State officials now say a series of earthquakes that shook Mahoning County last month likely were caused by fracking, leading them to create the most stringent drilling rules in the nation, requiring seismic monitoring near fault lines and epicenters.

State officials now say a series of earthquakes that shook Mahoning County last month likely were caused by fracking, leading them to create the most stringent drilling rules in the nation, requiring seismic monitoring near fault lines and epicenters.



Yesterday, the Ohio Department of Natural Resources announced the rules, which say that monitors must be placed at new drilling sites within 3 miles of known fault lines or areas that experienced an earthquake greater than magnitude 2.0.



The state will not require monitoring at wells that already have been drilled.



Art McGarr, a U.S. Geological Survey scientist leading a nationwide study on man-made earthquakes, said seismic monitors cost about $20,000 apiece, and that as many as five are needed at each well.



Drilling companies would foot the bill, according to ODNR.



�Caution dictates that we take these new steps to protect human health, safety and the environment,� ODNR Director James Zehringer said in a statement.



Geologists recorded 12 earthquakes last month near a Mahoning County well drilled by Hilcorp Energy, a Texas oil company.



They are among the few earthquakes in the United States linked to fracking, a process in which companies drill vertically, then turn 90 degrees into the rock. Then millions of gallons of water, sand and chemicals are blasted into the shafts to free trapped oil and gas.



Earthquakes have happened at a greater rate across Ohio in recent years than they had for more than a century.



On average, there were two quakes a year in Ohio greater than magnitude 2.0 between 1950 and 2009. But between 2010 and 2014, that average rose to nine, according to a Dispatch analysis of Ohio Department of Natural Resources data. Fracking became more prevalent during the same time period.



Nationwide, an average of 100 magnitude 3.0 or higher temblors occurred each year between 2010 and 2012. The average annual rate from 1967 to 2000 was 21, according to the U.S. Geological Survey.



Yesterday, ODNR officials said if monitors at drilling sites detect even a magnitude 1.0 quake, fracking will immediately stop and an investigation will start. If fracking is blamed, a moratorium would be instituted 3 miles around the epicenter.



Won-Young Kim, a seismologist at Columbia University in New York who monitors earthquakes across the northeastern United States, said the news that Ohio now links fracking and temblors isn�t a surprise.



�It�s a similar situation to the injection wells,� Kim said.



A series of earthquakes in Mahoning County in 2011 was tied to a fracking-waste



injection well near Youngstown. That well was shut down by the state, and a moratorium was put in place in the area.



During the fracking process, fluids bubble back up with the gas. Oil and gas wells also produce salt water contaminated with metals and radioactive materials trapped underground for millions of years. That waste often is injected into deep wells.



Kim published research showing a connection between a Mahoning County injection well and earthquakes in 2011 and 2012.



At the time of the first Youngstown earthquakes, there were 177 active waste-injection wells in the state. Now, there are more than 195, and more are being drilled in eastern Ohio. Some of those wells are monitored for quakes on a case-by-case basis, a department spokeswoman said.



Will Drabold is a fellow in the E.W. Scripps School of Journalism Statehouse News Bureau.



@WillDrabold