Geologic study leaves little room for doubt
By Summit Voice
FRISCO — Youngstown, Ohio, seemingly on stable ground, had never experienced an earthquate going all the way back to 1776. But that all changed in December 2010, when a newly built well started to pump fracking wastewater into the ground.
Starting in January 2011, seismic instruments recorded 109 tremors, and a careful study of the pattern of earthquakes — as strong as a magnitude 3.9 — suggests they are linked to the well in neighboring Pennsylvania.
In a study published in Geophysical Research-Solid Earth, researchers said the onset, cessation, and even temporary dips in activity were all tied to the activity at the Northstar 1 well. The first earthquake recorded in the city occurred 13 days after pumping began, and the tremors ceased shortly after the Ohio Department of Natural Resources shut down the well in December 2011.
“In recent years, waste fluid generated during the shale gas production — hydraulic fracturing, had been increasing steadily in United States. Earthquakes were triggered by these waste fluid injection at a deep well in Youngstown, Ohio during Jan. 2011 – Feb. 2012,” the authors wrote.
Dips in earthquake activity correlated with Memorial Day, the Fourth of July, Labor Day, and Thanksgiving, as well as other periods when the injection at the well was temporarily stopped.
“The earthquakes were centered in subsurface faults near the injection well. These shocks were likely due to the increase in pressure from the deep waste water injection which caused the existing fault to slip,” said lead author Dr. Won-Young Kim.
“Throughout 2011, the earthquakes migrated from east to west down the length of the fault away from the well — indicative of the earthquakes being caused by expanding pressure front,” he concluded.