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Geotimes
 Published by the American Geological Institute
Newsmagazine of the Earth Sciences

 July 2000


News Notes
 Natural Hazards

Tsunami news floods East Coast

Terror. Threat. Speeding waves. Tsunami. These words hit news headlines like the Sunday paper hits your doorstep.

Whump.

All you wanted was the midweek paper, coffee and 15 minutes of early morning peace.

You swallowed a little more than French Roast if you picked up USA Today on May 2 or The Washington Post or The New York Times on May 3.  Tidings of impending destruction from a possible  East Coast tsunami swept the headlines. The fear of a killer wave striking the Mid-Atlantic coast crossed the gap between the usual not-in-my-backyard dismissal and the mind-blowing notion that the Washington Monument might be bobbing down the Potomac River like a drifting buoy sometime in the near future.

Neal Driscoll of the Woods Hole Oceanographic Institution, and fellow researchers John Goff of the University of Texas and Jeffrey Weissel of the Lamont-Doherty Earth Observatory, discovered inexplicable crack-like features on the continental shelf off the coast of southern Virginia and North Carolina.  They published their findings in the May issue of Geology

From sidescan images and bathymetric profiling the scientists identified what they described as en echelon cracks spanning 40 kilometers in water depths of 100 to 200 meters. Directly to the south of the cracks was a sediment slump that formed after the Ablemarle-Currituck slide during the Pleistocene. They drew attention to the juxtaposition of the two features as evidence for potential slope failure in the vicinity of the newly discovered cracks. In their Geology article they concluded that, “Given the risk to the coastal community, it seems wise to invest effort to determine whether the en echelon cracks … are fossil features or are active and likely to produce a potentially disastrous, large submarine slide in the near future.”


     Lead researcher Neal Driscoll (bottom left) helped prepare the gravity corer to take sediment samples. The samples were scheduled for analysis to determine the origin of sediment-trapped gas off the coast of Vriginia and North Carolina. 
From the Woods Hole Oceanographic Institution.

On May 6, Driscoll and fellow researchers left for a two-week research cruise to further investigate the sea-floor cracks. What at first appeared to be cracks now seem to be craters that formed as a result of massive gas blowouts. Sonar studies of the geometry of the subsurface did not reveal fault lines as the team had expected, but rather large pockets of gas trapped in the sediment.
 

    CLICK HERE FOR A LARGER IMAGE.
Instead of answering questions related to sediment slumping along cracks, Driscoll and his team opened an entirely different can of worms. “We found areas of sediment that are bowed up from gas charging in the sediments,” he says. In light of these new discoveries, Driscoll questions whether or not the Ablemarle-Currituck slide 40 kilometers to the south could have been generated by a gas blowout and plans to investigate the area further before making any definite conclusions.

Driscoll does not discount the possibility that this area still poses a tsunami threat. “There is a slight potential for slope failure,” he says. If gas blowouts are related to the sediment slumping at Ablemarle-Currituck, then there is reason to believe that it could happen again, he says

Goff agrees.  “There are physical features that could lead to a major event such as a tsunami, but the chances of that happening are slim,” he says, “We are not worried about it taking place in our lifetime.”

How did the report published in Geology become a feeding-frenzy for newspapers across the East Coast?

As they do with every issue, the editorial staff of Geology sent out an e-mail summarizing the contents of the May issue a few days before May 1. Geology didn’t provide a press release, but Woods Hole, Lamont-Doherty and the University of Texas did. All three releases highlighted the potential for a damaging tsunami to strike the Mid-Atlantic region of the United States in the near future.

The story was covered in The New York Times, The Seattle Times, Chicago Tribune and Los Angeles Times — just to name a few. “Ocean crack could spawn tidal waves,” headlined USA Today. The front page of  The Washington Post on May 3 read: “Wave of concern: Atlantic tsunami? Fissures found off Va. Coast may be precursor, experts say.”

The news washed into the evening broadcasts of MSNBC and Comedy Central’s The Daily Show, according to Ann Cairns, director of communications and marketing for the Geological Society of America, which publishes Geology. “We knew it would get a lot of attention, but we were taken aback by how much attention it received,” Cairns says.

“We haven’t made predictions or statements that have led to sensationalization of our work,” Driscoll says. “We were stunned when we put out the first press release.”

“The media jumped the gun,” says Costas Synolakis, director of the Tsunami Research Group at the University of Southern California. Although he agrees there is indeed cause for investigation, his initial reaction was that the report had been sensationalized by a whirlwind of media coverage.  As Driscoll and his team have realized, Synolakis says, “if it does have potential, there are many other factors to be considered, including dating other slides in the area.”

However, Synolakis does not claim that the coverage was unnecessary. “I agree that the issue does need coverage. Offshore hazards were not recognized before the Papua New Guinea project,” he adds. “This has been a wake-up call. There is something out there that could pose a hazard to populated areas.”
 

Laura Wright



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