Eastern Ohio rattled by 4.0-magnitude earthquake

Eastern Ohio rattled by 4.0-magnitude earthquake

By the CNN Wire Staff
updated 6:40 PM EST, Sat December 31, 2011

(CNN) -- A 4.0-magnitude earthquake struck eastern Ohio on Saturday, a week after a similar but smaller tremor rattled the region, the U.S. Geological Survey reported.

The quake was centered 5 miles northwest of Youngstown and 6 miles southeast of Warren, the agency said. The quake's epicenter was 55 miles east-southeast of Cleveland, and 145 miles northeast of Columbus.

According to the preliminary estimate, the earthquake struck 1.4 miles deep.

Youngstown police Sgt. Michael Kawa said that the "tremor shook the whole building we were in," but that there were no early signs of major damage. That appeared to hold true elsewhere in the eastern Ohio city, based on early post-quake surveys.

"A lot of house alarms, it shook the buildings," Kawa said. "The fire department hasn't reported any major damage."

Within just over three hours of the quake, nearly 4,000 people from 357 zip codes and 23 cities -- including one as far as Salem, Massachusetts, 515 miles from the epicenter -- had submitted reports to the U.S. Geological Survey's "Did you feel it?" form on its website.

There have been "moderately frequent" reports of earthquakes in northern Ohio since the first one was reported in 1823, the federal agency noted. A 1986 tremor, measuring magnitude 4.8, caused some damage. Another in 1998 measured a 4.5 and was centered in northwestern Pennsylvania.

According to the Ohio Seismic Network, a 2.7-magnitude earthquake struck around Youngstown around 1:24 a.m. on December 24.

"No damage was reported," the network said on its website.

On Friday -- one day before the latest, stronger quake -- Ohio Department of Natural Resources Director James Zehringer announced that work would be halted on a fluid-injection well in Youngstown. According to the U.S. Environmental Protection Agency, an injection well "is a device that places fluid deep underground into porous rock formations, such as sandstone or limestone, or into or below the shallow soil layer."

Zehringer's decision came after the state of Ohio invited experts from Columbia University to collect more information about seismic activity in the area. The well is owned and permitted to Northstar Disposal Services, a Youngstown company, according to the state.

"The area surrounding the well has experienced a series of low-level seismic events over the past eight months," the department said in a press release. "While conclusive evidence cannot link the seismic activity to the well, Zehringer has adopted an approach requiring prudence and caution regarding the site."

Prior to Saturday's quake, the state of Ohio had documented 10 "seismic events" in 2011 -- each of them, at that point, of magnitude 2.7 or lower. The Department of Natural Resources Director noted that a 4.0 magnitude quake, like the most recent one, releases approximately 40 times more energy than a 2.7 magnitude tremor.

Ohio is far from the Earth's major tectonic plates, with the nearest ones in the Atlantic Ocean and the Caribbean Sea, the U.S. Geological Survey explains on its website. Still, there are many known faults in this region, with the federal agency noting that it is likely there additional "smaller or deeply buried" ones that haven't been detected.

"Few, if any, earthquakes in the seismic zone can be linked to named faults," according to the geological survey.

http://www.cnn.com/2011/12/31/us/ohi...ake/index.html