VELOCITIES OF COMPRESSIONAL AND SHEAR WAVES IN MARINE SEDIMENTS DETERMINED IN SITU FROM A RESEARCH SUBMERSIBLE

DURING THE DEEP-SUBMERGENCE PROGRAM OF THE NAVY ELECTRONICS LABORATORY DIVES WERE MADE TO MEASURE, IN SITU, THE VELOCITIES AND ATTENUATIONS OF COMPRESSIONAL WAVES AND THE VELOCITIES OF STONELEY WAVES FROM WHICH SHEAR-WAVE VELOCITIES CAN BE CALCULATED. THE AMOUNT OF EQUIPMENT REQUIRED FOR BOTH SETS OF MEASUREMENTS PREVENTED MAKING COMPRESSIONAL-WAVE AND STONELEY-WAVE MEASUREMENTS DURING THE SAME DIVE, BUT AN ATTEMPT WAS MADE TO OCCUPY STATIONS CLOSE TOGETHER AND IN THE SAME SEDIMENTARY ENVIRONMENT. SEDIMENT SAMPLES WERE TAKEN AT EACH STATION AND ANALYZED IN THE LABORATORY FOR DENSITY, POROSITY, AND GRAIN SIZE. THESE DATA ALLOWED EVALUATIONS OF MODELS AND EQUATIONS, AND COMPUTATIONS OF CONSTANTS FOR ELASTIC AND VISCO-ELASTIC SATURATED POROUS MEDIA. IT WAS CONCLUDED THAT EITHER HOOKEAN INELASTIC OR VISCO-ELASTIC EQUATIONS CAN BE USED TO COMPUTE COMPRESSIONAL-WAVE AND SHEAR WAVE VELOCITIES AND OTHER ELASTIC CONSTANTS. FOR FOUR OF THE STATIONS, COMPRESSIONAL-WAVE VELOCITIES AND DENSITIES WERE MEASURED, AND SHEAR-WAVE VELOCITIES WERE CALCULATED FOR MEASURED STONELEY-WAVE VELOCITIES. USING THESE VALUES IN THE CLASSIC EQUATIONS OF ELASTICITY, VALUES OF SEDIMENT BULK MODULI, RIGIDITIES, LAME'S CONSTANTS, AND POISSON'S RATIOS WERE COMPUTED. IN THE VISCO-ELASTIC MODEL THE MECHANICS OF ABSORPTION ARE NOT SPECIFIED AND THE ASSUMPTION OF FREQUENCY INDEPENDENT COMPLEX LAME CONSTANTS LEADS TO A LINEAR DEPENDENCE OF ATTENUATION ON FREQUENCY AND NO DISPERSION OF VELOCITY WITH FREQUENCY IN THE RANGE OF FREQUENCIES OF INTEREST IN UNDERWATER ACOUSTICS AND MARINE GEOPHYSICS. THESE STUDIES AND OTHERS INDICATE THAT ALMOST ALL OCEAN SEDIMENTS HAVE FINITE RIGIDITIES AND TRANSMIT SHEAR WAVES.

  • Supplemental Notes:
    • Vol 75, No 20, PP 4039-4049, 3 FIG, 2 TAB, 33 REF
  • Authors:
    • Hamilton, E L
    • Bucker, H P
    • Keir, D L
    • Whitney, J A
  • Publication Date: 1970-7-10

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  • Accession Number: 00235776
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 26 1970 12:00AM