °C, and infer constant surface temperatures of −5 °C, +1 °C, +5 °C, and +10 °C for four years to this model. The geological models inferred by the various thermal regimes are converted to seismic models using rock physics modeling and subsequently seismic modeling based on wavenumber integration. Real seismic data reflecting altered surface temperatures were acquired by repeated experiments in the Norwegian Arctic during early autumn to mid-winter. Comparison of the surface wave characteristics of both synthetic and real seismic data reveals time-lapse effects that are related to thawing caused by varying surface temperatures. In particular, the surface wave dispersion is sensitive to the degree of freezing in unconsolidated sediments. This demonstrates the potential of using surface seismics for Arctic climate monitoring, but inversion of dispersion curves and knowledge of the local near-surface geology is important for such studies to be conclusive.

scholarly journals Computation of surface wave dispersion for multilayered anisotropic media

1962 ◽  
Vol 52 (2) ◽  
pp. 321-332 ◽  
Author(s):  
David G. Harkrider ◽  
Don L. Anderson
Keyword(s):  
Surface Wave ◽  
Rayleigh Wave ◽  
Rayleigh Waves ◽  
Love Wave ◽  
Transversely Isotropic ◽  
Wave Dispersion ◽  
Surface Wave Dispersion ◽  
Independent Evidence ◽  
Anisotropic Layers ◽  
Love Wave Dispersion

ABSTRACT With the program described in this paper it is now possible to compute surface wave dispersion in a solid heterogeneous halfspace containing up to 200 anisotropic layers. Certain discrepancies in surface wave observations, such as disagreement between Love and Rayleigh wave data and other independent evidence, suggest that anisotropy may be important in some seismological problems. In order to study the effect of anisotropy on surface wave dispersion a program was written for an IBM 7090 computer which will compute dispersion curves and displacements for Rayleigh waves in a layered halfspace in which each layer is transversely isotropic. A simple redefinition of parameters makes it possible to use existing programs to compute Love wave dispersion.

scholarly journals Crustal structure and surface-wave dispersion, Part III: Theoretical dispersion curves for suboceanic Rayleigh waves*

1953 ◽  
Vol 43 (2) ◽  
pp. 137-144
Author(s):  
W. S. Jardetzky ◽  
Frank Press
Keyword(s):  
Surface Wave ◽  
Crustal Structure ◽  
Rayleigh Waves ◽  
Wave Dispersion ◽  
Dispersion Curves ◽  
Surface Wave Dispersion ◽  
Different Types ◽  
Oceanic Basement ◽  
Rayleigh Wave Dispersion ◽  
Dispersion Part

Abstract Theoretical Rayleigh wave dispersion curves for three different types of sub-oceanic basement layering are presented. Previous conclusions concerning the dispersion of Rayleigh waves across ocean basins are re-examined in the light of the new data.

A summary of observed seismic surface wave dispersion

1962 ◽  
Vol 52 (1) ◽  
pp. 81-86
Author(s):  
Jack Oliver
Keyword(s):  
Surface Wave ◽  
Present State ◽  
Rayleigh Waves ◽  
Wave Dispersion ◽  
Surface Wave Dispersion ◽  
Phase And Group Velocities ◽  
Group Velocities

Abstract Two sets of curves relating phase and group velocities of Love and Rayleigh waves to periods summarize our present state of knowledge on seismic surface wave dispersion. Periods range from about one second to one hour, and velocities from about one kilometer per second to about eight kilometers per second.

Sign in / Sign up

Export Citation Format

Share Document