Date: June 28, 2004

Location: Northern Illinois

Magnitude: 4.2

Time: 1:10 am CDT

Posted: June 28, 2004

The ripple effects of a 4.1 magnitude earthquake centered in northern Illinois shook furniture, woke sleeping residents and interrupted a field sobriety test early Monday morning in southeastern Wisconsin.

The earthquake's epicenter was about 8 miles northwest of Ottawa, Ill., near the village of Troy Grove and 70 miles west of Chicago. The epicenter along the Sandwich Fault Zone had a preliminary depth of 3.1 miles. It was not connected with the New Madrid Fault farther south,which has been responsible for the Midwest's most serious earthquakes. Tremors also were felt in Indiana, Iowa, Missouri and southwestern Michigan. No injuries or damage were reported.

But the tremors were enough to startle 18-year-old Nicole Hawkins out of her bed and send her running to her parents' room.

Hawkins, of the 4900 block of N. 89th St., was watching TV when she saw her bed, dresser and walls shake for a few seconds at 1:11 a.m.

"I thought something exploded in the area, then Nicole came in the room and said, 'Mom, Dad, excuse me, did you just feel that? My bedmoved,' " said Nicole's mother, Viola Hawkins.

Police departments in Milwaukee, Mequon, Wauwatosa and River Hills fielded calls from worried residents. Most people, such as Trudy Joers of the Solar Heights subdivision in Mequon, at first dismissed the brief tremor as movement from the wind, or the house settling.

"First it made a noise, not a boom, but like a pop. Then the computer moved - it just shook a little," Joers said.

Police officers conducting a field sobriety test near Port Washington and Mequon roads reported seeing their squad cars shake, said Sgt. Steve Graff of the Mequon Police Department.

Ursula Bork of Greenfield said she knew it was an earthquake right away.

"I woke up because I had to go to the bathroom; all of a sudden my bed started swaying. It was a scary feeling," said Bork, who lives on the third floor of her apartment building near 87th St. and Howard Ave.

Earthquakes are rare in Milwaukee, said University of Wisconsin-Milwaukee seismologist Keith Sverdrup. The most recent quake felt here occurred Sept. 25, 1998, with an epicenter along the Ohio-Pennsylvania border. Another earthquake on June 18, 2002, with an epicenter near Evansville, Ind., was felt as far north as Kenosha.

In the past century, just one earthquake has been centered in the Milwaukee area. That 4.0 magnitude earthquake hit on May 6, 1947, at 3:25 p.m.

On Sept. 14, 1972, there was an earthquake of a similar magnitude and at the same location as the one felt Monday, Sverdrup said.

"It's fair to say that the effect of (Monday's) earthquake would be very similar to the 1972 one. . . . It would be felt indoors by most, and outdoors by a few. It feels like a heavy truck driving by."

Earthquake magnitudes are calculated from ground measure recorded on seismographs. The least severe earthquakes have magnitudes of less than 3.5, while the most destructive earthquakes have magnitudes of greater than 8.

The Associated Press contributed to this report.

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