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I'm currently living in Oklahoma, and there has been an abnormal amount of earthquakes lately, by abnormal I mean more then 5 in a day(not sure if that's normal or not)..

I've also been told that in OK earthquakes are a relatively new thing, now they've brought a bunch of experts in to try to figure out the problem but my question being what could possibly cause so many earthquakes to start happening randomly?

I have a couple theories:

  • Oil wells, we're sucking up all the oil in the ground and the planet is trying to cope with it
  • Underwater waste pipes, idk if these would have anything to do with it, but putting something underground that isn't natural seems like a bad idea to me..

For some insight on what's happening see here see also graph


UPDATE:

There has been 30 earthquakes in the past 21 hours.

30 earthquakes today
76 earthquakes in the past 7 days
196 earthquakes in the past month
2,213 earthquakes in the past year

Taken from Today's Earthquakes


UPDATE 2:

14 earthquakes today
81 earthquakes in the past 7 days
206 earthquakes in the past month
2,222 earthquakes in the past year

September 2016 update

https://www.usgs.gov/news/magnitudes-oklahoma-earthquakes-shift-upward

Does this new development change any of the existing answers?

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  • $\begingroup$ It would be interesting if one of those experts happened to see your question! $\endgroup$ – DoubleDouble Jan 7 '16 at 20:57
  • $\begingroup$ @DoubleDouble Lol, that would be pretty cool. I doubt it will happen but that would be very, very interesting. $\endgroup$ – Bam Jan 7 '16 at 22:29
  • $\begingroup$ Bear in mind that that website will list many earthquakes in most parts of the world, most of which (all the little ones of magnitude 2-3) probably weren't perceptible. If you think that the number of small earthquakes has changed over a short time, it would be more useful to compare records for (for example) this year with ten years ago, rather than just giving a number for the present day. $\endgroup$ – Semidiurnal Simon Jan 9 '16 at 9:09
  • $\begingroup$ @SimonW Actually if you look at the site, it's only in Oklahoma, and it's a magnitude 1.5 or greater.. $\endgroup$ – Bam Jan 11 '16 at 12:01
  • $\begingroup$ Interesting. I stand corrected! $\endgroup$ – Semidiurnal Simon Jan 11 '16 at 13:56
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The sudden and recent occurrence of multiple earthquakes in Oklahoma is due to a widespread redistribution of stresses within the ground, particularly at depth.

Installing large pipes underground for storm water, waste water, or potable water or even digging a basement under every house in an entire city will only cause a very minor localized redistribution of ground stresses, near the Earth's surface. Such minor redistributions of stresses will not lead to earthquakes.

As Blaydes states, injection of fluids and fracking will induce additional stresses and they can also lead to faults and ground fissures becoming lubricated and thus prone to movement, resulting in earthquakes.

Removal of a liquid from an underground reservoir, oil or water, can have an adverse impact. If the reservoir is naturally pressurized, tapping the reservoir will reduce its pressure and the affect that has on the surrounding rock.

Depending on the circumstances, releasing pressure can unlock rock, allowing it to move. It's a bit like having a number of blocks of lumber clamped together by a vice a or a clamp. Provide enough stress (clamping force) and everything is held together nicely. Too much stress and the blocks become damaged due to the strength properties of the individual blocks. Not enough stress and the blocks become free to move relative to one another.

It is well documented, particularly in the US, that removal of water and oil from underground reservoirs can cause surface subsidence. In the case of the Lost Hills and Belridge oil fields in California, subsidence rates of up to 40 mm/day (greater than 400 mm per year) were measured. In the Wilmington oilfield at Long Beach, California, an area 50 square kilometres subsided. In the centre of the subsidence area the maximum subsidence was 9 meters.

The removal of liquids from underground reservoirs results in a reduction of fluid pressure which causes the pore spaces to close and the sediments to compact, resulting in subsidence. As the sediments compact the rock above it also subsides. Under certain circumstances, such ground movements can induce earthquakes.

In Oklahoma's situation, oil pumping, fracking and fluid injection into oil wells are very likely candidates for the causes of earthquakes experienced there.

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  • $\begingroup$ And yet we keep doing it.. $\endgroup$ – Bam Jan 8 '16 at 12:27
  • $\begingroup$ Good additional information Fred, that is true that production form wells lowers fluid pressure in the pore spaces, that is in fact what creates flow! $\endgroup$ – blaydes Jan 8 '16 at 16:40
  • $\begingroup$ Oops, wasn't finished with my thought.... generally managing pressure in the reservoir is beneficial to oil and gas production to maintain flow for long term production. Often the pressure is maintained by reintroduction of produced brine through injection wells associated with the production wells to continue the flow of oil and dispose of the produced water. Those fields that are truly $\endgroup$ – blaydes Jan 8 '16 at 17:19
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Short answer is that no this is not normal, which is why there are experts descending on the area to study the situation.

Your first theory is not likely to be an issue, as oil is produced from a well, the fluids from the surrounding area move into the now available space which leaves the subsurface in a situation that isn't terribly dissimilar to what had been. The oil is produced from tiny spaces in a rock supported matrix and fluid remains present after production, this has some effect but not typically significant, either water will intrude to fill the space, or the reduced pressure will allow gas to expand and fill the space, but the rock matrix provides the support.

Injection of fluids can have a significant effect though, the point of pressure from the injection changes the dynamics of the rocks that are taking on the fluid, which must be injected with enough force to overcome the fluid pressure present in the rocks and induce flow through the pore spaces. The injection could be managed so that the pressures used are just slightly above what is necessary to induce flow, but those flow rates would be very low compared to what is desirable for waste disposal, so higher pressure is used, which can trigger seismic events.

Hydraulic fracturing takes this even further, using very high pressure and large volumes of fluids to induce new open flow paths in the rocks, and this certainly has some effect, and can trigger seismic events. Imagine that you have two large blocks of rock that want to slide past each other but are holding the tension without moving, and then someone injects a lubricant that reduces the friction between the two, the friction is reduced to the point that motion will occur.

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  • $\begingroup$ That's a very well thought out answer. We've had over 20 in the past 24 hours. $\endgroup$ – Bam Jan 7 '16 at 19:22
  • $\begingroup$ just to add: I don't think it can be said the effect from production is not typically significant. There are many examples where production-induced contraction of the rock matrix caused an increase in seismicity. The guy from OU who is cited in the article seems to assume that itsthe case here, too $\endgroup$ – ye-ti-800 Nov 4 '17 at 21:36

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