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Chicagoans report swaying buildings

This image of the powerful tremor was taken by a seismograph at Northern Illinois University in DeKalb.
August 24, 2011 4:46:12 AM PDT
Did you feel that? Several Chicagoans called ABC7 Chicago to say they felt the earth move Tuesday afternoon, moments after a 5.8-magnitude earthquake was reported in Virginia.

The quake led to evacuations in Washington, D.C., New York City and other parts of the East Coast. But in downtown Chicago, 750 miles from the epicenter, many people felt the temblor.

"My office is on a corner, of course, I have a window. I started feeling a little dizzy, and I'm like, 'What is this?' And I could see the building moving," Mark Ingram said. "I yelled out, 'This building is moving.' And one of my coworkers yelled out, 'I thought it was just me.'"

Ingram works on the fifth floor of a five-story building at 1111 N. Wells, near Division Street. He said the building swayed for maybe 40-45 seconds.

"This is an earthquake. No storms, the wind is not that high," said Ingram.

"All of a sudden, I started feeling wave after wave on my seat," said Harry Caray's Restaurant owner Grant DePorter, who used to live in California. "I started screaming, 'I think we're having an earthquake,'" he said, although he said that his wife and co-workers, with him on the restaurant's 4th floor, did not immediately believe him.

"We have received reports of people in tall buildings [in Chicago] feeling the East Coast earthquake" said Bob Bauer, engineering geologist with the Illinois State Geological Survey. "Seismic recorders in the Central U.S. show the wave arriving about 2 minutes or so after the East Coast event" Bauer told the ABC7 I-Team. "This is what we expect -- tall buildings far away from an earthquake event feel it."

There are no immediate reports of damage in the Midwest and in many cases "people on lower floors in the same buildings where it was felt did not feel it," Bauer said.

"Everybody was just kinda leaning against their desk and they felt a little woozy," said Brian McPherson, who works in Chicago.

"The earthquake vibrations can be amplified at a higher level," said Phil Carpenter, also a geologist, explaining why people on higher floors may have felt the quake. He sent ABC7 an image from the seismograph at Northern Illinois University in DeKalb, Ill. Carpenter said the seismograph vault is in the basement of Davis Hall, and while humans can't always feel the vibrations, the instrument can.

"The earthquake waves travel through the earth, and they will cause the floor of the basement to vibrate a very tiny amount," Carpenter said.

Due to a difference in soil composition and the earth's crust, ABC7 meteorologist Mike Caplan said, "Earthquakes that happen east of the Rockies are typically felt over a broader geographic area than those west of the Rockies."

The 5.8 earthquake was centered at a shallow depth, Caplan said. He called it a "very significant earthquake, one of the strongest ever recorded in that part of the country."

Seconds later, like the diminishing ripples from a pebble dropped in water, some people in Chicago felt the shaking.

This earthquake originated inside a tectonic plate, not on a fault line, which is one reason why its vibrations radiated much farther.

Waubonsee Community College geologist David Voorhees characterized the earthquake as more fun than destructive, because while it did not cause significant damage, it did get everyone talking.

"Those [plates] are colder and older, so... seismic waves can travel further, so, they would be felt a little bit further," said Voorhees.

Matt Garrison emailed the I-Team from Prentice Hospital in Chicago where his wife is in labor. "She said 'did you feel the building shake'?"

Garrison wrote that two minutes later they "saw report of earthquake on news. Weird (sic) coincidence!"

The East Coast earthquake is unrelated to a 5.3 earthquake in Colorado that happened earlier Tuesday, Caplan said.


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