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An fracturing oil rig in Garfield County.

Water impoundments like this one beside a Colorado oil rig are typical at hydraulic fracturing sites. Underground disposal of the wastewater after fracking may increase seismic risks from remote earthquakes, a new study says.

Photograph by Lynn Johnson, National Geographic

Ker Than

For National Geographic

Published July 11, 2013

Fracking for oil and natural gas, and the underground disposal of wastewater that occurs in the process, has been linked to earthquakes in recent years. Now seismologists have discovered a new twist in that relationship, finding that wastewater injection can also contribute to temblors induced remotely by faraway seismic events.

The finding, detailed in this week's issue of the journal Science, is the latest research to show how humans can influence earthquakes. The study found that industrial wastewater disposal made certain areas more prone to seismic activity in the wake of a larger event, linking quakes near wastewater injection sites in the United States to those as far away as Japan and Chile.

"The fluids are driving the faults to their tipping point," lead author Nicholas van der Elst, a seismologist at Columbia University's Lamont-Doherty Earth Observatory, said in a statement.

Scientists have known about "dynamically triggered" temblors for over 20 years, and certain regions were known to be more vulnerable to such earthquakes than others, especially those where underground water superheated by magma can weaken faults and make them more vulnerable to seismic waves generated by a distant quake.

For example, a magnitude 7.9 earthquake in Alaska in 2002 triggered a series of quakes at Yellowstone National Park—nearly 2,000 miles (3,219 kilometers) away—throwing off the schedules of some of its most predictable geysers.

"We had some idea for some time that these fluid-rich systems tend to be sensitive to this kind of triggering," said study coauthor Heather Savage, a geophysicist also at Lamont-Doherty.

Knowing this, van der Elst and his team wondered if areas where humans have artificially created a fluid-rich environment would also be prone to triggered quakes.

Seismic Chain Reactions

To answer this question, the researchers analyzed a catalog of past earthquake recordings in the United States. They focused on earthquakes that occurred shortly after three large quakes: an 8.8-magnitude earthquake in Chile on Feb. 27, 2010, the 9.1-magnitude event off the coast of Japan on March 11, 2011, and an 8.6-magnitude quake in Sumatra, Indonesia on April 12, 2012.

"We saw that three areas in particular have an increase in seismicity in the days following these big events," Savage explained. "These areas were in Texas, Colorado, and Oklahoma."

Most of the triggered quakes occurred in clusters and were too small for humans to notice, but others were more significant. For instance, a 4.1 magnitude triggered quake shook the town of Prague, Oklahoma about 16 hours after the 2010 quake in Chile.

One thing the affected areas in the three states all had in common was that they were located near sites where wastewater injection had been ongoing for decades.

Hydraulic fracturing (or fracking) uses large amounts of water to crack open rocks and help coax oil and gas from underground wells. (See interactive: "Breaking Fuel From the Rock.") After the gas and oil have been extracted, the chemical-laced water is typically pumped back underground. (See related blog post: "Tracing Links Between Fracking and Earthquakes.")

Other research has shown that this practice can induce earthquakes on its own by increasing the pressure on faults and leaving them on the brink of rupturing.  For example, a study published earlier in March in the journal Geology concluded that a magnitude 5.7 event that struck Prague in 2011—the largest recorded earthquake in the Oklahoma's history—was an induced quake likely triggered by wastewater injection from oil production into wells deep underground. (See related story: "Scientists Say Oil Industry Likely Caused Largest Oklahoma Earthquake.")

A Way to Probe Faults?

It's still unclear why faults that lie near sites with underground water reservoirs are more vulnerable to triggered earthquakes.

"Dynamic triggering itself is actually a very poorly understood phenomenon," said Emily Brodsky, a geophysicist at the University of California, Santa Cruz (UCSC), who was not a coauthor of the current study.

One idea is that the process of wastewater injection leaves local faults "critically loaded" by increasing the fluid pressure exerted on pores in the rock, so that even weak seismic waves from distant earthquakes are enough to disturb them and cause a rupture.

"If you think of a rock like a sponge, you can imagine that fluid resides in the tiny pore spaces between grains," Savage explained in an email. "When fluid pressure is jacked up on faults, like when we pump pressurized fluid underground, it makes faults slip.  It's the same concept as an air hockey table: When the air is turned off, it's harder to make the puck slide.  When the air is turned on (increase the fluid pressure) the puck (fault) slides more easily."

UCSC's Brodsky called the findings by van der Elst and his colleagues "totally cool" because it means scientists can use dynamically triggered earthquakes to gauge the health of a fault to see if it's close to failure.

To be able to "probe and know what those faults are doing kilometers underground simply by watching how they react to passing seismic waves—that's new," Brodsky said.

Brodsky is the coauthor of a separate study, also appearing in this week's issue of Science, that suggests pumping water into and out of an underground reservoir to produce geothermal power can also induce earthquakes.

The findings by van der Elst's team could also help energy companies decide whether pumping wastewater underground is worth the risk of increasing the chances of a triggered quake at a site, Brodsky said.

"That's why it's so important to put numbers to this," Brodsky said, "so that you can really explore the cost-benefit."

This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.

14 comments
Leona Collet
Leona Collet

Fracking will never become green, if it continues to pump chemically laced water back into the earth and contaminates groundwater resources. And for fracking contributing to earthquakes; if this is proven, it gives another reason to STOP this insidious practice. And it may even contribute to land sinkholes.

Beth C.
Beth C.

Even though my step-son is a mechanic for one of the larger fracking companies, I still believe we need todo a serious study on the effects of our environment, farming, & water sources!

David Hunt
David Hunt

I suggest using an English word for earthquake such as tremor rather than the Spanish work "tremblor."  I know it is trendy, but is simply wrong.

