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Tue July 9, 2013
Investigating Rhode Island's Tsunami
Scientists are still trying to understand what caused ocean levels across the state to fluctuate last month without warning. The event remains a relative mystery, but a group from the University of Rhode Island’s Graduate School of Oceanography believes it may have been a tsunami.
The author H.P. Lovecraft wrote: "But more wonderful than the lore of old men and the lore of books is the secret lore of the ocean." Such is the case in this story. It starts on June 13th, when Chuck Ebersole had a really unusual day. He's a Steward at the Wickford Yacht Club.
“Ok. Peter, I’m going to need your stern line too,”
He spends his day helping skippers moor their boats to the dock.
It was on day like this one, quiet and calm, that he noticed the water suddenly change. The current picked up. And the water rushed out of the harbor. Then he heard a pop. Pops are never good.
“Well, it sounded like,” he said. “It sounded a little like a board ripping. This Pshooow!”
The current had ripped a cleat from the dock. It was one of two mooring a sailboat, leaving it dangling on one line. Ebersole and others raced in and secured the boat. And then, something unexpected happened: the water that was rushing out… started to rush back in.
“I’ve never seen anything like it,” he said.
Word of the ocean acting strangely quickly reached North Kingstown Harbormaster Ed Hughes. He and others abandoned a harbor commission meeting to see what was happening at the Yacht Club.
“I got down there at pretty much the end of it,” he recalls. “But I could see where the boats were still being pulled, like with a lot of pressure, being pulled from where they were.”
He said the water went in and out, in and out, at an eight to nine knot clip.
“That’s a lot,” he said. “That’s a lot of water rushing by, I mean, for it to take a rope and a cleat off a dock, which is an amazing amount of pressure, and it just popped it off like it wasn’t there.”
Hughes, Ebersole and others watched the water oscillate in the harbor for the next 45-minutes or so.
“It was just so unique to see it,” he said. “I mean we was five of us just shaking our head going, ‘This is different.’”
News of the curious occurrence at Wickford Harbor made its way to scientists at the University of Rhode Island's Graduate School of Oceanography. Professor of Geophysical Fluid Dynamics, Chris Kincaid, said they quickly pulled up data from the National Oceanic and Atmospheric Administration. It has instruments that measure tide, wind and current changes all along the east coast. Sure enough, the gauges from North Carolina to Maine showed an anomaly.
“And right about at low tide on this day, on June 13th, the water level just drops right off the table,” he said, pointing at a print out of the tide gauge.
Kincaid said the drop, and corresponding rise in water level was tsunami-like. But fellow geologists looked at seismic records. Nothing. So Kincaid said a peer who studies atmospheric and ocean interaction pulled up weather data for the day. Bingo. NOAA had numerous reports of a severe weather system charging across Mid-Atlantic States. That weather system was a phenomenon known as a "derecho."
“I’ve heard people describe them as beautiful, and incredibly scary,” he said.
NOAA defines a Derecho as a long band of thunderstorms that cause damage in just one direction, over what amounts to a straight swath. They’re fairly common. NOAA even keeps a list of the 20 or so worst Derechos in recent history. They have names like, “The Corn Belt Derecho of 1998,” or “The People Chaser Derecho of 2001.”
But when this one slammed into the ocean, Kincaid and fellow scientists believe it may have caused a meteotsunami.
“Yeah, a meteotsunami,” he said. “Which is related to a meteorological induced tsunami.”
Or simply put a weather-generated tsunami. Essentially, high pressure winds from the De-REY-cho pressed down on the ocean. And the ocean responded with tsunami like waves. To demonstrate this, Kincaid fills up a Tupperware container part-way with water. Then he blew straight down on its surface.
His breath caused a depression. And when it released, the water went off as waves. The same thing, on a much larger scale could have happened in the Mid-Atlantic. This meteotsnumai theory is a popular one that’s out there. It makes scientific sense, and there’s empirical data to back it up.
What if it was something completely else though? I asked.
“Yeah,” he said. “And that’s another good point is that there are other possibilities. And so one of the possibilities is that the wind is not what produced the tsunami. But what maybe it produced was a landslide.”
Kincaid said that tsunamis can also occur after underwater landslides, or slumps. And the head of NOAA’s tsunami program, Mike Angove, said it’s investigating the possibility of this happening in the Hudson Canyon off the New Jersey Coast. NOAA has a buoy in deep waters in that location. Angove said it recorded a significant change in ocean level, which seems to indicate a slump.
“If it were a weather induced tsunami, you wouldn’t necessarily expect for it to, to register at that dart buoy which is located in very deep waters,” he said.
NOAA dispatched its research vessel, Okeanos Explorer to the area. It gained notoriety searching for shipwrecks in the Aegean and Black Seas. And it used multi-beam sonar to take detailed images of the Hudson Canyon. NOAA will compare those images with ones taken the previous year to look for any changes. But Angove said he’s unsure if they’ll find anything. He said the area is basically mud, making it difficult to spot slumps. And if nothing is found, then they’ll have to go back to the possibility of the meteotsunami. He adds that no definitive answer will be made until scientists can model it.
“That’s always the difficulty is that you need to be able to model this in a way that the waves represent what actually happened,” he said.
Angove said he hopes the studies will happen, as it’s important for coastal communities to prepare for such events.
North Kingstown Harbormaster Ed Hughes isn’t so sure scientists will ever find out what caused the water to rise and fall at Wickford Harbor.
“I’m willing to bet you that, the bottom line is going to be, ‘We think this is what it was.’ You’ll never get an answer for this one. And don’t think you’ll ever get an answer,” he said. “And that makes it way cooler.”
Hughes said the unanswered questions are what make this whole story ocean. He said it’s just another little secret the deep blue is keeping, adding to its wonderful lore.