3.3 East of Singapore 



The local area at the site East of Singapore, 0°-2°N, 105°-109°E, is located on the 

 chart in Figure 3.5. The site Ues on the Sunda continental shelf, east-southeast of Singapore 

 and west of the island of Borneo. This is an example of an equatorial shallow water environ- 

 ment which also is isolated from open ocean influences. Water depths are quite shallow, 

 varying from about 25 m to 75 m. The mean depth is taken to be 50 m. Few Nansen cast 

 data were available and the original area was expanded from 0°-l°N, 106°-107°E. Also 

 the data set was supplemented with a large percentage of XBT data. 



Figure 3.6 gives representative profiles for the two seasons. The months October 

 through March were processed as winter and April through September, as summer. From 

 Table 3.5, it is seen that 82.5 percent and 60 percent of the winter and summer profiles, 

 respectively, were classified as positive gradient profiles. 



The sediment properties for this site* are given in Table 3.6. The area is covered by 

 a 70-80 m layer of mud (silt-clay) overlying a harder sand-silt-clay layer about 1 10 to 1 20 m 

 thick. The underlying acoustic basement (layer three) is probably basalt. The whole area is 

 relatively flat except for some deeper areas near islands. 







Positive 



Positive 



Season 



Total 



Gradient, # 



Gradient. % 



Winter 



40 



33 



82.5 



Summer 



35 



21 



60.0 



Totals 



75 



54 



72.0 



Table 3.5. Summary of sound speed profiles for the site bast of Singapore. 











Compressiona! 











Thickness, 



Depth. 



Velocity, 



Attenuation, 



Density, 



Layer 



Material 



m 



m 



m/s 



(dB/km)/Hz 



g/cm^ 



Sea Floor 









R = 0,99 













Sfc 



1523 



.06 



1.45 



1 



Siit-clay 



78 



78- 



1617 



.07 



1.55 



2 



Sand-silt 



1 13 



78+ 



1830 



.07 



1.89 





clay 





141- 



1943 



.08 



2.02 



3 



Basalt 





191 + 



4200 



.03 



2.37 



Table 3.6. Sediment properties of the site East of Singapore. 



*The geoacoustic model was originally constructed for the one-degree square, 0°-l°N, 106°-107°E but 

 is considered valid over the expanded area. 



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