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.