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 Quakes have typically been infrequent in Oklahoma, yet not unheard
of. But in the past year, minor tremors have hit the state hundreds
of times, raising worries the big one may be just around the corner.
"The rate of earthquakes in Oklahoma has increased by about 50
percent since October 2013, significantly increasing the chance for
a damaging quake in central Oklahoma," the U.S. Geological Survey (USGS)
said earlier this week.
Geologists also say that fracking - a controversial technique for
extracting natural gas and oil from underground rock deposits -
could be one of the causes.
Oklahoma City resident Mark Myers said that after the USGS issued
their warning, he called his insurance agent to look into coverage.
"When you see a warning for a major earthquake in Oklahoma, which I
understand is pretty rare, it makes you aware of what could happen,"
Myers said just after speaking to an agent.
Tornadoes have been a persistent concern for Oklahomans, with an
average of 50 hitting a year, usually during the March to August
season, causing billions of dollars in damage.
But there has also been a lot of shaking, with 183 earthquakes of
magnitude 3.0 or greater on the Richter scale occurring in Oklahoma
from October 2013 through April 14, the USGS said.
Oklahoma Insurance Commission spokeswoman Kelly Collins said the
agency was curious to see if there has been a jump in coverage for
earthquakes and did an informal survey.
Three of the top 10 firms in the state responded and said Oklahomans
are taking the threat seriously. When the state had a quake with a
magnitude of 5.6 in 2011, only about 2 percent to 4 percent of
customers had full coverage.
"Now, 12 to 18 percent have that insurance. It's still less than 20
percent of homeowners, but I think this latest warning would catch
people's attention," Collins said.
One factor that may be contributing to the quakes appears to be the
hydraulic fracturing, or fracking, an energy extraction method that
has boosted employment and provided revenue for the financially
strapped state.
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Water injection used in fracking to break up underground, porous
rock formations can increase underground pressures, lubricate faults
and cause earthquakes – a process known as injection-induced
seismicity, the USGS said in a joint statement with the Oklahoma
Geological Survey.
"The recent earthquake rate changes (in Oklahoma) are not due to
typical, random fluctuations in natural seismicity rates," they
said.
Several energy firms have dismissed the link between fracking and
the recent quakes.
There have been two earthquakes that have registered a magnitude of
over 5 on the Richter scale in the state since the 1950s. A 1952
quake with a 5.5 magnitude toppled chimneys in Oklahoma City and
left a 15 meter crack in the capitol building.
The worries are a stronger quake than that could cause even more
damage where many structures are built to withstand tornado winds
but do not have specialized protection against strong seismic
activity.
Dave Herbert of Midwest City said as long as there is fracking, he
will be worried about a damaging quake.
"I took out an insurance policy on my house," said Herbert. "It was
clear to me that Oklahoma was not going to take any meaningful
action. Too many oil big shots in the state."
(Writing by Jon Herskovitz, editing by G Crosse)
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