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White House Approves Sonic Cannons For Atlantic Energy Exploration 272

Posted by Soulskill
from the still-waiting-on-my-sonic-screwdriver dept.
An anonymous reader writes: The White House on Friday gave final approval to allow the use of sonic cannons in finding energy deposits underneath the ocean floor on the U.S. Atlantic seaboard. The Bureau of Ocean Energy Management says that finding energy resources off the Atlantic seaboard "could generate thousands of jobs, but has also acknowledged that the process will harm sea creatures." Sonic cannons "fire sound waves 100 times louder than a jet engine." Mammals such as whales and dolphins that communicate through sound will most likely be affected, but scientists aren't sure to what extent. They also aren't sure how the cannons will affect fish and other sea creatures or how any physiological effects on them may impact the fishing industries of the U.S. and the other countries who rely on seafood that migrate into and out of the Atlantic Ocean.
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White House Approves Sonic Cannons For Atlantic Energy Exploration

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  • by Anonymous Coward on Saturday July 19, 2014 @11:29PM (#47492029)

    I've heard a geologist speak of doing this in the Mediterranean. I would hope the experience would allow them to do more than speculate about the effects on animals.

  • by jenningsthecat (1525947) on Saturday July 19, 2014 @11:50PM (#47492123)

    When sonar is used, it can create sound pressure levels of 140dB 300 miles from the source [nrdc.org]. The sound is so excruciating that whales will surface too fast and get the bends, and/or beach themselves, just to escape the sound.

    Yup, let's rape our irreplaceable planet some more while torturing innocent, intelligent creatures. After all, they aren't human, and our comfort, convenience, and entertainment are so much more important than their lives.

  • by LynnwoodRooster (966895) on Sunday July 20, 2014 @12:33AM (#47492303) Journal
    Decibels used in SONAR are referenced to 1 microPascal; deciBels used in audio are referenced to 20 microPascals. Thus there is a 26 dB difference in level. A level of 140 dB underwater is the same as 114 dB SPL (in air). About a mid-level peak at an EDM club. Source: designing SONAR systems for scientific and fisheries research for the better part of a decade...
  • by Rei (128717) on Sunday July 20, 2014 @04:25AM (#47492891) Homepage

    286 db at source? Air cannons are 250 db at source, so 3 and a half orders of magnitude less powerful. Lightning in the ocean is 260 db at source and your average square kilometer of ocean gets two strikes per year. These ships will be covering tens of millions of square kilometers. With a pulse rate of once every 10 seconds (3.2 million pulses per year per ship, if they run constantly, which they almost certainly won't), you're looking at an order of magnitude less per ship than lightning (and I doubt there will be many ships, and they won't always be in operation). And lightning striking water is an order of magnitude louder. It even causes shock waves in the water by the same mechanism - rapidly creating an air bubble in the water (in lightning's case, by boiling the water) which then oscillates as it implodes and explodes repeatedly.

    Now, one could say that this is different because it's all in one place at a given time, and thus animals would be tempted to flee instead of it being a one-off thing. But then again, lightning strikes aren't spread out evenly over space and time either, they come in thunderstorms which do the exact same thing, repeatedly hitting the same section of sea for hours at a time.

    I'm not saying that I think these ships are harmless - not at all. I just think that I think people are overplaying it when they make these apocalyptic pronouncements on what effect they'll have on sea life. I mean, people have been detonating underwater *atomic bombs* - how do you think that compares to the sound of a pop of air? At 400 feet, a blue whale's own calls (188db @ 1m) are louder than the air gun.

  • Re:Other loud noises (Score:4, Informative)

    by Rei (128717) on Sunday July 20, 2014 @06:20AM (#47493125) Homepage

    Common screwup. Those are all atmosphere-rated decibel figures. Underwater decibel figures are listed at 61.5 dB louder than their atmospheric equivalents [dosits.org]. 250 dB underwater is 188.5 atmospheric.

    Adjusting your above examples to be underwater figures, we get:

    271.5 dB 2.0 earthquake
    296.5 dB 5.0 earthquake
    309.5 dB atom bomb
    371.5 dB loudest volcano

    I'd think it obvious that an air cannon isn't going to produce sound levels equivalent to an atomic bomb. And actually one would expect an underwater atomic bomb to be much louder than a surface one, far more of the energy is going to go into creating a gigantic oscillating bubble. And lastly, your cited atomic bomb figure is only for the 16 and 21 kiloton bombs that were dropped on Hiroshima and Nagasaki. Modern thermonuclear weapons are generally three orders of magnitude higher yield than that. A large thermonuclear weapon in deep water will create a bubble on the order of magnitude of a kilometer in size [dtic.mil], which will then oscillate in a series of collapses and reexplosions. The oscillating bubbles created by air cannons are practically microscopic by comparison.

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