PRAGUE, Okla. (AP) — It's become a predictable routine at Matt Pryor's insurance agency: An earthquake rumbles through Oklahoma, rattling dishes and nerves. Then the phones light up with calls and text messages from desperate residents asking if it's too late to buy a policy to cover any damage.
Business at Pryor's Oklahoma City office has been brisk following a pair of temblors that struck recently near the city of Edmond, a bedroom community where residents are more accustomed to watching the sky for tornadoes than bracing for the earth to move.
Oklahoma is crisscrossed with fault lines that generate frequent small earthquakes, most too weak to be felt. But after decades of limited seismic activity in this region, earthquakes have become more common in the last several years. And a new study by the U.S. Geological Survey suggests they are here to stay.
"The increased hazard has important implications for residents and businesses in the area," cautioned the report, released in October.
Pryor has witnessed the rapid change in thinking.
"It used to be, 'Do I need earthquake coverage?' Now it's changed to, 'How much insurance do I need?'" Pryor said. "I never thought it would be a concern, but anything can happen here."
From 1975 to 2008, only a handful of magnitude-3.0 earthquakes or greater occurred yearly in Oklahoma. But the average grew to around 40 annual earthquakes from 2009 to 2013, seismologists said in the report on the uptick of quake activity.
Since 2009, more than 200 magnitude-3.0 or greater earthquakes have hit the state's midsection, according to the Geological Survey. Many have been centered near Oklahoma City, the most populous part of the state.
Scientists are not sure why seismic activity has spiked, but they are studying the phenomenon. One theory is that the shaking could be related to wastewater from oil and gas drilling that is often discarded by injecting it deep into underground wells.
Research at various drilling sites around the country has shown that wastewater injections can weaken nearby fault lines and produce quakes big enough to be felt.
Drilling systems that rely on hydraulic fracturing, or "fracking," can also trigger quakes, but they are typically smaller than magnitude-2.
Fracking forces millions of gallons of water, sand and other materials underground to free pockets of fossil fuels. The energy industry has repeatedly insisted that the practice is safe.
Oklahoma's strongest recorded earthquake was a 5.6-magnitude surprise that struck in November 2011 near the town of Prague. It damaged 200 buildings, shook a football stadium and rattled parts of seven states.
No one has been killed or seriously injured in the recent quakes, and property damage has been minimal. But the frequent tremors have been enough to weaken the constitution of even the most weather-hardened Oklahomans.
The Geological Survey report stirred up so much concern that the Oklahoma insurance commissioner urged residents to buy earthquake policies, and emergency management officials have reviewed earthquake-safety manuals used in California.
When the quakes happen, the movement feels like somebody's running through Bert Bennett's house, "shaking all the furniture." The vibrating cracks Joe and Mary Reneau's brick chimney and pulls their kitchen cabinets away from the wall. Mark Treat's dishes, drawers and bed start to rattle, and the floor feels like it's "coming alive."
Then there's the sound. Pam Ousley compares it to a sonic boom or some kind of explosion. Bill Hediger says the din is like a "jet engine that rumbles."
"It's kind of scary and you just hope it quits," said Hediger, whose current earthquake-safety plan entails bolting from his Edmond home and running out into the street. "Makes you wonder if I should move away."
Preparing for the worst, officials here are adopting some of the same advice given to residents of the earthquake-prone West Coast, where terms like fault lines and plate tectonics are part of the everyday vocabulary.
Oklahoma officials are recommending a website designed for California residents that offers tips on earthquake preparedness, like anchoring bookshelves to walls and stringing wire across the books to prevent them from toppling onto anyone.
The site, www.earthquakecountry.info, is now being consulted in mid-America, said Austin Holland, a seismologist with the Oklahoma Geological Survey.
"The main thing is securing things that can fall and hurt you," Holland said. "Everybody thinks of the catastrophic failure of buildings when they think of earthquakes, but the most common sources of injuries are falling bookcases, pictures, heavy stuff above your bed."
Some skeptics brush off the fear surrounding the quakes, saying it's all happened before.
In the faded gold-mining town of Meers — an area with a fault line that was once so seismically active that scientists in the mid-1980s installed a seismograph in the local burger joint — Joe Maranto chuckles at all the fuss.
Maranto, who runs a store and restaurant, said a magnitude-7 earthquake that happened around 2,000 years ago caused the Meers Fault to break open above the ground.
"There's nothing new about earthquakes," he laughed. "They've always been here and they always will be here."