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Small earthquake shakes McHenry County

posted Jan 31, 2012, 8:16 PM by Brian Donahoe   [ updated Feb 21, 2012, 2:08 PM ]

A minor earthquake Tuesday night in McHenry County shook some northern suburban residents but did no damage, officials said.

The earthquake happened at 9:54 p.m. about 3.2 miles underground near McHenry, roughly 45 miles northwest of Chicago, according to the U.S. Geological Survey’s National Earthquake Information Center.

The seismic event measured just 2.4 on the Richter scale which qualifies it only as a minor earthquake, said Shengzao Chen, a geophysicist with the U.S. Geological Survey in Golden, Colo.

Officials have received no reports of damage or injuries, Chen said. Residents probably only felt the ground shake for a few seconds.

The last earthquakes in our region happened in 2010, when separate 3.8 and 2.7 magnitude quakes struck on the Illinois side of the border, he said.

Officials earlier Tuesday had initially placed the epicenter just over the Wisconsin border, but new information shows the quake happened on the Illinois side.

Earthquakes are tracked here...

Date-TimeTuesday, January 31, 2012 at 03:54:43 (UTC) - Coordinated Universal Time 
Monday, January 30, 2012 at 09:54:43 PM local time at epicenter 
Time of Earthquake in other Time Zones
Location42.31N 88.21W
Depth5 kilometers
Distances19 km (12 miles) E of Woodstock, Illinois
31 km (19 miles) W of Waukegan, Illinois
70 km (43 miles) NW of Chicago, Illinois
304 km (189 miles) NNE of SPRINGFIELD, Illinois
Location UncertaintyError estimate
ParametersNst=16, Nph=16, Dmin=180.0 km, Rmss=0.62 sec, Erho=12.8 km, Erzz=1.9 km, Gp=80.0 degrees
Event IDus2012wkae

 P-wave travel times (in minutes)