UMaine professor: Earthquakes aren’t linked

Posted March 11, 2010, at 10:10 p.m.

ORONO, Maine — Haiti on Jan. 12. Chile on Feb. 27. Turkey on Monday. Chile again on Thursday.

Earthquakes and aftershocks have rocked several areas of the world in the past 2½ months.

Is there a reason for seemingly increased earthquake activity, and could a significant quake hit Maine?

Aside from last month’s 8.8 magnitude earthquake in Chile, it seems the recent spate of quakes is nothing out of the ordinary, said Peter Koons, a University of Maine professor of geodynamics.

“The answer is that quakes are all driven by the movement of tectonic plates, and the activities are not directly connected,” he said Thursday, a few hours after Chile reported a 6.9 magnitude quake. “One earthquake in Haiti does not influence those in Chile, but the Chilean series are connected.”

Koons said the strong aftershocks in Chile are expected as the tectonic plates along the plate boundary reorganize and settle after the massive Feb. 27 earthquake.

“There was a huge displacement associated with that big quake, and that propagates up and down the plate boundary,” he said. “Anytime we have a large failure along one of these big plate boundaries, we tend to have a number of other large quakes associated with it.”

The magnitude 7.0 Haiti quake and the magnitude 6.0 Turkey quake were more standard seismic activity. Koons said Turkey is capable of producing much larger quakes.

The level of death and destruction in those quakes, he added, was more notable than the intensity of the seismic activity itself.

Scientists likely will never be able to predict the precise time and size of an earthquake, although the Haiti quake was forecast before the event, Koons said.

Nations would be better off to put time and money into solid construction, he said, which is already done in relatively wealthier places such as the United States, Japan, and Koons’ native New Zealand, which Koons said is similar to California in its level of seismic activity.

“We can identify where [earthquakes are] most likely [to be] and that’s relatively well done,” he said. “The places that put resources into expecting there’s going to be a quake do so to protect life, if not infrastructure.”

Many Mainers have experienced small shakes themselves, but we need not worry here, for the most part.

Henry Berry, a geologist with the Maine Geological Survey, said the state’s strongest recorded quake was measured at magnitude 4.8 and occurred in 1973 in Bowmantown Township. In 1904, before instrumentation was used in Maine to measure quakes, a quake of a Level VII intensity hit the Eastport area.

Berry said that might translate to a magnitude 5.9 earthquake.

Both Koons and Berry said the area around the St. Lawrence River, however, has potential for stronger quakes.

“Earthquakes in the eastern half of the continent are unpredictable and rare, but every once in a while there’s a big one that will come out of nowhere,” Berry said. “The probability is low, but not zero.”

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