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.
Decades have passed with little seismic activity in this region, but 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.
Oklahoma has long been known as potential earthquake country, but "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 phenomena. One theory is that the shaking could be related to wastewater disposal from oil and gas drilling operations that rely on hydraulic fracturing, or "fracking."
Some researchers and environmental groups have long suspected fracking can have seismic repercussions because it forces millions of gallons of water, sand and other materials deep underground to free pockets of fossil fuels.
The energy industry has repeatedly insisted that the practice is safe. Scientists researching the theory say it's not clear yet whether fracking can trigger significant quakes.
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."
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15. 1992 Cape Mendocino Earthquakes: Magnitude 6.5 - 7.2
A series of three earthquakes <a href="http://earthquake.usgs.gov/earthquakes/states/events/1992_04_25_26.php">struck the Cape Mendocino region</a> on April 25-26, 1992 starting with a magnitude 7.2 quake and two strong aftershocks that registered at magnitude 6.5 and 6.7. The initial quake caused a 3-foot tsunami that hit Crescent City. Nearly 100 people were injured in the first shock which hit just below Humboldt County, but significant damage was sustained after a second and then a third quake hit the same area and already weakened infrastructure. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
14. 1971 San Fernando Earthquake: Magnitude 6.6
This earthquake caused tremors that <a href="http://earthquake.usgs.gov/earthquakes/states/events/1971_02_09.php">lasted for more than a minute</a> and caused widespread damage and casualties. San Fernando and the city of Sylmar were the worst hit and sustained $505 million in damage and 65 people were killed. The most significant destruction caused by the quake was the collapse of two hospitals. The newly-constructed Olive View Hospital was pulled more than a foot off its foundation. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
13. 1994 Northridge Earthquake: Magnitude 6.7
The 1994 natural disaster in the Northridge neighborhood of Los Angeles was the costliest earthquake to strike the U.S. NOAA has reported that the <a href="http://www.nws.noaa.gov/om/all-haz/all-haz4.htm">quake caused $42 billion in damage</a> in today’s currency, killed 57 people, and injured more than 7,000. There were severe effects felt throughout the San Fernando valley and tremors caused damage 85 miles from the epicenter of the quake. The event led to an overhaul in insurance policy in California and earthquake coverage was taken out of many plans after insurance companies suffered massive financial losses, <a href="http://earthquake.usgs.gov/earthquakes/states/events/1994_01_17.php">according to the USGS</a>.
12. 2001 Nisqually Earthquake: Magnitude 6.8
The 2001 earthquake originated deep beneath the Earth’s surface as one tectonic plate slipped beneath another within the Cascadia Subduction Zone, <a href="http://articles.cnn.com/2001-03-01/tech/intraslab_1_subduction-quakes-miles-underground?_s=PM:TECH">according to CNN</a>. It created <a href="http://www.dnr.wa.gov/ResearchScience/Topics/GeologicHazardsMapping/Pages/nisqually_eq.aspx">powerful 6.8 magnitude tremors</a> centered in the Puget Sound that seriously damaged the air-traffic control tower at Sea-Tac Airport and almost led to the collapse of the Alaskan Way Viaduct, the Department of Natural Resources reported. There were no direct casualties, but 400 people were injured.
11. 1925 Santa Barbara Earthquake: Magnitude 6.8
This highly destructive earthquake destroyed almost all of Santa Barbara’s historic center and killed 13 people. Tremors lasted for 15 seconds, but aftershocks were felt for an entire month after the quake. One of the most notable events was <a href="http://earthquake.usgs.gov/earthquakes/states/events/1925_06_29.php">the destruction of the Sheffield Dam</a>, the only dam to ever fail during an earthquake. The soil beneath the earthen dam liquified during the tremors and the structure burst, sending a 30 million-gallon wall of water through Santa Barbara, covering most of the city with two feet of mud and debris before draining into the ocean. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
10. 1989 Loma Prieta Earthquake: Magnitude 6.9
The “World Series Earthquake” hit the San Francisco Bay Area during warm-ups for the<a href="http://earthquake.usgs.gov/regional/nca/1989/"> third game of the 1989 World Series </a>between the San Francisco Giants and the Oakland Athletics. It was a short-lived quake, only lasting 10-15 seconds, but 63 people were killed and nearly 4,000 were injured. There was widespread damage throughout San Francisco and Oakland to the tune of several billion dollars. Because of the World Series game, the Loma Prieta quake was the first major earthquake with tremors broadcast on television. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
9. 1940 El Centro Earthquake: Magnitude 6.9
Also known as the Imperial Earthquake, this powerful event was directly responsible for eight fatalities. Railroad tracks that crossed the Imperial fault line were destroyed and a<a href="http://www.data.scec.org/significant/imperial1940.html"> large swath of irrigation systems were destroyed</a> including collapsed water tanks, according to the Southern California Earthquake Data Center.
