At the end of last month, a minor earthquake rattled southeast Ohio鈥檚 Noble County.
A few days later residents reported another. Then another.
By May 8, the Ohio Department of Natural Resources had detected in the county, prompting the agency to halt hydraulic fracturing 鈥� or fracking 鈥� at a well pad there.
鈥淭his part of the continent doesn't have a plate boundary now, but it did in the past,鈥� said Mike Brudzinski, a professor of seismology with Miami University. 鈥淭hat's part of why you see fossils in this area that are from the seafloor. There's no sea here now, but there was at some point in the past.鈥�
Fracking, he said, can disturb those long dormant faults.
How does fracking cause earthquakes?
The process of fracking involves injecting large volumes of fluid into the earth, which cracks open rocks and allows oil and gas to escape.
鈥淭he process is impressive in terms of how much more oil and gas can be harvested per well than it used to be,鈥� Brudzinski said.
But sometimes, the injected fluids leak into deep, dormant faults.
鈥淲e do have cases where human activities can result in earthquakes that could really hurt people. Regulations in Ohio are designed to try and prevent those earthquakes from happening."Mike Brudzinski
鈥淭hose are cases where we can prop open the faults a little bit, and that can allow them to slip and cause earthquakes,鈥� he said.
In the case of Noble County, most of the recent earthquakes were small enough not to be felt by people who live there. But a few crossed that threshold: The strongest quake on April 24 was a