The Associated Press reports that “a new study suggests fracking triggered hundreds of small, unnoticeable earthquakes in eastern Ohio late last year, months before the state first linked seismic activity to the much-debated oil-and-gas extraction technique.”  

“The report, which appears in the November issue of the journal Seismological Research Letters, identified nearly 400 tremors on a previously unmapped fault in Harrison County between Oct. 1 and Dec. 13, 2013.”  

“That included 10 quakes of magnitudes of 1.7 to 2.2. That’s intense enough to have temporarily halted activity under Ohio’s new drilling permit rules had they been in place at the time, but is still considered minor.”