Tuesday, November 04, 2008

A sort of mini tsunami

This news in Boston Globe today by Megan Woolhouse is intriguing:
Dockworker Marcy Ingall saw a giant wave in the distance last Tuesday afternoon and stopped in her tracks. It was an hour before low tide in Maine's Boothbay Harbor, yet without warning, the muddy harbor floor suddenly filled with rushing, swirling water.

In 15 minutes, the water rose 12 feet, then receded. And then it happened again. It occurred three times, she said, each time ripping apart docks and splitting wooden pilings.

"It was bizarre," said Ingall, a lifelong resident of the area. "Everybody was like, 'Oh my God, is this the end?' " It was not the apocalypse, but it was a rare phenomenon, one that has baffled researchers. The National Weather Service said ocean levels rapidly rose in Boothbay, Southport, and Bristol in a matter of minutes around 3 p.m. on Oct. 28 to the surprise of ocean watchers. Exactly what caused the rogue waves remains unknown.

Here they call it the "rogue waves" again, which is certainly different from the kind of freaque waves commonly visualized in the open ocean.

"The cause of it is a mystery," said National Weather Service meteorologist John Jensenius, who first reported the waves from a field office in Gray, Maine. "But it's not mysterious that it happened."

Specialists have posed a variety of possible explanations, saying the waves could have been caused by a powerful storm squall or the slumping of mountains of sediment from a steep canyon in the ocean - a sort of mini tsunami. The last time such rogue waves appeared in Maine was at Bass Harbor in 1926.

Oh yes, "a sort of mini tsunami" would be a reasonably good descriptive expression.
Jeff List, an oceanographer at the US Geological Survey at Woods Hole said he and other researchers studied the occurrence, but no one has been able to pinpoint the cause. And he said similarly enormous waves appeared once on the Great Lakes.
Too bad he did not give any details about that enormous waves appeared once on the Great Lakes. As typical of modern day reporters, this one does not seem interested in asking about the details either. But the following by List is plausible:
A squall line surge, which occurs when fast-moving storm winds sweep over water that is traveling the same speed, can create such a wave. (The speed of waves is directly related to wind speed and the depth of the ocean at any given point.)
At any rate, every time something strange in the ocean happens, our academic world usually don't have an answer or explanation beyond pure speculation. But for a world that only go goo-goo gaga on empty non-issues like global warming, it will be a long time before the research world would spare any interest to pay attention to what's really happening in the world wide ocean, and that even includes the coasts of Maine and Massachusetts.

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