Journal ArticleDOI
Shallow water sediment properties derived from high‐frequency shear and interface waves
TLDR
In this paper, bottom-mounted sources and receivers were used to make measurements of shear and compressional wave propagation in shallow water sediments of the continental shelf, usually where boreholes and high-resolution reflection profiles give substantial supporting geologic information about the subsurface.Abstract:
Low-frequency sound propagation in shallow water environments is not restricted to the water column but also involves the subbottom. Thus, as well as being important for geophysical description of the seabed, subbottom velocity/attenuation structure is essential input for predictive propagation models. To estimate this structure, bottom-mounted sources and receivers were used to make measurements of shear and compressional wave propagation in shallow water sediments of the continental shelf, usually where boreholes and high-resolution reflection profiles give substantial supporting geologic information about the subsurface. This colocation provides an opportunity to compare seismically determined estimates of physical properties of the seabed with the “ground truth” properties. Measurements were made in 1986 with source/detector offsets up to 200 m producing shear wave velocity versus depth profiles of the upper 30–50 m of the seabed (and P wave profiles to lesser depths). Measurements in 1988 were made with smaller source devices designed to emphasize higher frequencies and recorded by an array of 30 sensors spaced at 1-m intervals to improve spatial sampling and resolution of shallow structure. These investigations with shear waves have shown that significant lateral and vertical variations in the physical properties of the shallow seabed are common and are principally created by erosional and depositional processes associated with glacial cycles and sea level oscillations during the Quaternary. When the seabed structure is relatively uniform over the length of the profiles, the shear wave fields are well ordered, and the matching of the data with full waveform synthetics has been successful, producing velocity/attenuation models consistent with the subsurface lithology indicated by coring results. Both body waves and interface waves have been modeled for velocity/attenuation as a function of depth with the aid of synthetic seismograms and other analytical techniques. Some results give strong evidence of anisotropy and lateral heterogeneity in shear velocity of the upper 5–10 m of sediments and of extremely high velocity gradients in the topmost 1–2 m, possibly exceeding 30 s−1.read more
Citations
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Journal ArticleDOI
Assessment of tsunami hazard to the U.S. East Coast using relationships between submarine landslides and earthquakes
TL;DR: In this paper, the authors proposed to estimate the size and recurrence interval of submarine landslides from the size of earthquakes in the near vicinity of the said landslides, and found that the calculated distance and failure areas from the slope stability analysis is similar or slightly smaller than the maximum triggering distances and failure area in subaerial observations.
Journal ArticleDOI
1.5D inversion of lateral variation of Scholte-wave dispersion
TL;DR: In this paper, Scholte waves are recorded in a common receiver gather generated by an air gun towed behind a ship away from a single stationary ocean-bottom seismometer, and a 2D shear-wave velocity section is generated.
Journal ArticleDOI
Fidelity of ocean bottom seismic observations
F.K. Duennebier,George H. Sutton +1 more
TL;DR: In this article, the authors suggest that the only reliable way of obtaining high fidelity particle motion data from the ocean floor is to bury the sensors below the bottom in a package with density close to that of the sediment.
Journal ArticleDOI
Sounds in the Ocean at 1-100 Hz
TL;DR: The increasing availability of long-term records of ocean sound will provide new opportunities for a deeper understanding of natural and anthropogenic sound sources and potential interactions between them.
Journal ArticleDOI
Scholte-wave tomography for shallow-water marine sediments
TL;DR: In this article, the 3D in situ shear-wave velocities of shallow-water marine sediments were determined by extending the method of surface wave tomography to Scholte-wave records acquired in shallow waters.
References
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Journal ArticleDOI
The existence of Stoneley waves as a loss mechanism in plane wave reflection problems
TL;DR: Hawker et al. as mentioned in this paper showed that the angles at which the reflection loss peaks occur are precisely those angles for which the horizontal component of phase velocity in the fluid equals the Stoneley wave phase velocity.
Journal ArticleDOI
Estimating SV‐wave stacking velocities for transversely isotropic solids
TL;DR: In this paper, the authors used isotropic methods to estimate the shear wave stacking velocities in transversely-isotropic media with vertical symmetry axes, where the anisotropic Snell's law approximates the a weakly-anisotropic SINR and the wavefront is smooth enough near the vertical axis to fit with an ellipse.
OtherDOI
Atlantic Margin Coring Project 1976: preliminary report on shipboard and some laboratory geotechnical data
Book ChapterDOI
Model Computations for Low-Velocity Surface Waves on Marine Sediments
TL;DR: In this paper, simple theoretical models are presented in order to investigate the dispersion of "Rayleigh" and "Scholte"-modes on ocean sea-floors, and the results show that in the presence of layers the Rayleigh as well as the Scholte wave splits up into a finite number of dispersive modes.