8. 1999 Hector Mine Earthquake: Magnitude 7.1
The Hector Mine quake hit at 2:45 a.m. in the middle of the Mojave Desert in Southern California. It awoke residents in Los Angeles and Las Vegas, but it’s <a href="http://www.data.scec.org/significant/hectormine1999.html">remote location caused relatively little damage</a> for such a strong event, according to the Southern California Earthquake Data Center. The one casualty of the quake was an Amtrak train that was traveling in the area when tremors struck. The train derailed but sustained only minor, repairable damage.
7. 1949 Olympia Earthquake: Magnitude 7.1
The <a href="http://earthquake.usgs.gov/earthquakes/states/events/1949_04_13.php">largest quake ever recorded in the Puget Sound</a> region, the magnitude 7.1 quake was felt throughout Washington, Oregon and British Columbia and caused $25 million in damage (in 1949 dollars) and 8 casualties. <a href="http://www.pioneersquare.org/">Seattle’s Pioneer Square district</a> sustained some of the heaviest damage resulting in several condemned buildings and more than a hundred burst gas lines. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
6. 1915 Pleasant Valley Earthquake: Magnitude 7.3
This quake is the strongest ever recorded in Nevada, but occurred in <a href="http://earthquake.usgs.gov/earthquakes/states/events/1915_10_03.php">an uninhabited part of the state </a>with minimal damage and no loss of life. Tremors were contained within 50 miles of the epicenter in north-central Nevada. Several strong aftershocks destroyed two adobe houses, collapsed mine tunnels and changed small waterways in the area. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
5. 1992 Landers Earthquake: Magnitude 7.3
The Landers Earthquake hit Southern California <a href="http://earthquake.usgs.gov/earthquakes/states/events/1992_06_28.php">at 4:57 a.m. for two to three minutes</a>, killing three (two of whom had heart attacks) and injuring more than 400 people. It was the most powerful quake in the state in 40 years, but an epicenter in an uninhabited area in the Mojave Desert minimized damage and loss of life. The quake led to a 6.5 magnitude aftershock hit Big Bear City, 22 miles west of Landers, three hours later. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
4. 1983 Borah Peak Earthquake: Magnitude 7.3
The Borah Peak quake was the largest ever recorded in Idaho, and the most expensive, causing $12.5 million (in 1983 dollars) in damage. <a href="http://earthquake.usgs.gov/earthquakes/states/events/1983_10_28.php">Two children were killed by falling masonry</a> while walking to school in the town of Challis, Idaho. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
3. 1959 Yellowstone Earthquake: Magnitude 7.3 - 7.5
This 1959 quake, also known as the Hebgen Lake earthquake, was the largest ever recorded in Montana and <a href="http://earthquake.usgs.gov/earthquakes/states/events/1959_08_18.php">led to drastic geological changes in the area.</a> Magnitude 7.3 tremors caused a massive landslide that moved around 80 million tons of earth, which covered a campground and killed 28 campers before blocking the flow of the Madison River. The natural dam led to the creation of a lake 190 feet deep and six miles long,<a href="http://www.fs.usda.gov/detail/gallatin/specialplaces/?cid=stelprdb5127785"> now called Quake Lake</a>. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
2. 1952 Kern County Earthquake: Magnitude 7.3
The Kern County quake was the largest ever recorded in Southern California in the 20th century. Tremors were felt as far away as Los Angeles where six people were killed, about 100 miles south of the epicenter. There was more than $60 million in damage (in 1952 dollars) and a total of 12 people were killed. The magnitude 7.3 quake was so powerful it shortened the distance between the entrances of two tunnels by 8 feet, <a href="http://earthquake.usgs.gov/earthquakes/states/events/1952_07_21.php">bending train rails into s-shaped curves</a>. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>
1. 1906 San Francisco Earthquake: Magnitude 7.8
The earthquake that hit San Francisco on April 18, 1906 was the <a href="http://earthquake.usgs.gov/earthquakes/states/events/1906_04_18.php">deadliest in U.S history</a>, causing more than 3,000 deaths and $6 billion in damage in today's currency. Magnitude 7.8 tremors shook the city for a full minute and were felt in Oregon and Nevada, more than 350 miles away. The quake is considered one of the worst in California history and was caused by a nearly 300-mile-long rupture in the San Andreas fault with an epicenter close to San Francisco. <a href="http://earthquake.usgs.gov/regional/nca/1906/18april/index.php">Fires also started throughout the city</a> and lasted for days. However, the disaster led to a groundbreaking scientific study that first correlated quake intensity with geographical location (<a href="http://earthquake.usgs.gov/regional/nca/1906/18april/references.php#lawson">called the Lawson Report</a>) and led to the creation of the country’s first agency tasked with studying earthquakes. <em>Information courtesy of the <a href="http://www.usgs.gov/">U.S. Geological Survey</a></em>