Browsing by Subject "Shear waves"
Now showing items 1-13 of 13
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A detailed study of sound reflections from a layered ocean bottom
(NATO. SACLANTCEN, 1965/05)The effect of layered sediments on sound reflection from the ocean bottom has been investigated theoretically and experimentally. Very detailed, systematic and computer-aided calculations of the reflection coefficient of ... -
A fast field model for three-dimensional wave propagation in stratified environments based on the global matrix method
(NATO. SACLANTCEN, 1986/03)A three-dimensional fast field program (FFP) model based on the global matrix method will be presented. Compared to traditional propagator matrix methods, the global matrix method allows for a more efficient, and, furthermore, ... -
Attenuation of shear waves in near-surface sediments
(NATO. SACLANTCEN, 1997)In situ measurement of compressional and shear speed and compressional attenuation in near-surface marine sediments is a well-developed technology but techniques required to measure shear attenuation have lagged behind. ... -
Estimation of shear wave properties in the upper sea-bed using seismo-acoustical interface waves
(NATO. SACLANTCEN, 1997)Acoustic interface waves have been recorded with a bottom deployed acoustic array at several locations. High resolution array processing technique (Prony) is used to estimate velocity versus frequency for the interface ... -
Instrumentation for crosshole geoacoustic measurements in unconsolidated sediments
(NATO. SACLANTCEN, 1994/06)Research tools are described that enable direct measurements of sediment properties as a function of depth in unconsolidat,ed sediments. The first tool is a hole making device that sits on the sea floor and utilizes pneumatic ... -
Interface-wave propagation studies: an example of seismo-acoustic propagation in non-homogeneous materials
(NATO. SACLANTCEN, 1990/01)This study addresses the problem relating to the interaction processes -
Relating in situ shear wave velocity to void ratio and grain size for unconsolidated marine sediments
(NATO. SACLANTCEN, 1997)Recent advances in field hardware have meant that it has become possible to measurein situ shear wave velocity in the upper few decimetres of sea floor sediment in a routine manner. It is known that shear wave velocity can ... -
Scattering from a rough sedimental seafloor containing shear and layering, as determined by perturbation theory
(NATO. SACLANTCEN, 1993/07)First-order perturbation theory is applied to reverberation from a rough sedimental seafloor. In addition to existing approaches, the seafloor is allowed to be shear-supporting or to be layered. Scattering strengths are ... -
Seabed sediment characteristics assessed geophysically: results of experiments in the Clyde Sea, Scotland
(NATO. SACLANTCEN, 1997)Within a research programme aimed at developing in situ sediment classification methodologies, it has been demonstrated that with only limited ground truth information, sub-bottom profiler data can be inverted to produce ... -
Shear properties of ocean sediments determined from numerical modelling of Scholte wave data
(NATO. SACLANTCEN, 1986/06)Recently it has become apparent that shear properties of ocean sediments are most easily determined from measured propagation characteristics of seismic interface waves. We use a newly developed numeri ca l model of wave ... -
Source and receiver responses in boreholes
(NATO. SACLANTCEN, 1997)This report considers the acoustic interaction between the acoustic freld rn a borehole and the elastic field in the surrounding formation. The problem with acoustic-seismic radration of energy from a source in a fluid ... -
The optimum frequency of propagation in shallow-water environments
(NATO. SACLANTCEN, 1983/04)The optimum frequency of propagation in shallow water environments is the result of competing propagation and attenuation mechanisms at high and low frequencies. It is shown that the optimum frequency is strongly dependent ... -
The use of Love waves to determine the geoacoustic properties of marine sediments
(NATO. SACLANTCEN, 1986/06)The importance of the geoacoustic properties of marine sediments for low-frequency shallow water propagation is well established. Reliable compressional properties can be obtained from laboratory analysis of collected ...