Know your faults: Illinois' earthquake risk

February 15, 2010 10:31:49 AM PST
What caused Wednesday's earthquake? And is it likely to happen again?A snow covered farm field near Hampshire, Ill., is the epicenter of Wednesday's earthquake. While the bulls sensed the quake was coming, the barn is still standing. There was no damage reported, yet, the 3.8 earthquake was felt over a wide area, which is common for quakes in the Midwest.

"Because we are in a stable earthquake area we don't get too many earthquakes but when we get waves felt at greater distances," Dr. Emile Okal said. The Northwestern geology professor said in the past 100 years there have been eight earthquakes in northern Illinois similar to the one that hit on January 10th.

Dr. Okal said the quake is not related to the New Madrid seismic zone in southern Illinois or the fault line that runs through Sandwich, Illinois.

"We think this is related to another fault which is not well mapped. The reason it is not well mapped out is there are very few earthquakes- once every 10 years or so- in this system," said Dr. Okal.

Dr. Okal said it is highly unlikely Chicago will get hit with the big one. The earthquake in Haiti was 1600 times the magnitude of this morning's earthquake. Regardless, structural engineers say Illinois must be prepared.

"An earthquake in the range of 6 on the Richter scale would do a lot of damage around here," said Gene Corely, engineer.

Corely said Chicago's old infrastructure would not be able to handle a big quake. Corely says older, brick, four-story apartment buildings are especially vulnerable. On the other hand, wooden homes would do well.

"The most important thing is our new buildings be built to the earthquake standards that they should be," said Corely.

Corely said there is no need to reinforce every old brick building. However, if one is being redone, it would be a good idea to strengthen it.

Even for a small earthquake, Corely said to make sure your water heater is well braced to the ground. If it is not and the water heater is connected to a gas line, a small movement can knock the line.


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