Quake of Magnitude 3.5 Rattles Central Oklahoma

The latest earthquake in a string of small temblors that have shaken the Oklahoma City metropolitan area this year struck the morning of Dec. 7, authorities said.

No injuries or property damage were reported when a quake of magnitude 3.5 struck about 11:45 a.m. approximately two miles southeast of Jones, which is about 16 miles east of Oklahoma City.

The Oklahoma County Sheriff’s office received 911 calls from Nicoma Park, Harrah and Choctaw. Residents in Midwest City and Spencer also reported feeling the quake.

Kenneth Luza, an engineering geologist for the Oklahoma Geological Survey, said experts aren’t sure why there have been so many earthquakes in the Oklahoma City area this year. At least half a dozen have been reported since January.

“If there is a fault in that area, it is deep in the subsurface and we’re not aware of it,” Luza said. “Oklahoma literally has thousands and thousands of faults and most don’t have names.”

Oklahoma’s three known fault zones lie roughly between Norman and Pauls Valley; in the Canadian County area; and in the Arkoma basin region in southeastern Oklahoma. The first zone is located in the south metro and the second is west of Oklahoma City.

The state averages about 52 earthquakes annually, with one or two typically felt by humans, Luza said. Earthquakes of magnitude 2.5 to 3 are generally the smallest people can feel.

Thirty-six quakes have been reported so far in 2009, and all of those have been detected.

“One of the reasons we’ve had so many felt earthquakes this year is because of where they’re located,” he said. “They’ve been in much more densely populated areas, so there are more opportunities for them to be felt.”

The largest recorded earthquake in Oklahoma this year was in the Jones area, a 3.7 magnitude quake on Aug. 28 – the same day a 3.4 quake was reported near Ada in southeast Oklahoma.

The largest earthquake ever reported in Oklahoma took place in El Reno in 1952, when a magnitude 5.5 quake toppled chimneys, cracked foundations, loosened bricks and broke windows and dishes, according to a report from the U.S. Geological Survey.

“It just happens that way,” Luza said. “We can go years and years, and sometimes decades, without an earthquake, then we get hit with dozens of them.”