LITTLE ROCK — A series of earthquakes that have rattled White, Faulkner and Cleburne counties this month have geologists studying to determine if they are the results of naturalgas drilling in the area or an active seismic fault.
The U.S. Geological Survey has recorded 37 temblors since June 3 near Searcy, Higden, Garner, Damascus, Guy, Quitman and Twin Groves. None caused damage, andmost were so small they weren’t even felt.
The most recent quake, which registered magnitude 2.2, rumbled about 6 miles southwest of Searcy at 5:26 a.m. Tuesday.
Three other tremors shook just west of Searcy on Monday, including one that measured magnitude 3.2.
“We are evaluating the data we’ve collected at these sites,” said David Johnston, a geologist with the U.S. Geological Survey in Little Rock. “We can only speculate about what caused them now.”
He said drilling in the area for natural gas could have caused the series of quakes, or it could be a fault reactivating.
In April, a series of quakes in central and western Arkansas drew the scrutiny of Haydar Al-Shukri, director of the Arkansas Earthquake Center at the University of Arkansas at Little Rock.
Because quakes centered near Greenbrier and Hector occurred infrequently, Al-Shukri believed they were caused by workers drilling for gas.
“If it were a fault zone, we’d see constant activity,” Al-Shukri said in April.
The June earthquakes have all occurred at various depths, meaning there’s not just one fault that is causing them.
“It’s hard to say what is causing them,” Johnston said. “We know it’s not related to the New Madrid Seismic Zone.”
That zone, which cuts from southern Indiana to northeast Arkansas, created several large earthquakes, including a series of them in 1811-12 that registered at least 7.0 in magnitude.
Terry Wickre, who lives on the western edge of Searcy, said he did not feel Monday’s earthquake but has felt others, including one Saturday. A 3.3-magnitude earthquake rumbled through the area that day.
“I sat down to watch television,” Wickre said. “I heard some rumbling. I thought it was thunder, but when I went outside, there were no clouds.”
He said he thought a tree may have toppled onto his house, but when he saw a neighbor looking outside as well, he realized it was an earthquake.
Wickre, who moved to Arkansas from Colorado to retire four years ago, laughed about the recent series of quakes.
“After that first one, I told my wife, ‘Pack your bags. We’re moving,’” he said, joking.
Arkansas, Pages 7 on 06/30/2010