From: jack.bohn64@gmail.com   
      
   Noise from the flow of the water?  My brother lives a few miles (kilometers)   
   from the Delaware River, on a tributary.  During spring flooding, the roiling   
   against the pilings of the local bridge can be heard for the high hundreds of   
   meters, maybe more    
   than a kilometer.  A fast-fill model would probably leave many obstructions.    
   How that would scale, I don't know.  Looking at a map, his bridge looks to be   
   about 200m long, while the straits of Hercules looks to narrow to about 20km.    
   Say 100 times the    
   surface to make the noise, so 100 times louder?  Say distance increases with   
   the square root of intensity, you'd hear the babbling of the Hercules river   
   from 10 km away.   
      
   ...Or are we talking a Gibraltar Falls scenario?  Perhaps a comparisson to   
   Niagra rather than the Amazon would be in order.   
      
   To throw out numbers, Amazon discharges 209 thousand cubic meters/second,   
   Niagra 2.4 thousand cubic meters/second, or 1/9 Amazon.  You say the   
   Mediterrainian fill flow could be 1000 Amazons, that's 9000 Niagras.  Would it   
   be 9000 times as loud?  Depends,    
   I guess.  (For maximum sound, I would think the best design would be a series   
   of cataracts, each long enough for the falling water to achieve terminal   
   velocity.)  That gives us a square root of 90.  There are anecdotes of hearing   
   Niagra Falls from 24 to    
   32 km away, but that is when the wind is right and everyone shuts up; for no   
   good reason, I'll say at half that, 12 km it's noticeable.  IF Gibraltar Falls   
   sounds the same 90 times further away, thats 1000 km, which covers all of   
   Spain.  I have no    
   scientific reasoning behind it, but that's not a number I can believe in.  But   
   it does bring up the earth shaking.   
      
   A month ago there was a YouTube video about making artificial earthquakes with   
   a four-tonne steel ball: for early seismological tests they would drop it 14   
   m.  Alas, it doesn't give a corresponding reading, and that would be more   
   research than I'll do    
   for a stranger.  (Besides, as you can see, anything I'd extrapolate from that   
   would have a margin of error larger than the number I'd get.)   
      
   Just a side thought: 209 thousand thousand cubic meters per second.  The 20 km   
   wide strait, say 10.45m deep, roughly rectangular, that's 209 thousand square   
   meters right there, a kilometer-long slug of that has to pass in a second?    
   Have I slipped a    
   digit somewhere?  Can we have a supersonic river?   
      
   Whatever the flow rate, how big a menace to oceanic navigation would this be?    
   Would Atlantic-facing beaches north and south see sideways currents across   
   them?  Cyclonic and anticyclonic whirlpools?   
      
   --    
   -Jack    
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)