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Correlation or Causation? New Research on Fracking Tremors


Another report was leaked this week linking fracking—the drilling technique that has unlocked vast reserves of oil and gas trapped in shale—to earthquakes. The report, released by the same group of scientists who previously linked fracking’s wastewater disposal with micro-quakes, purports to show that the controversial oil and gas extraction process is likely responsible for an uptick in seismic activity via an entirely different mechanism. The WSJ reports:

The new study doesn’t find much evidence that the man-made fracturing is causing earthquakes all by itself.

The connection [between fracking and earthquakes] is more indirect, the study found: New wells are extracting nearly 600,000 barrels of oil a day and a considerable amount of water as well. Given the scale at which oil is now being removed, enough liquids are being disturbed that rocks are settling and faults slipping, causing the small earthquakes.

If the link between fracking and earthquakes turns out to be more than merely correlative, and the drilling process is, in fact, causing tremors, a whole slew of valid questions will arise. The study hasn’t been officially released yet, and until it’s subjected to rigorous peer review, we won’t be able to make too much of it. But it’s a sobering reminder that extracting resources from deep underground isn’t nearly as easy as the Beverly Hillbillies made it out to be.

[Earthquake image courtesy of Shutterstock]

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  • rheddles

    And it only took 40 years to learn of this. You’d think some one would have noticed before now. But greens will grasp at any straw to create FUD.

  • Andrew Allison

    It seems pretty obvious that if large amounts of fluid are removed, the ground will settle. California’s Central Valley, for example, has subsided as much as 28 feet due to extraction of water. Guess we’d better stop growing 25% of the country’s vegetables there! In total, more than 17,000 square miles in 45 States, an area roughly the size of New Hampshire and Vermont combined, have been directly affected by subsidence ( Has there been an increase in seismic activity? Nope.

    • Thirdsyphon

      I’m not a geologist, but I think that fracking operations involve the removal of matter situated between rock layers that are much deeper than the water table. That being the case, the amount of weight on top of those layers, and the consequent release of kinetic energy when they collapse, would be expected to be that much greater.

      • Andrew Allison

        I’m not either, but we’re talking about water extraction which has lowered water tables in CA and AZ 400 feet resulting in feet of subsidence rather than millimeters by frackstraction (just made that up — maybe it too will make it to OED). Wouldn’t the release of kinetic energy be rather gradual in either case?

        • Thirdsyphon

          I like the sound of “frackstraction” quite a lot, although I wouldn’t try saying it too fast in mixed company. . .

          Again, this is still amateur hour at my end (my education in geology concluded around the 9th grade) but from what I can gather, fracking involves the injection of fluid into the space between two long, flat, horizontal rock layers to force them apart and thus create an avenue for the oil and gas trapped between them to escape.

          So far so good; but when this activity happens to overlap with a naturally occurring fault, the fracking fluid can penetrate into the space between the walls of the fault. This has the effect of reducing the friction between the two sides of the fault, potentially to the point where the fault can move. . . and there’s your earthquake. Since fracking fluid gets injected twice (once to create the well and once, after it’s been withdrawn from the extraction site, to dispose of it), there’s some dispute over whether the earthquakes are being mainly caused by the fracking injections or by the disposal injections, but I think both theories share this general outline.

          Again, I’m not suggesting that this effect is the end of the world or anything. . . but I do think it’s probably real, and that as such it’s a risk that will need to be managed.

          • Andrew Allison

            “Given the scale at which oil is now being removed, enough liquids are
            being disturbed that rocks are settling and faults slipping, causing the
            small earthquakes.” is a statement unsupported by any evidence. Wouldn’t the forces of mountain building and plate tectonics have much greater effect? Is it conceivable that, as along the intensively studied San Andreas fault, micro-earthquakes release tension that would otherwise result in a large earthquake? The fact that this paper was leaked before being peer reviewed suggests to me that it’s authors are more concerned with creating FUD than science.

          • Thirdsyphon

            Nobody denies that there are far greater forces at work in the earth’s crust than humanity’s tiny efforts to extract a few crumbs of resources from it.

            At worst, fracking is believed to be responsible for causing some earthquakes that range up to about a 4 on the Richter scale. That’s enough to startle people and to cause some light structural damage, but it’s hardly the stuff of disaster movies. A community could rationally choose to shoulder this risk in exchange for the well-paying jobs and fresh tax revenue that fracking can offer. But a community could also rationally choose not to.

  • Thirdsyphon

    I think it’s pretty clear that fracking is causing these microquakes. The only blank left to fill in is the exact causal mechanism by which it’s doing so.

    This discovery should not and almost certainly won’t mean the end of fracking activity in the kind of sparsely built, lightly populated areas of the country that are currently being developed; but it should and probably will be the end of calls for states and municipalities to be prohibited from tightly regulating fracking if they’re so inclined.

    The tradeoff between access to valuable mineral resources and the risk of infrastructure-damaging microquakes will create different policy incentives in different locales. What makes sense for Williston, ND may very well not make sense for Cleveland, OH or New York, NY.

    • Andrew Allison

      Evidence please.

      • Thirdsyphon
        • Andrew Allison

          Sorry, but, “A recent dramatic increase in seismicity in the midwestern United States MAY be related to increases in deep wastewater injection. Here, we demonstrate that areas with suspected anthropogenic earthquakes are also more susceptible to earthquake-triggering from natural transient
          stresses generated by the seismic waves of large remote arthquakes.
          Enhanced triggering susceptibility suggests the presence of critically
          loaded faults and potentially high fluid pressures. Sensitivity to
          remote triggering is most clearly seen in sites with a long delay
          between the start of injection and the onset of seismicity and in
          regions that went on to host moderate magnitude earthquakes within 6 to 20 months. Triggering in induced seismic zones COULD therefore be an indicator that fluid injection has brought the fault system to a critical state.” is not evidence.
          Furthermore, if fracking is triggering quakes which would otherwise be remotely triggered, where’s the foul? Put differently, the question should be: would these quakes occur anyway?
          Investigation is required, but the hypothesis that fracking causes quakes which would not other wise occur is just that. In addition, the hypothesis that induced micro-quakes reduce the impact of remotely-triggered quakes (making frackquakes a good thing LOL) needs to be considered.
          Please don’t misunderstand me; I want to know if frackstraction causes something that wouldn’t happen otherwise, but this report doesn’t address it, and is psuedo-science at it’s worst. Regards, Andrew

  • stanbrown

    “until it’s subjected to rigorous peer review”

    Why should this study be treated differently than other studies? Peer review is a joke.

  • Jacksonian_Libertarian

    80 million barrels per day of oil, and an unknown amount of water is pumped out of the ground every day worldwide, and it’s been going on for many decades. You would think that if subsidence was causing quakes, it would have been noticed before now. So, I’m going to have to go with irate environmentalists that know they are losing the argument, and are reduced to grasping at straws.

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