and North Atlantic and indicate the potential for
amplification of decadal-scale variability through
interbasin resonance (42, 43). Before the 1970s,
variability in poleward heat fluxes and storm tracks
in the North Pacific and North Atlantic regions
were uncorrelated; more recently, highly correlated
behavior has emerged (44). Our study documents
that the development of such teleconnected variability between these regions is a fundamentally
important phenomenon associated with rapid
warming, suggesting that such properties may be
high-priority targets for detailed monitoring in
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We thank B. Jensen and D. Froese for the tephra analyses;
J. Southon for assistance with radiocarbon samples; A. Ross,
J. Padman, and J. McKay of the College of Earth, Ocean and
Atmospheric Sciences Stable Isotope Lab; and five anonymous
reviewers. This work was supported by NSF grants AGS-0602395
(Project PALEOVAR) and OCE-1204204 to A.C.M., and an NSF
graduate research fellowship to S.K.P. The data can be found in the
supplementary online materials and at the National Oceanic and
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Materials and Methods
Figs. S1 to S11
Tables S1 and S2
10 February 2014; accepted 24 June 2014
Sharp increase in central Oklahoma
seismicity since 2008 induced by
massive wastewater injection
K. M. Keranen,1 M. Weingarten,2 G. A. Abers,3† B. A. Bekins,4 S. Ge2
Unconventional oil and gas production provides a rapidly growing energy source; however,
high-production states in the United States, such as Oklahoma, face sharply rising
numbers of earthquakes. Subsurface pressure data required to unequivocally link
earthquakes to wastewater injection are rarely accessible. Here we use seismicity and
hydrogeological models to show that fluid migration from high-rate disposal wells in
Oklahoma is potentially responsible for the largest swarm. Earthquake hypocenters occur
within disposal formations and upper basement, between 2- and 5-kilometer depth. The
modeled fluid pressure perturbation propagates throughout the same depth range and
tracks earthquakes to distances of 35 kilometers, with a triggering threshold of ~0.07
megapascals. Although thousands of disposal wells operate aseismically, four of the
highest-rate wells are capable of inducing 20% of 2008 to 2013 central U.S. seismicity.
Seismicity in the United States midcontinent surged beginning in 2008 (1), predominantly within regions of active unconventional hydrocarbon production (2–6). In Arkan- sas, Texas, Ohio, and near Prague, Oklahoma, recent earthquakes have been linked to
wastewater injection (2–7), although alternative interpretations have been proposed (1, 8).
Conclusively distinguishing human-induced earthquakes solely on the basis of seismological data
Seismic swarms within Oklahoma dominate
the recent seismicity in the central and eastern
United States (9), contributing 45% of magnitude
(M) 3 and larger earthquakes between 2008 and
2013 (10). No other state contributed more than
11%. A single swarm, beginning in 2008 near Jones,
Oklahoma, accounts for 20% of seismicity in this
region (10). East of Jones, the damaging 2011 moment magnitude (Mw) 5.7 earthquake near Prague,
Oklahoma, was likely induced by wastewater injection (2, 8, 11, 12), the highest magnitude to
date. These earthquakes are part of a 40-fold increase in seismicity within Oklahoma during 2008
to 2013 as compared to 1976 to 2007 (Fig. 1, inset A)
(10). Wastewater disposal volumes have also increased rapidly, nearly doubling in central Oklahoma
between 2004 and 2008. Many studies of seismicity near disposal wells rely upon statistical relationships between the relative timing of seismicity,
disposal well location, and injected water volume
to evaluate a possible causal relationship (3–7, 13).
Here we focused on the Jones swarm and compared modeled pore pressure from hydrogeological
models to the best-constrained earthquake hypocenters (14). Using data from local U.S. Geological
Survey NetQuake accelerometers, the Earthscope
Transportable Array, and a small local seismic network (fig. S1), we generated a catalog of well-located
earthquakes between 2010 and 2013. Event-station
distances were predominantly less than 10 km
(fig. S2D), and all earthquakes were recorded on
at least one seismometer within 20 km of the initial hypocenter. To study pore pressure changes at
earthquake hypocenters and the apparent migration in seismicity, we developed a three-dimensional
hydrogeological model of pore pressure diffusion
from injection wells.
The Jones swarm began within 20 km of high-rate wastewater disposal wells, among the highest rate in Oklahoma, between two regions of
fluid injection (Fig. 2). The four high-rate wells
are southwest of Jones in southeast Oklahoma
City (SE OKC) and dispose of ~4 million barrels
per month (15) (Fig. 3). The target injection depth
is 2.2 to 3.5 km into the Cambrian-Ordovician
1Department of Earth and Atmospheric Sciences, Cornell
University, Ithaca, NY, USA. 2Department of Geological Sciences,
University of Colorado, Boulder, CO, USA. 3Lamont-Doherty Earth
Observatory of Columbia University, Palisades, NY, USA. 4U.S.
Geological Survey, Menlo Park, CA, USA.
*Corresponding author. E-mail: email@example.com †Present
address: Department of Earth and Atmospheric Sciences, Cornell
University, Ithaca, NY, USA.