The 4.0 Ohio earthquake this weekend was a reminder that activities related to hydraulic fracturing, or 'fracking,' can cause seismic faults to shift if not carried out carefully.
The link between "fracking"-related activities and earthquakes was thrown into stark relief over the weekend when a magnitude 4.0 quake struck Youngstown, Ohio – typically not a hot bed of noticeable seismic activity. The quake triggered shaking reportedly felt as as far away as Buffalo, N.Y., and Toronto.
The temblor struck Dec. 31 and was the latest and strongest of 11 minor-to-light quakes that have hit the region since March. The epicenters are clustered around a wastewater injection well for a hydraulic fracturing operation.
Understanding the potential effect hydraulic fracturing or related activities could have on local earthquake risks is one question some researchers hope to answer as they try to develop tools for communities.
IN PICTURES: US natural disasters of 2011
Fracking allows energy companies to extract natural gas trapped in shale deposits deep underground. By injecting large quantities of pressurized fluids, drillers can break up the rock, releasing the gas for extraction.
One way to dispose of the waste fluids from the process is to inject them back into porous rock formations deep underground. But if pressurized fluids find their way into faults, the fluids can act like a hydraulic jack, separating locked sections enough to allow them to slip.