Layer 



Material 



Thickness, 

 m 



Depth, 



m 



Compressional 



Velocity, 



m/s 



Attenuation, 

 (dB/km)/Hz 



Density, 



g/cm^ 



Sea Floor 









R= 1.11 













Sfc 



1678 



0.5 



1.81 



1 



Clay, silt 

 and sand 



17 



2 

 17- 



1695.5 

 1751 



0.445 

 0.312 



1.81 



2 



Limestone 

 and chalk 





17+ 



2200 



0.02 



2.16 



Table 3.12. Straits of Sicily sediments — shallow model*. 

 *This model is appUcable to water depths shoal of 300 meters. 











Compressional 











Thickness, 



Depth, 



Velocity, 



Attenuation, 



Density, 



Layer 



Material 



m 



m 



m/s 



(dB/km)/Hz 



g/cm^ 



Sea Floor 









R= 1.07 













Sfc 



1623 



0.027 



1.52 



1 



Clay, silt 



500 



25 



1703.5 



0.0285 



1.55 





and silty 





50 



1721 



0.0295 



1.57 





clay 





100 



1739 



0.0315 



1.65 









200 



1757.5 



0.034 



1.78 









300 



1768 



0.034 



1.88 









400 



1776 



0.295 



1.95 









500- 



1782 



0.355 



2.01 



2 



Limestone 

 and chalk 





500+ 



2200 



0.02 



2.16 



Table 3.13. Straits of Sicily sediments — deep model. 



3.7 Shallow Bering Sea 



The Bering Sea has an extended amount of shallow water between 30 m and 

 100 m in depth. The region chosen for a site is located 56°-59°N, 165°-169°W (see 

 Figure 2.2). The sound speed profiles from this area were mostly between 50 and 100 m 

 in bottom depth. The data sample was divided into two seasons, October-March and 

 April-September. Results are summarized in Table 3.14. The small number of profiles 

 from the winter months is understandable due to the unhospitable weather conditions at 

 that time of year. However, each of those 13 profiles were positive gradient profiles. It is 

 very highly probable, if not 100 percent certain, that surface ducted sound speed profiles 

 will be found in the fall and winter months in the shallow Bering Sea. In contrast, only 

 13.4 percent positive gradient profiles were found during spring and summer. 



36 



