Link of earthquakes to fracking suspected

YOUNGSTOWN -- Two minor quakes briefly shook Youngstown on March 17, and since then, seven more -- all too weak to cause damage or even be felt by many people, but strong enough to rattle some nerves -- have struck.

Ohio seismologists who plotted the quakes' epicenters found that most coincided with the location of a 9,000-foot well in an industrial lot along the Mahoning River, just 2 miles from downtown Youngstown.

At the well, a local company has been disposing of brine and other liquids from natural gas wells in Pennsylvania -- millions of gallons of waste from the process called hydraulic fracturing that is used to unlock the gas from shale rock. The location and timing of the quakes led to suspicions that the disposal well was to blame for Youngstown's seismic awakening. As the wastewater was injected into the well under pressure, the thinking went, some of it might have migrated into deeper rock formations, unclamping ancient faults and allowing the rock to slip.

As the United States undergoes a boom in the production of gas from shale, hydraulic fracturing, or fracking, has come under fire from environmentalists and others for its potential to pollute the air and contaminate drinking water.

But the events in Youngstown -- and other, mostly small, tremors in Arkansas, Oklahoma, Texas, British Columbia, and other shale-gas-producing areas -- raise the notion that the technique could lead to a damaging quake.

Scientists say the likelihood of that link is remote. They say thousands of fracking and disposal wells operate nationwide without causing quakes, and the relative shallowness of these wells means that any earthquakes that are triggered would be minor.

Others say that among the thousands of small quakes in Arkansas since last year thought to be tied to disposal wells was one of magnitude 4.7. The largest one near Youngstown was 2.7.

"But an earthquake even of magnitude 4 in a populated area can be an unpleasant thing," said Serge Shapiro, a professor at the Free University of Berlin who has studied what scientists refer to as induced seismicity.

Officials with D&L Energy, the Youngstown firm that has been disposing of the waste, and with the Ohio government say there is no proof of a link.

"Right now we can't definitively say yes or no," said Tom Tugend, deputy chief of the gas and oil division of the Ohio Department of Natural Resources.

Ohio has asked the firm to plug the bottom 250 feet of the well with concrete to ensure that it is sealed from the deeper rock where the earthquakes are thought to have occurred.

Researchers from the Lamont-Doherty Earth Observatory, a part of Columbia University, have installed four temporary seismometers within several miles of the well.