American Oil and Gas Reporter - February 2015 - 141

regulatory concerns wherever the northern
long-eared bat occurs."
Despite the white-nose syndrome outbreak, the northern long-eared bat still is
very widely distributed across Northeastern
forests, NAFWA insists. Instead of forcing
states to deal with the regulatory needs of
an endangered listing for the bat, it suggests
conservation efforts should focus on dealing
with the white-nose syndrome's impact.
Unlike many other species considered for
endangered listings, the lack of habitat is
not a problem here, NAFWA holds, making
the potential for species recovery high if
the syndrome can be dealt with.
Threatened Status
In comments submitted in mid-December, the Ohio Oil & Gas Association

urged that if USFWS decided to give the
northern long-eared bat ESA protection,
that it be listed as threatened, not endangered, and allow industry activities under
the 4(d) special rule excepting takes incidental to activities related to development.
OOGA asserts the best scientific and
commercial data available do not support
USFWS's conclusion that the threat of
white-nose syndrome is expected to spread
rangewide in a short time. It says that
conclusion is based on an assumption
that the rate of spread observed in the
Northeast will remain constant throughout
the bat's remaining range, despite evidence
that environmental conditions differ across
the range.
In addition, the association says re-

search on the little brown bat's response
to the syndrome suggests the remnant
populations of other Myotis bat species
may be stabilizing.
White-nose syndrome, not the modification, destruction of curtailment of
northern long-eared bat habitats, is the
immediate and proximate cause of the
bat's decline, the association says. If USFWS decides to list the northern longeared bat, OOGA suggests a threatened
listing should include a rule exempting
takes from certain types of habitat alteration, including normal operations of the
oil and gas industry.
"This is also the only option that
could be used to support white-nose syndrome research and possible cures,"
OOGA adds.
Ì

Induced Or Natural?

Experts Examine Induced Seismicity
By Dan Holder
The National Academies of Science
concluded in 2013 that hydraulic fracturing
does not pose a high risk for inducing
seismic events large enough to be felt by
humans. After reviewing the data, the
U.S. Geological Survey and the U.S. Department of Energy both similarly concluded that fracturing is not a substantial
cause of induced seismicity.
Despite these findings, however, oil
and gas operators accustomed to coping
with technical complexities thousands of
feet below ground continue to contend
with a different kind of challenge: concerns
by some outside the industry that hydraulic
fracturing is associated with increased
seismic activity significant enough to be
detected at the surface.
Seismologist Paul Friberg points out
that an earthquake is simply a fault in
the earth that ruptures. "A seismic event
is anything that causes ground motion. It
may or may not be felt by seismographs
or people," says Friberg, the owner of
Instrumental Software Technologies Inc.
"Good examples of seismic events are
mining blasts or underground nuclear
tests, such as those recorded in North
Korea. In Ohio, there regularly are mine
blasts that sometimes register as large as
magnitude 2.5 earthquakes, but they definitely are not earthquakes."
Scientists continue to debate whether
it is even possible to tell the difference
between a natural earthquake and one
caused by human activities, Friberg reports. One USGS study indicated that
the ground motion induced by man-made

operations often was less than those
caused by normal tectonic plate stressing,
he adds. "The jury still is very much out
on this, as we do not have enough ground
motion data 'close-in' to induced events,"
he says. "The USGS study was based on
felt reports, which are not as accurate as
data collected by sensitive seismographs."
Ernest Majer, a staff scientist and
senior adviser, Earth Sciences Division
at Lawrence Berkeley National Laboratory,
says induced earthquakes have similar
seismic signatures to natural earthquakes.
"Once rocks rub together, they rub
together. Now, there are some subtleties.
How fast the fault slips will modify the
P (primary) and S (shear) waves. Some
people have said they see a higher frequency association with induced earthquakes compared with natural earthquakes.
There is some evidence, but a paper published on that was met with a bit of skepticism," he says.
According to USGS, the number of
all earthquakes recorded, especially in
central and eastern states, has increased
dramatically over the past 35 years. From
1976 to 2000, the figure jumped from a
national average of 21 earthquakes above
magnitude 3.0 recorded each year, to an
average of 100 earthquakes observed annually from 2010 to 2012. Noting concerns
that the increase may coincide with wastewater injection into disposal wells in
states such as Colorado, Oklahoma, Texas,
Arkansas and Ohio, USGS points out
that very few of the more than 30,000
wells used for fluid disposal have been
linked to any kind of seismic activity.
The U.S. Environmental Protection

Agency says there are more than 172,000
Class II wastewater injection wells in
the country, most of which inject into
depleted oil and gas reservoirs in which
the likelihood of inducing earthquakes
large enough to be felt is quite low.
Roughly 40,000 of the wastewater disposal
wells inject brine and other co-produced
fluids from oil and gas operations into
undepleted formations. These injection
operations have a higher-albeit still very
low-probability of inducing earthquakes
large enough to be detected.
Art McGarr, a geophysicist at the
Earthquake Science Center at the U.S.
Geological Survey's Earthquakes Hazard
Program, says research confirms the MidContinent has seen a dramatic jump in
seismic activity. The increase began in
2001 and ramped up significantly in
2008-09.
"It has continued to increase, to the
point that Oklahoma now is seeing more
earthquakes of magnitude 3.0 and greater
than California, even though California
is much larger. Any way you measure it,
it has been a quite remarkable increase
in earthquake activity," he says.
According to a 2014 paper authored
by McGarr, case histories of seismic
events linked to fluid injections reveal
that the maximum magnitude of recorded
earthquakes appears to be controlled by
the total amount of fluids injected, while
the fluid injection rate determines the
frequency of earthquakes. He points out
that even though magnitude 3.0 earthquakes rarely cause any damage, the increased seismicity includes earthquakes
large enough to cause structural damage,
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