11:00 AM EDT, July 21, 2012
The conclusions of geological experts on the relationship between fracking and earthquakes are much clearer than letter writer Barbara McNamara suggests ("Fracking is neither safe nor harmless to the environment," July 16).
The National Research Council's report unequivocally states that "the process of hydraulic fracturing a well as presently implemented for shale gas recovery does not pose a high risk for inducing felt seismic events." The 50 earthquakes Mr. McNamara referred to were related to injection wells triggered only small tremors and that continue to be evaluated by federal and state geologists.
Bill Ellsworth, lead author of a study by theU.S. Geological Survey, has said on the record that he is confident that hydraulic fracturing — a process in use since 1947 — is not responsible for earthquake trends that his team has observed.
Geologists and industry regulators across the nation have been quick to dispel rumors of a causal relationship between fracking and earthquakes. Oklahoma state geologist G. Randy Keller called the claims "a rush to judgment," while Interior Department Deputy Secretary David Hayes said his teams have found "no evidence to suggest that hydraulic fracturing itself" is the cause of earthquakes.
According to the USGS, very little is known about the causes of earthquakes in the eastern United States. The first earthquake on record to have its epicenter in Maryland occurred in 1758 — well before hydraulic fracturing technology was invented.
Debbie Brushe, Catonsville
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