How one US state went from two quakes a year to 585

By Juliana Keeping, AFP
September 22, 2015, 12:00 am TWN

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CRESCENT, Oklahoma--The central U.S. state of Oklahoma has gone from registering two earthquakes a year to nearly two a day and scientists point to a controversial culprit: wastewater injection wells used in fracking.

Located in the middle of the country, far from any major fault lines, Oklahoma experienced 585 earthquakes of a magnitude of 3.0 or greater in 2014. That's more than three times as many as the 180 that hit California last year.

"It's completely unprecedented," said George Choy, a seismologist at the U.S. Geological Survey.

As of last month, Oklahoma has already experienced more than 600 quakes strong enough to rattle windows and rock cars. The biggest was a 4.5-magnitude quake that hit the small town of Crescent.

Sandra Voskuhl, 76, grew up in the rural oil boomtown and said she has never felt the earth shake like it did on July 27.

First came a thunderous boom. Then the red earth shook hard, Voskuhl said.

"You heard it coming," she said. "Everything shook."

She recalled screaming as framed pictures toppled over in her home.

Then, when things got quiet, she drove over to the town's Frontier Historical Museum to help clean up antique dishes that had crashed to the ground and shattered.

"We need the oil for our workers and our economy," she said. "But these earthquakes are a little scary."

Could a 'Big One' Hit?

Hydraulic fracturing, or fracking, is the process of shooting water mixed with sand and chemicals deep into the earth to crack rock formations and bring up oil and natural gas trapped inside.

The process has unlocked massive amounts of oil and gas in Oklahoma and other states over the past decade.

But along with the oil and gas comes plenty of that brackish water, which is disposed of by injecting it into separate wells that are dug as deep as just under two kilometers below ground.

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