TABLE 8. LABORATORY MEASUREMENTS OF SEDIMENT SOUND 

 VELOCITY CORRECTED TO IN SITU VALUES 





Laboratory 





In Situ 





Sample 

 No. 



Sound 



Velocity (1) 



(m/sec) 



Porosity 

 (%) 



Temp. (2) 

 (°C) 



Pressure (3) 

 (kg/cm 2 ) 



Porosity (4) 



Sound 



Velocity (5) 



(m/sec) 



GGC-3 



1496 



80.9 



1.6 



369.2 



80.9 



1484 



EM8-1 



1513 



71.8 



5.6 



372.3 



69.9 



1505 



EM8-9 



1559 



73.1 



12.3 



377.3 



70.6 



1593 



EM8-10 



1533 



80.1 



13.5 



378.2 



78.8 



1568 



EM8-11 



1537 



76.8 



14.8 



379.2 



75.8 



1578 



EM8-12 



1530 



70.5 



16.1 



380.2 



67.4 



1580 



EM8-13 



1533 



-r 



17.3 



381.2 



-- 



1587 



EM8-14 



1518 



74.6 



18.8 



382.3 



72.6 



1573 



EM8-15 



1522 



75.6 



20.3 



383.4 



71.6 



1584 



NOTES: 



(1) Measurements by resonance technique: samples EM8-9, -11, -14, -15, ±10 m/sec; 

 pulse technique: samples GGC-3, 8-1, -10, -12, -13, ±3 m/sec; referred to 

 common temperature of 22.8°C; GGC is Guadalupe Gravity Core. 



(2) Measured: m situ sediment surface temperature with increment from gradient (see p. 31 



(3) Hydrostatic (pore water) pressure, water surface to sample level; from Wilson (Table IX, 

 10° portion for sediment). 50 



(4) From sample consolidation curves. 9 



(5) Laboratory value plus (or minus) the sum of velocity corrections: temperature in lab. 

 (22. 8°C) to that in hole : pressure of 1 atmosphere to that in hole; and decrease in 

 porosity, lab. to in situ. 



Results and Conclusions 



SOUND VELOCITY CORRECTIONS, LABORATORY TO IN 



SITU 



While the laboratory sound- speed measurements are 

 of interest, the important aspects of the investigation re- 

 quire that estimates be made of the vertical sound-velocity 

 profile in the sea floor. A study was recently completed 

 in which the bathyscaph TRIESTE was used to measure 

 sound velocities in the surficial sediments off San Diego in 

 water depths to 1235 meters, 5 Cores taken from the 

 TRIESTE at the same places were examined in the labora- 

 tory to determine the proper corrections to apply to 

 laboratory measurements to get good estimates of in situ 

 sound speeds. These studies showed that predictions with- 

 in 1 percent accuracy are possible if full temperature and 



29 



