at least the time of Shakespeare, people have been talking about the Bermuda
Triangle, the area of the Atlantic between Miami, San Juan, Puerto Rico and
Bermuda, where an anomalously high number of ships and planes have reportedly
gone missing. Perhaps the most famous disappearance involves Flight 19, a World
War II Navy Avenger squadron that disappeared in the region during a routine
training mission off the coast of Florida. To this day, the five planes have
not been located, nor do people know why they disappeared. But Flight 19 and
others can all be explained by reasonable science, says Bill Dillon, a geologist
emeritus with the U.S. Geological Survey (USGS) in Woods Hole, Mass.
Five Navy Avengers similar to those pictured here disappeared in the Bermuda Triangle on Dec. 5, 1945, during a routine training mission. Nothing was ever found of the planes or the crew. Courtesy of the Naval Historical Center.
This region, which is not recognized by the U.S. Coast Guard as a geographic
area of specific hazard to ships or planes, is known for wild and sudden storms,
hurricanes and water spouts, the strong and turbulent Gulf Stream, and interesting
seafloor topography, going from a gently sloping continental shelf to a deep
drop-off, Dillon says. Additionally, many recreational boats and small planes
traverse the region, so its not surprising at all that many ships
go down there, he says. But another more speculative explanation has come
into the scientific discussion lately: that giant gas bubbles could be rising
from the deep and swallowing ships whole.
In the early 1980s, geologist Richard McIver published an article in the AAPG Explorer suggesting that methane hydrates a crystalline solid of methane gas and water, similar to ice (see sidebar) on the ocean floor could break apart and release giant methane gas bubbles that could cause ships or airplanes to sink or explode. The article was sort of tongue-in-cheek, Dillon says, but the explanation for the disappearances in the Bermuda Triangle struck a chord and quickly propagated through the media. And because most geologists might go so far as to say it is conceivable, Dillon says, the explanation has stuck around, despite some inherent flaws.
Methane hydrate is located in great volume all over the world, mostly on continental margins in the ocean or in permafrost in the Arctic, in places where the cold sea or land temperatures and extensive pressures hold them stable. Mapping has shown vast hydrate deposits off the East Coast of the United States from New Jersey to Georgia, although few, if any, in the actual area of the Bermuda Triangle, Dillon says.
The hydrate hypothesis for the Bermuda Triangle is that some trigger, such as an undersea landslide, would cause hydrate deposits to break apart and release a tremendous gas bubble. That burp would reduce the density of water and, when it hit the sea surface under a ship, would cause the buoyancy of the ship to decrease and thus sink, says Bruce Denardo, a physicist with the Naval Postgraduate School in Monterey, Calif. With airplanes, possibilities include that as the methane gas cloud rises through the air, the heat from the engines of an airplane flying through it would cause the cloud to ignite and thus incinerate the plane, or that the methane would replace enough oxygen in the air to cause the engines to quit.
The sinking of ships by turning the ocean to froth is certainly physically possible, Dillon says. But that possibility does not speak to chance or probability, says Bill Durham, a geophysicist at Lawrence Livermore National Laboratory in Livermore, Calif., who believes that the methane hydrates explanation is as good as any other but wouldnt bet on it. The thing is, when geologists say something is plausible, theyre talking about on the geologic time scale, he says.
And indeed, submarine landslides have released large methane clouds in the past about 13,000 years ago, says Debbie Hutchinson, a geologist at USGS in Woods Hole. Back then, sea level was much lower than it is now, which lowered the pressure on hydrate deposits and may have allowed them to melt and release gas. The high pressure exerted on the deposits in the last several thousand years from rising sea levels acts to stabilize them.
While hypothetically I think bubbles could release and cause boats to sink, the likelihood is so remote that it just cant explain the disappearances in the Bermuda Triangle, Hutchinson says. To sink a ship, it would have to be floating at just the right spot at just the right time. Furthermore, she says, as remote a possibility as it is that one boat would encounter a bubble and sink, the probability is even lower that such a phenomenon could cause more than one disappearance.
Another problem with the methane hydrate explanation, Durham says, is that methane gas released from a trap below the hydrate deposits would likely dissolve in the ocean water before reaching the surface. And, Dillon adds, if disturbed enough to break apart, the deposits themselves would likely float to the surface and then very slowly release gas, not in an explosive bubble.
Beyond the geology issues, there are also physics issues, says Denardo, who says as an educated member of the public, he just doesnt see enough evidence to believe in the Bermuda Triangles deadly mystery. He has performed tests on floating objects to determine the amount of bubbles needed to sink a ship. Fluid dynamics is enormously complicated, he says, and sinking a ship by reducing the buoyancy requires a vast amount of bubbles, especially because the bubbles may additionally cause an upward force on the ship, making it more difficult to sink. The ocean is much more complicated than our laboratory experiments, Denardo says.
Finally, Hutchinson adds, it is important to note that official records of shipwrecks and disappearances indicate no statistically higher incidence of wrecks in this region than in other regions worldwide. Thus, perhaps no unique explanation is necessary.
The Bermuda Triangle is a fairy tale, Dillon says. The story got into the public mind, and its one of those things that just keeps coming up every few years, like aliens with egg-shaped heads swooping down to Earth to abduct people, he says. I would rather believe in aliens with egg-shaped heads than in a gas bubble from hydrates sinking ships and planes in the Bermuda Triangle. But of course, he adds, I dont believe in either tale.