Researchers at the University of Calgary have made a monumental discovery in the ongoing effort to understand how hydraulic fracturing contributes to earthquakes and potentially forecast seismic events.
According to the team of seismologists, the injection of fracturing fluids can lead to a slow slip on a fault and, over time, the strain the slow slip produces on other sections along the fault can result in a sudden slip and an earthquake. The researchers were able to image fault locations for the study after being provided with access to 3-D seismic data by Calgary-based TGS Canada Cop.
"Based on our model, the earthquake initiates on a part of the fault where friction conditions are unstable," explained Dr. Thomas Eyre, PhD, a post-doctoral researcher in the U of C's Department of Geoscience in a statement released Wednesday. "In the case we studied, the earthquake occurred hundreds of metres above the hydraulic fracturing zone."
Previous laboratory measurements suggested earthquakes should not be possible given the type of rock stimulated by hydraulic fracturing but the U of C research appears to invalidate those claims.
The U of C study indicates increased fluid pressure is the main triggering mechanism of fluids injection-induced earthquakes by either reducing the frictional resistance of the fault or altering the fault loading conditions.
"Our model predicts that slow slip initiates significantly before an induced seismic event," said Eyre. "This could lead to new ways to monitor and forecast felt seismic events."
