East Coast Tremor Felt in Illinois

Brenda Mulhern was sitting in her office at 36 E. Grand in Chicago, Tuesday, when she saw a lamp in the corner begin shaking.

"It started making a noise like, tik, tik, tik," Mulhern said. "So I pulled out my iPhone and walked over to make a video."

Moments later, a friend of Mulhern's who lives in Pennsylvania posted on his Facebook page that an earthquake struck the East Coast.

It was actually a 5.8 magnitude earthquake that hit about 90 miles south of Washington D.C. in Virginia. The tremors rocked the East Coast, prompting nuclear reactors to be taken offline in Virginia, national monuments to be evacuated and the Pentagon to go on high alert.

Reports from NBC colleagues in New York City said the headquarters at 30 Rockefeller Center was under alert because the building swayed.

Mulhern believes she felt the same quake all the way in Chicago.

NBC Rockford affiliate WREX reports on Twitter that the Rockford City Hall  was evacuated due to shaking and the Faust Landmark High Rise reported windows rattling.

It wouldn't be the first time an East Coast quake was felt in Illinois. In 1998, a 5.2 magnitude earthquake centered in Greenville-Jamestown Pennsylvania was felt as far away as Illinois, Ontario, Canada and New Jersey.

Northwestern University professor Dr. Van Der Lee said it's quite common for earthquakes in other parts of the country to be felt in the Midwest.

"It's not unheard of," she said. "The seismic waves of these earthquakes can travel very large distances."

Tuesday's quake struck at 12:51 p.m. Central Time.  By the time the shockwaves reached Illinois some two minutes later, they were very minor but still registered on the university's seismometer.

Jerry Gilmer from Sycamore, Illinois said he was sitting in his lounge chair around 1 p.m. when he felt the chari begin to rock back and forth slightly.

"It certainly wasn't rocking a lot and it wasn't dramatic - just slow and gentle, very mild," he said via email.

Tracy Raetzman from Des Plaines told a similar story.

"We felt something again up here on the second floor in Des Plaines. It lasted a little while, maybe close to a minute," she said.

Numerous airports across the East Coast reported ground stops, meaning all flights have been postponed, because of the earthquake. O'Hare Airport, however, has not been affected by those delays.

This is data from a seismometer, located on the campus of Northwestern in Evanston.  All recordings are based on Greenwich Mean Time.  The quake happened at 17:51 Greenwich Mean Time or 1:51 Eastern (12:51) Central.  Looking at this graphic, you’ll notice spikes starting to register on the Northwestern seismometer at 17:53:30 (12:53:30).   (Keep in mind it takes time for the seismic waves to travel from Virginia to Chicago)