SOUND SPEED AND ABSORPTION STUDIES OF MARINE SEDIMENTS BY A RESONANCE METHOD—PART II

Geophysics ◽  
1960 ◽  
Vol 25 (3) ◽  
pp. 659-682 ◽  
Author(s):  
George Shumway
Keyword(s):  
Physical Properties ◽  
Marine Sediments ◽  
Sound Speed ◽  
Resonance Method ◽  
Unconsolidated Sediments ◽  
The Pacific ◽  
Absorption Studies ◽  
Harbor Sediments

The relationships between sound speed and the more important physical properties of unconsolidated sediments have become known in recent years largely as a result of the studies of Hamilton, 1956; Hamilton et al., 1956; Shumway, 1956, 1958; Nafe and Drake, 1957; Sutton, Berckhemer and Nafe, 1957; and Laughton, 1954, 1957. The suite of samples used in this study is larger and more varied than the suites used in any of the earlier studies, and the measurements probably were more carefully taken. A large number of shelf and harbor sediments were used in addition to sediments from deeper water in the Pacific and Arctic Oceans.

SOUND SPEED AND ABSORPTION STUDIES OF MARINE SEDIMENTS BY A RESONANCE METHOD

Geophysics ◽  
1960 ◽  
Vol 25 (2) ◽  
pp. 451-467 ◽  
Author(s):  
George Shumway
Keyword(s):  
Grain Size ◽  
Sound Speed ◽  
Absorption Maximum ◽  
Volume Fraction ◽  
Sea Water ◽  
Resonance Method ◽  
Unconsolidated Sediments ◽  
Linear Absorption ◽  
Average Value ◽  
Absorption Measurements

Laboratory measurements of compressional sound speed, and absorption, have been made on 111 unconsolidated marine sediment samples, ranging from shallow water sands to deep‐sea clays. In addition, determinations were made of porosity, wet density, and grain size distributions. Frequencies between 20 kc/sec and 37 kc/sec were used for the acoustic studies. Sound speed values at room temperature range from 1.474 km/sec for a red medium clay to 1.785 km/sec for a medium sand. More than one‐third of the values are lower than the value for sea water alone. Variations in the speed of sound in unconsolidated sediments as found in nature are caused by the following factors, in order of importance: (1) porosity, because of the great difference in compressibility of water and mineral grains; (2) the factor which produces rigidity, which appears to be related to the abundance of coarse grains; (3) pressure; (4) temperature; (5) compressibility of the grain aggregate, determined from compressibilities of individual minerals. Sound absorption measurements ranged from 0.5 db/m for a medium clay (28.4 kc/sec) to about 20 db/m for silts and fine sands (between 30 and 37 kc/sec). An absorption maximum occurs for sediments of intermediate porosity (0.45–0.6) and intermediate grain size (0.031 mm–0.25 mm). The expression [Formula: see text], where α is the linear absorption coefficient, M is a frequency‐dependent factor related to the sediment volume fraction of grains in mutual contact, and [Formula: see text] is a computable total acoustically effective grain surface area, predicts the absorption values and the absorption maximum. Absorption measurements at more than one frequency between 20 kc/sec and 37 kc/sec were obtained for 65 samples. Assuming that absorption is directly proportional to frequency raised to a power n, the data yield an average value of n equal to 1.79, with a standard deviation of 0.98.

Frequency dependence of sound speed and attenuation in marine sediments

2006 ◽  
Vol 120 (5) ◽  
pp. 3099-3099
Author(s):  
William M. Carey ◽  
Ji‐Xun Zhou ◽  
Allan D. Pierce
Keyword(s):  
Frequency Dependence ◽  
Marine Sediments ◽  
Sound Speed

A DEEP‐SEA ELECTRICAL RESISTIVITY PROBE FOR MEASURING POROSITY AND DENSITY OF UNCONSOLIDATED SEDIMENTS

Geophysics ◽  
1969 ◽  
Vol 34 (4) ◽  
pp. 554-571 ◽  
Author(s):  
A. Kermabon ◽  
C. Gehin ◽  
P. Blavier
Keyword(s):  
Electrical Resistivity ◽  
Marine Sediments ◽  
Unconsolidated Sediments ◽  
Formation Factor ◽  
Sea Floor ◽  
Polynomial Curve ◽  
Best Fit ◽  
Porosity Measurements ◽  
Probe Measurements

A study has been made of the mass physical properties and electrical resistivity of marine sediments. The well‐known linear correlation of density with porosity was confirmed. A third‐degree polynomial curve was found to be the best fit for our data relating porosity and the formation factor, which is the ratio of the bulk resistivity of marine sediments, to the resistivity of interstitial water. An electrical resistivity probe has been devised to obtain “in‐situ” profiles of resistivity versus depth. The instrument is 13 m long and weighs 700 kg in water. About thirty rapid measurements on the sea floor can be made in one lowering. Good correlation was obtained between electrical probe measurements and direct porosity measurements made on cores taken nearby.

scholarly journals Modelling acoustic scattering, sound speed, and attenuation in gassy soft marine sediments

2016 ◽  
Vol 140 (1) ◽  
pp. 274-282 ◽  
Author(s):  
A. Mantouka ◽  
H. Dogan ◽  
P. R. White ◽  
T. G. Leighton
Keyword(s):  
Marine Sediments ◽  
Sound Speed ◽  
Acoustic Scattering

Remote acoustic classification of marine sediments with application to offshore Newfoundland

1983 ◽  
Vol 20 (7) ◽  
pp. 1195-1211 ◽  
Author(s):  
N. A. Cochrane ◽  
A. D. Dunsiger
Keyword(s):  
Marine Sediments ◽  
Classification Scheme ◽  
Spatial Coherence ◽  
Unconsolidated Sediments ◽  
Limited Area ◽  
Acoustic Source ◽  
Shallow Marine Sediments ◽  
Correlation Properties ◽  
Acoustic Classification

Shallow marine sediments can be remotely classified by the spatial correlation properties of their seismic reflection signatures provided one uses a highly repetitive broadband acoustic source. A classification scheme defined by three spatial coherence parameters is shown capable of automatically differentiating between several formations of unconsolidated sediments in a limited area of offshore Newfoundland. The consistency and generality of the technique are explored and comparisons with standard echogram interpretation are made.

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