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Chances of large Delmarva quake 'are very remote'

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January 17, 2010

Hurricanes, flooding and snowstorms present far greater natural threats to Delaware residents than the devastation of earthquakes and tsunamis. And with millions reeling from killer quakes in Chile and Haiti this year, the question arises again: Could that happen here?

Wise scientists -- including Stefanie Baxter of the Delaware Geological Survey -- seldom say "impossible." "Anything is possible," Baxter said Saturday evening, "but the chances are very remote."

The largest earthquake in recorded Delaware history was a magnitude-4.1 quake that caused minor property damage in 1871. A magnitude-2.8 quake raised eyebrows last summer. But this is not a hotbed of quaking plates.

The stressors that cause earthquakes in this area come from the Mid-Atlantic Ridge, a boundary of tectonic plates that stretches down the length of the Atlantic Ocean, hundreds of miles offshore. Tectonic plates are large pieces of the earth's crust, solid rock, that shift and move and can be up to 60 miles thick, according to the U.S. Geological Survey. When the plates along the Mid-Atlantic Ridge move, they activate the small faults that produce earthquakes here, Baxter said. Though the faults that affect this area are hidden or buried, they are still here, though not visible like California's San Andreas Fault. Where there are earthquakes, there are faults, Baxter said.

The plates along the Mid-Atlantic Ridge are moving apart, she said. The plates in the Pacific region now experiencing earthquakes are moving together, one going beneath the other. Earthquakes occur routinely around the world, most of them underwater, in remote areas or too small to cause distress.

Among the scores of global earthquakes that exceeded 5.0 magnitude Saturday -- most of them in or near Chile after its massive 8.8 quake -- was an earthquake of magnitude 5.4 along the Northern Mid-Atlantic Ridge about 900 miles northeast of Brazil, according to data from the U.S. Geological Survey.

The quake activity in the Pacific and Caribbean regions do not signal any increased likelihood of activity in the Atlantic, Baxter said. But the developments do provide an opportunity for all to consider the risks that do exist here, said sociologist Tricia Wachtendorf, associate director of the Disaster Research Center at the University of Delaware, who has studied earthquake and tsunami response around the world.

"We just had a severe winter snowstorm through the area, and some are at risk for flash flooding," she said. "There is a hurricane risk in this region. These are the events much more salient to us. It's a good time to think about how to make our households safer. Do we have supplies on hand if a disaster were to happen? What is our plan in terms of evacuation? "It's also an opportunity to think about our communities and those who are more vulnerable, who may not have access to transportation or may rely on different sources of information." Wachtendorf said she was impressed by the response to the Pacific tsunami warnings in Hawaii Saturday -- that residents weren't panicking, but they were preparing.

"That's exactly how things should turn out," she said.

Though Delaware residents face no major earthquake threats, they have responded quickly to those who have been devastated. Two teams of Delaware medical professionals are to return today after a week of assisting earthquake victims and others needing care in Haiti, where a magnitude-7.0 earthquake on Jan. 12 killed thousands and left at least a million without homes.

About a dozen volunteers each from Alfred I. duPont Hospital for Children and the Delaware Medical Relief Team worked in the areas of Port-au-Prince and Jacmel, respectively. Dr. Vinod Kripalu, one of the directors of the DMRT who expects to travel to Haiti with another team in late March, said team members talked about the earthquake in Chile Saturday. For the next four to six weeks, though, the team will continue its focus on the acute needs in Haiti, he said.

For questions and information, contact DGS at
delgeosurvey@udel.edu, 302-831-2833
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