OKLAHOMA CITY — A 4.3 magnitude earthquake rattled Alfalfa County in northern Oklahoma Thursday, damaging the county courthouse but causing no injuries.
It was one of several earthquakes, ranging in magnitude from 2.9 to 3.8, that the U.S. Geological Survey said have been recorded in Alfalfa County since about 10 p.m. Wednesday.
"It jolted us pretty good," court clerk Lori Irwin said of the temblor that was recorded at 9:08 a.m. by the U.S. Geological Survey. "Everybody was just shaken."
Damage to the nearly 100-year-old courthouse, built in the early 1920s, was minimal, and employees continued working in the building, Irwin said.
"We just have extra cracks that we didn't have before, some of the older cracks are a little bigger," said Irwin, who was on the third floor of the three-story courthouse when the earthquake happened.
The temblor occurred just days after SandRidge Energy injection well in the same area was shut down because of a 4.1 magnitude earthquake about 7 miles east of Thursday's quake.
Oklahoma Corporation Commission spokesman Matt Skinner said SandRidge's permit for the well required that it be shut down because of the seismic activity. The well is being used to dispose of wastewater related to oil drilling.
"The thing we're most interested in is if we can see, or a researcher can see, a statistical probability of a correlation" between the earthquake and the use of the disposal wells, Skinner said.
Oklahoma Geological Survey research seismologist Austin Holland said disposal wells are a primary focus on the potential cause of the earthquakes.
"It's one of the first places we look," Holland said. "There's plenty of oil and gas activity (in the area) and I'm not sure what's going on. It's a little too early to talk about what was the cause."