Sharp increase in central Oklahoma seismicity since 2008 induced by massive wastewater injection

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Science  25 Jul 2014:
Vol. 345, Issue 6195, pp. 448-451
DOI: 10.1126/science.1255802

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  1. Fig. 1 Earthquakes in Oklahoma between 1976 and 2014.

    Earthquakes are M > 1 from the NEIC catalog (10). Black lines are faults (2628). Small and large dashed gray boxes outline the areas used for analysis of the Jones swarm and of central Oklahoma, respectively, in inset B. OKC: Oklahoma City. Inset A: Comparison of M3+ earthquake rate in Oklahoma and California, normalized by area. California is ~2.3 times larger than Oklahoma. 2014 earthquakes are through the first 4 months. Inset B: Expanding area of the Jones and the broader central Oklahoma swarms. Regions were divided into 5 km by 5 km grid cells, and any cell with an earthquake was considered part of the swarm. Swarm area per year is inclusive of all prior years.

  2. Fig. 2 Earthquake catalog and swarm migration.

    (A) Jones earthquake catalog March 2010 to March 2013 using local stations. Squares are injection wells operating at an average rate ≥ 400,000 barrels per month (15, 29); triangles are high–water production wells. Background color and contours represent depth to the top of the Hunton Group (15). The Hunton Group is higher in section than the Arbuckle Group but has more data on formation depth. (B) Earthquake depth histogram; earthquakes are dominantly in sediment and upper basement. (C) Distance of each March to October 2010 Jones earthquake to the SE OKC disposal wells. The dense region of the swarm increases in distance between days 150 and 250 in 2010. (D) Map view of Jones earthquakes during March to October 2010, colored by time. Semicircles are equidistant lines from SE OKC disposal wells. Faults at greater distance from the wells become active at later times. Details of two of these fault planes are shown in insets of Fig. 2A and are discussed in the text.

  3. Fig. 3 Fluid injection reported in the four high-rate SE OKC wells.

    (A) Sum and individual monthly injection volumes and (B) wellhead pressure and cumulative, summed injected volume (15). The DT SWD #1, FP SWD #1, and S SWD #1 wells are in close proximity; the C SWD #1 well is ~3.5 km away. Gray shading denotes injection rates for notable past cases of induced seismicity for reference (table S1). Cumulative seismic moment in (B) is calculated from M3+ earthquakes from 2005 to January 2014 (10) for earthquakes within the box outlining the Jones swarm in Fig. 1.

  4. Fig. 4 Hydrogeologic model of pore pressure perturbation from injection wells.

    (A) Modeled pressure perturbation in December 2009 and (B) in December 2012 with a hydraulic diffusivity of 2 m2/s (14). The model includes the four high-rate SE OKC wells and 85 wells northeast of the Jones swarm near the West Carney field. The modeled pressure perturbation is dominated by fluid injected at the high-rate SE OKC wells. Earthquakes are plotted from 2008 to 2009 (A) and 2008 to 2012 (B) (10). (C) Vertical cross section through model results. Pore pressure rises in the Arbuckle Group and uppermost basement. (D) Pore pressure increase at the hypocenter of each earthquake in our local catalog. A pore pressure increase of ~0.07 MPa is the modeled triggering threshold. Modeled pore pressure rises throughout much of the swarm area for hydraulic diffusivity between 1 and 4 m2/s (fig. S7).