Ads for the story, I see no evidence mentioned that disposal of fracking fluids even facilitates eartquakes, let alone causing them. You would need to trace the eartguake to a specific area where disposal had occruured. It makes sense this would happen, but a well written article would be much more careful about the facts and science.

Andrew Booth
Andrew Booth

The future global water shortage is going to have a far more direct and devastating effect than fuel or even food shortages. 

Fossil ground water has taken tens of thousands of years to accumulate and it's not replaceable. Yet ground water is being extracted and polluted on such a scale that it will effectively be gone in the next few decades. Areas such as Africa, India, Australia, Europe, China, the US plains and mid-west regions are already suffering the irreversible effects of increased ground water extraction - yet the abuse of our water reserves marches blindly on for short-term gain.

NAT GEO
NAT GEO

Albert,

Too many people fancy their lack of knowledge is just as valuable as other peoples actual knowledge. In Texas there are earthquakes happening in places earthquakes have never been recorded since they started monitoring them. It is just a coincidence they are ALWAYS within 10 miles of a fracking site.

I personally do not believe in coincidences.

I have been saying for years that it is not about the oil. Its about the water.
How long can you live without oil? How long can you live without water?

The fracking and injection of waste water is being done to contaminate the water. Then the corporations will charge the masses 20 dollars a gallon for drinkable water. Or even more.

If anyone does any research at all into this, fracking causes job losses, and many companies are going in the red by fracking, but continue to do so.

Why would you frack for a loss, then repeat that knowing full well the next hole will also be a loss.

Its isn't about the oil, its about the water.

Albert Cadda
Albert Cadda

While everyone is voicing their opinion of the pros and cons of fracking, there's one thing that most people are overlooking; we are using up our fresh groundwater supply.  The water table is dropping faster than it can be restored through the natural process that put it there in the first.

We may be "solving" our energy problems for now, but in the process we are creating a fresh water crisis that is going to make our energy crisis pale by comparison.  There are no easy answers but, fracking is NOT one of them.

Re: Movie, "Gasland"; Part One & Two.

Charles Becker
Charles Becker

Risk vs rewards

No matter what we do there is risks.  Increased drilling with an effort to begin exporting significant amount of Natural Gasses from these regions will help our GDP, and job rates, dare I say deficit.  Putting a “Moratorium” on unconventional would destroy an industry feeding thousands of families.  Not to mention tight oil plays such as Monterey Sale, Bakken Shale, Permian Basin, Utica, Eagle Ford, ect. utilize unconventional techniques.  Nearly 60 percent of all wells are unconventional, we as a nation can not afford to say OK everyone stop!   It is not feasible to ban, we need to fix.  The answer is for these companies to start developing better and more friendly technologies.  Acid wells may be an example but it does not solve the water table issue in the event of a poorly completed well.  We can live life prancing through wild flowers with unrealistic imagery of big oil companies not caring and killing off renewable energies or we can fix what we have now as these “cleaner” energies are the future but need to be  further developed and widely available.  XOM, Shel, BP, StatoIl ect., are investing in these energies; they have a vested interest in alternative energies for company survival.  Don’t be so quick to judge what is supporting this nation.  


Joanne Corey
Joanne Corey

Many drilling waste injection wells are located in the central US.  What are the implications for induced seismicity from a major quake on the New Madrid? Could its next quake induce a cascade of quakes near drilling waste disposal wells?  As unintended consequences, accidents, increased risks, and scientific evidence of negative impacts mount, it's time for a moratorium on unconventional fossil fuel development. The industry's claims of safety ring hollow with each new study or news report.

Ashok Manvati
Ashok Manvati

An observation with far reaching consequences !

Timothy Steele
Timothy Steele

It's easy to understand why increasing pressure along fault lines with underwater reservoirs causes fault slippage and as a result seismic activity in the areas. Water is not compressible. That pressure has to go somewhere. It's just the most recent display of the oil and gas industries blatant disregard for the planet and the people on it. They really don't give a s*** if they make your house fall down as long as they can sell another few pounds of fuel.

Other Mike
Other Mike

In another study, non-coauthor Bernard Ignacio Gerald Foote showed that just prior to every earthquake ever felt on earth, people were walking around on TOP of the earth.  There is believed to be a 100% correlation between people walking and earthquakes.  "The evidence is irrefutable," noted B.I.G. Foote, who then disappeared into the forest.

Albert Cadda
Albert Cadda

@NAT GEO Thank you for the Reply.

To give further credence to this "argument", everyone should read about what is happening to the water tables all over the world.  And, you don't have to go very far to learn of this subject.  It's right here at "Nat Geo".

http://news.nationalgeographic.com/news/2012/12/121218-grabbing-water-from-future-generations/

Today it's "oil" that we are fighting over; tomorrow it will be "water".  Whenever there is natural gas, the world's biggest aquifer, a haven for every despot in the world, and a military build up, you will find a Bush.

http://www.bibliotecapleyades.net/sociopolitica/esp_sociopol_bush53.htm

Timothy Steele
Timothy Steele

@Other Mike yes yes yes and every person alive on the earth today will die from a 30 lb banana falling on them if they dont die of something else first. you're an idiot if you are making this asinine statement simply because you don't agree with the evidence. 

Other Mike
Other Mike

@Timothy Steele @Other Mike "For example, a study published earlier in March in the journal Geology concluded that a magnitude 5.7 event that struck Prague in 2011—the largest recorded earthquake in the Oklahoma's history—was an induced quake likely triggered by wastewater injection from oil production into wells deep underground."

Uhm, 'likely triggered'?  You consider that as evidence?  Sounds like biased conjecture to me.  You know, the whole, "make the 'facts' fit the theory" garbage.

I'm sticking with the B.I.G. Foote Theorem.  It's more plausible.

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