An equivalent fluid approximation for a low shear speed ocean bottom

1992 ◽  
Vol 91 (6) ◽  
pp. 3248-3256 ◽  
Author(s):  
C. T. Tindle ◽  
Z. Y. Zhang
Keyword(s):  
Ocean Bottom ◽  
Fluid Approximation ◽  
Shear Speed ◽  
Low Shear

Seismo-acoustic propagation near thin and low-shear speed ocean bottom sediments

2011 ◽  
Vol 130 (4) ◽  
pp. 2529-2529
Author(s):  
Jon M. Collis ◽  
Adam M. Metzler ◽  
Paden Reitz ◽  
Rezwanur Rahman
Keyword(s):  
Bottom Sediments ◽  
Acoustic Propagation ◽  
Ocean Bottom ◽  
Shear Speed ◽  
Low Shear

Seismo-acoustic propagation near thin and low-shear speed ocean bottom sediments

2012 ◽  
Vol 132 (3) ◽  
pp. 1973-1973
Author(s):  
Jon M. Collis ◽  
Adam M. Metzler ◽  
William L. Siegmann
Keyword(s):  
Bottom Sediments ◽  
Acoustic Propagation ◽  
Ocean Bottom ◽  
Shear Speed ◽  
Low Shear

scholarly journals Parabolic Equation Modeling of Scholte Waves and Other Effects Along Sloping Fluid-Solid Interfaces

2021 ◽  
pp. 2050025
Author(s):  
Michael D. Collins ◽  
Adith Ramamurti
Keyword(s):  
Parabolic Equation ◽  
Fluid Layer ◽  
Solid Material ◽  
Single Scattering ◽  
Equation Modeling ◽  
Wide Range ◽  
Scholte Waves ◽  
Scholte Wave ◽  
Shear Speed ◽  
Low Shear

Several methods for handling sloping fluid–solid interfaces with the elastic parabolic equation are tested. A single-scattering approach that is modified for the fluid–solid case is accurate for some problems but breaks down when the contrast across the interface is sufficiently large and when there is a Scholte wave. An approximate condition for conserving energy breaks down when a Scholte wave propagates along a sloping interface but otherwise performs well for a large class of problems involving gradual slopes, a wide range of sediment parameters, and ice cover. An approach based on treating part of the fluid layer as a solid with low shear speed is developed and found to handle Scholte waves and a wide range of sediment parameters accurately, but this approach needs further development. The variable rotated parabolic equation is not effective for problems involving frequent or continuous changes in slope, but it provides a high level of accuracy for most of the test cases, which have regions of constant slope. Approaches based on a coordinate mapping and on using a film of solid material with low shear speed on the rises of the stair steps that approximate a sloping interface are also tested and found to produce accurate results for some cases.

Converted shear waves as seen by ocean bottom seismometers and surface buoys

1977 ◽  
Vol 67 (5) ◽  
pp. 1291-1302 ◽  
Author(s):  
Brian T. R. Lewis ◽  
James McClain
Keyword(s):  
Shear Waves ◽  
Shear Velocity ◽  
Ocean Bottom ◽  
Sediment Layer ◽  
S Waves ◽  
High Attenuation ◽  
Ocean Bottom Seismometers ◽  
Sedimentary Layer ◽  
Low Shear

abstract It is found that ocean bottom seismometers (O.B.S.) deployed in sedimented areas produce markedly different seismograms from surface hydrophones. These differences are found to be due to ringing on the O.B.S. records produced by converted shear waves trapped in the sediment layer. These shear waves do not propagate into the water and hence the hydrophone record is much “cleaner” than the O.B.S. record. It is also shown that the presence of refracted shear waves like P-S-P and P-S-S may be related to the presence of a sedimentary layer in some areas. It is suggested that the disappearance of refracted S waves in some areas without sediment is related to high attenuation and/or very low shear velocities caused by cracks and inhomogeneities in the crust. Under sedimented areas the cracks may be sufficiently filled so as to substantially reduce the attenuation and/or increase the bulk shear velocity.

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