Oklahoma was hit with 20 small earthquakes on Tuesday, according to the Oklahoma Geological Survey. Five more have occurred today.
“No documented cases of induced seismicity have ever come close to the current earthquake rates or the area over which the earthquakes are occurring,” the OGS said in a recent town hall report, which showed a dramatic increade in Oklahoma earthquakes beginning around 2010.
“Potential cases of induced seismicity have been identified both from hydraulic fracturing and disposal wells,” it said.
The largest quake was a 4.3 magnitude near Guthrie, a town of more than 10,000 residents. But the majority of quakes were so low in magnitude they were imperceptible, ThinkProgress reported.
But this record number of tremors raises the possibility of more damaging earthquakes.
“As a result of the increased number of small and moderate shocks, the likelihood of future, damaging earthquakes has increased for central and north-central Oklahoma,” the US Geological Society and OGS said in a joint statement release in May.
The tremors are something scientitists have never seen before.
“An increase like this has not been observed in modern seismology in an intra-plate setting,” OGS says, noting that the “increase is occurring over a very large area” of more than 25,000 square km.
Fracking requires “wastewater injection” in which water used to extract gas is thrown away by injecting it deep into the ground, possibly changing the stress on fault lines.
“I think ultimately, as fluids propagate and cover a larger space, the likelihood that it could find a larger fault and generate larger seismic events goes up,” said Western University earth sciences professor Gail Atkinson at a Seismological Society of America conference in May.
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