[Link: www.popularmechanics.com...]

The problem, he says, is that the pictures of this roughly 190-foot-wide disk-shaped formation were taken using side-scan sonar, a relatively inexpensive type of sonar technique useful for finding sunken ships. However, the images themselves reveal several distortions that render them virtually useless for identifying an undersea formation, Singh says.

First, he says, if you look carefully, you can see a reflection of the circular formation on the right side of the image. Since side-scan sonar is taken with two instruments that bounce acoustic waves in opposite directions from the boat, a feature on one side shouldn’t affect the image on the other side. “This means you’ve got ‘cross-talk,’ in which one channel is electrically contaminating the other,” Singh says. In other words, the sonar instruments aren’t wired properly. Strike one, he says.

Strike two: The black horizontal lines going through the image show that sonar signals are dropping out (that is, the instruments aren’t detecting them), further calling the measurements into question, Singh says. Finally, he says, the edges of the image, just beyond the circular formation, are gray, meaning the sonar couldn’t tell what was there. That shows the sonar isn’t calibrated well enough to trust, Singh says. “That’s strike three.”

Charles Paull, senior scientist at the Monterey Bay Aquarium Research Institute in Moss Landing, Calif., says that even if the formation were real, it could be something as mundane as a circular rock outcropping or the result of fluid or gas venting. Such venting causes inexplicable and poorly understood structures like pockmarks—circular depressions that Paull has seen all around the world. In one area off California alone, he says, he has mapped more than 1400 such pockmarks.