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The US Geological Survey (USGS)
has released a map of earthquakes believed to be the result of human activity.
Experts say most of the quakes were caused by the oil and gas industry
injecting waste-water underground. Fracking was also blamed in some cases.
All
of the areas highlighted on the chart “are located near deep fluid injection
wells or other industrial activities capable of inducing earthquakes,” the
study said.
Such
injection-induced earthquakes are occurring at a rate higher than before,
according to the USGS.
RT.com report continues:
Scientists
said the increase in seismic activity throughout the country is mainly due to
the oil and gas industry injecting waste-water deep underground, which can
activate dormant faults.
Many
of those awakened faults have not moved in millions of years, according to
Geological Survey geophysicist William Ellsworth.
"They're
ancient faults...we don't always know where they are,” Ellsworth said, as
quoted by AP.
A
few cases were blamed on hydraulic fracturing, or fracking – a process in which
large volumes of water, sand, and chemicals are pumped into layers of rock to
free oil or gas.
The
increase in earthquakes has rocked once stable regions in eight states:
Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma, and Texas.
Oklahoma
has been the most affected state recently, experiencing more magnitude-3 and
higher earthquakes in 2014 than California – the most seismically active of the
lower 48 states.
The
Oklahoma Geological Survey stated earlier this week that the rise in quakes in
that state is “very unlikely to represent a naturally occurring process,” since
they are occurring in the same area that saw a huge jump in wastewater disposal
over the past several years, the LA Times reported.
The
state's seismicity rate in 2013 was 70 times greater than the background
seismicity rate prior to 2008, Oklahoma officials said.
Man-made
earthquakes have been a concern for scientists for some time. This is due to
the public risk factor, and the fact that even larger earthquakes could be in store.
“We know, for example, in Oklahoma that there
was an earthquake of about magnitude 7 about 1,300 years ago,” said Ellsworth.
“We have to be guided with what we have seen in the past.”
Still,
the question remains about what should be done to lower the risk of such quakes
occurring.
USGS
geophysicists Art McGarr and Andy Michael have called for better monitoring of
regions with increased seismic activity.
At
present, some areas rely on seismic censors that can't precisely gather the
location of quakes that are smaller than a magnitude-3. But that information
could be immensely helpful to scientists because it would help them locate
areas where seismic pressure is building up and aid them in determining the
size of unmapped faults in those regions.
“It’s
a bit frustrating when we don’t have really good earthquake locations,” Michael
said.
The
release comes just one day after a study announced a more direct link
between fracking and earthquakes in North Texas.
However, studies by the
USGS “suggest that the actual hydraulic fracturing process is only occasionally
the direct cause of felt earthquakes,” according to the agency's website.
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