By JUDY SHERIDAN
The series of recent earthquakes in northern Parker County could have been a domino effect triggered by a single injection well, according to John Wickham, Ph.D., a professor in the Department of Earth and Environmental Sciences at the University of Texas at Arlington.
“Once the stress is released on one small fault, it moves a bit and pushes the rocks that are on the end of the fault and increases the stress there. That can trigger another earthquake,” he said. “I’m not familiar with the area; I’m just saying what’s possible.”
The earthquakes — seven between Nov. 5 and Nov. 8 — were recorded west of Briar, south and east of Springtown, in the Reno area — with an aftershock in Newark — and near Azle, with magnitudes ranging from 2.4 to 3.0.
While natural causes cannot be ruled out because stress is always building up in the earth’s crust, it is more likely that an injection well — used to dispose of fracking waste — is to blame, Wickham said.
“The research indicates that earthquakes are not caused by fracking,” he said, “but they could be linked to the injection wells that go a lot deeper, 10,000 feet or more.
“It’s well known that when you put fluids under pressure in a rock formation, it can release natural stress buildup.”
It is improbable, but possible, Wickham said, that the small quakes will lead to larger ones.
“Sometimes that does happen,” he said, “but we’re not near the tectonic plate boundaries in Texas. The larger earthquake action takes place along the plate boundaries in California, Japan, the coast of Chile. The largest recorded in Texas is a 5.0. The largest ever recorded is on the order of 9.”
The scale is not linear in terms of the amount of energy released, Wickham said, but logarithmic.