Page 28 - aruba-today-20161202

A28 SCIENCE
Friday 2 december 2016

After new regulations, Oklahoma’s shakes calm down a bit

SETH BORENSTEIN “Definitely the rate of sense.
AP Science Writer quakes have gone down,” “We’re not out of the
WASHINGTON (AP) — The said USGS geophysicist woods yet. There is still a
rate of earthquakes in Robert Williams. “At the possibility for potentially
Oklahoma has dropped same time we had more damaging earthquakes,”
dramatically since late magnitude 5s this year than Zoback said. “It’s going to
May, when the state lim- ever before historically in take a few years for the sit-
ited wastewater injections Oklahoma. It’s good news uation to return to normal.”
into energy wells, an Asso- on one hand. It’s heading Oklahoma officials said
ciated Press statistical anal- in the right direction, but they plan to continue
ysis shows. And a new sci- troubling to see these large the regulations and are
entific study says the state damaging quakes in Paw- expected to release a
is on its way back to calmer nee and Cushing.” new directive in the next
times that prevailed before Over the last couple years, couple of weeks for the
a huge jump in man-made scientists have linked a dra- 15,000-square-mile area
quakes. matic increase in earth- where strong quakes rat-
For quake-prone parts of quakes in Oklahoma, Kan- tled Pawnee and Cushing.
Oklahoma, the state or- sas and Texas to the prac- “Obviously the goal is
dered what is essentially a tice of injecting wastewa- to bring seismicity down
40 percent reduction in in- ter from hydraulic fractur- to what, for Oklahoma,
jection of the saltwater that ing, or fracking, back un- In this Sept. 12, 2016 photo, Matt Skinner, public information of- would be considered a
ficer at the Oklahoma Corporation Commission, speaks during
scientists generally blame derground after drilling for a news conference on recent earthquake activity, in Oklahoma normal level. That’s the
for the massive increase in oil and gas. Higher volumes City. goal,” said Matt Skinner, a
earthquakes. This year, be- of wastewater injected are Associated Press spokesman for the Okla-
fore the new rules went into connected to more quakes homa Corporation Com-
effect on May 28, Oklaho- with the fluids adding more had an average of less than Oklahoma averaged one mission, the agency that
ma averaged 2.3 quakes pressure to tiny faults. After a quake per day, though magnitude 3.0 earthquake oversees oil and gas op-
a day. Since then the aver- Kansas regulated waste- a 5.0 magnitude quake a year; now it is good news erations. “Things will take
age dropped to 1.3 a day, water volume in March shook the vulnerable Cush- that the rate is down to time, but we’re going to
based on AP’s analysis 2015, a January AP analy- ing area where massive oil one a day, he said. In 2015, move ahead with actions
of U.S. Geological Survey sis showed that Kansas felt reserves are stored. Oklahoma averaged 2.3 that will hopefully make
data of earthquakes of fewer quakes, while less- “The trend is obvious,” said magnitude 3.0 or larger that time sooner rather
magnitude 3.0 or larger. regulated Oklahoma got Stanford University profes- quakes a day. In 2014, it than later.”
But some of those fewer more. In response, Oklaho- sor William Ellsworth. He was 1.6 per day. Oklahoma has had three
post-regulatory quakes ma announced new regu- said the AP numbers were A study published Wednes- quakes magnitude 5.0 or
have been large and dam- lations. similar, but not identical to day in the journal Sci- larger since 2014, and two
aging. This November, Oklahoma a trend he calculated using ence Advances by a dif- of them occurred after the
a different database and ferent Stanford seismolo- May regulations took ef-
different size earthquakes. gist, Mark Zoback, saw the fect: The September 5.8 in
He said the new regulations reduction in Oklahoma Pawnee and the Novem-
were partly responsible for quakes and used intricate ber quake in Cushing.
the falloff in earthquakes, computer simulations to Pent-up pressure may be
but he noted there also has show that the rate of earth- partly to blame, Zoback
been less drilling because quakes will continue to go said. And Williams noted
of a crash in oil prices. down and eventually re- some injecting continues.
Williams of USGS said it is im- turn to near pre-2009 levels. Mainly, though, “we don’t
portant to put even the re- Williams and Ellsworth, who understand the plumb-
duced one-a-day quakes weren’t part of the study, ing down there,” Williams
in context. Before 2009, said Zoback’s work made said.q