Sound waves and shear waves in saturated unconsolidated sediments

Sound waves travel very easily underground, often for many thousands of kilometres. These are usually referred to as a kind of seismic wave and are most often triggered by earthquakes, which result from a sudden slip of tectonic plates, down to about 700 kilometres below the Earth’s surface. ‘Seismic waves’ describes the four types of seismic wave generated by earthquakes: P-waves (primary waves), S-waves (shear waves), Love waves (usually the most powerful and destructive of seismic waves), and Rayleigh waves, which are created when P and S waves reach the Earth’s surface together, combining to form undulating ground rolls. Free vibrations and star waves are also described.

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The interaction of electrons with ultrasonic shear waves in copper

Canadian Journal of Physics ◽

10.1139/p70-004 ◽

1970 ◽

Vol 48 (1) ◽

pp. 13-20 ◽

Cited By ~ 1

Author(s):

A. M. Simpson ◽

M. H. Jericho

Keyword(s):

Fermi Surface ◽

Magnetic Field Dependence ◽

Surface Deformation ◽

Shear Waves ◽

Theoretical Description ◽

Sound Waves ◽

Conduction Electrons ◽

Strong Polarization ◽

Ultrasonic Shear ◽

The Magnetic Field

Measurements of the electronic component of the acoustic attenuation of shear waves travelling in the [110] direction in copper are reported. The magnetic field dependence of the attenuation has also been investigated in fields up to 50 kG. The data have been compared with theory on the basis of a simple examination of the Fermi surface of copper. The results show strong polarization dependence of the attenuation and suggest that when [math], a detailed theoretical description will require consideration of electromagnetic as well as Fermi surface deformation interactions of sound waves with the conduction electrons.

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Crustal structure and surface-wave dispersion*

Bulletin of the Seismological Society of America ◽

10.1785/bssa0400040271 ◽

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.

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