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Study finds big earthquakes can trigger tremors at U.S. oil and gas sites

AFP-JIJI

Large earthquakes around the world have been found to trigger tremors at U.S. sites where wastewater from gas drilling operations is injected into the ground, a U.S. study said Thursday.

For instance, the massive 9-magnitude earthquake off the coast of Japan in 2011 set off a swarm of earthquakes in the western Texas town of Snyder, near Cogdell oil field, culminating in a 4.5-magnitude quake there about six months later, according to research in the journal Science.

Similarly, small- to mid-size quakes were observed near active injection wells in Prague, Oklahoma following an 8.8-magnitude quake in Chile in 2010.

Uncommon seismic activity stirred that region 16 hours after the Chile quake with a 4.1-magnitude tremor, and it continued until a 5.7-magnitude quake in November 2011, said researchers at Columbia University’s Lamont-Doherty Earth Observatory.

The 2010 Chile quake also led to heightened seismic activity in Trinidad, Colorado, including a 5.3-magnitude quake in August 2011, in an area where methane is extracted from the coal bed and wastewater is reinjected into the Earth.

“We weren’t really confident until we found the same pattern of little bursts of seismicity following the passage of seismic waves from several of these big earthquakes,” lead author Nicholas van der Elst of Columbia University said.

“Any individual case could be a coincidence but once you start observing it systematically, then you can have more confidence that you are really looking at a physical relationship.”

The study helps explain a surge in earthquakes in the central United States, which in recent years has seen a more than six-fold increase in earthquakes over 20th century levels.

An accompanying study in Science said there were 300 3-magnitude or higher earthquakes in the central United States from 2010 to 2012, after an average of 21 such quakes per year from 1967 to 2000.

The change coincides with a growing natural gas boom that is based on using large amounts of fluids to crack open rocks for natural gas, known as hydro-fracturing or fracking.

Then, once gas and oil have been extracted from deep within the Earth, companies often inject the wastewater back below the surface.

The U.S. Department of the Interior last year also acknowledged an uptick in seismic activity — predominantly in Texas, Colorado, Arkansas, Oklahoma and Ohio — where disposal of wastewater through injection wells has “increased significantly,” it said.

One of the earliest known cases of wastewater inducing earthquakes dates back to the Rocky Mountain Arsenal Well near Denver, Colorado, where large amounts of wastewater were injected from 1962 to 1966, leading to a series of earthquakes below magnitude 5, the DOI said.

Scientists have long known it is possible for quakes to stir up regions of the Earth far away, even in natural circumstances such as hydrothermal fields where there is already high fluid pressure.

But the new research raises questions about how to manage the risks of causing quakes associated with oil and gas extraction and disposal of wastewater in underground wells.

“These passing seismic waves are like a stress test,” said co-author Heather Savage, a physicist at Lamont-Doherty.

“If the number of small earthquakes increases, it could indicate that faults are becoming critically stressed and might soon host a larger earthquake.”

The largest so far has been the 5.7-magnitude quake on Nov. 6, 2011, in Prague, Oklahoma, triggered by the Chilean quake a year earlier.

The U.S. quakes have been felt by many people but have caused minimal damage and no deaths, though researchers point out that elsewhere in the world, similarly strong quakes have resulted in massive damage and loss of life.

Scientists have no way of predicting when a particular field has reached a dangerous point, which van der Elst and colleagues described as a “key problem in developing operational strategies” to lessen the earthquake risk posed by human activities.

In an accompanying article in Science, William Ellsworth of the U.S. Geological Survey framed the problem another way.

“Ignorance of the things that we understand we should know but do not leaves us vulnerable to unintended consequences of our actions,” he said.

  • http://www.sheldonthinks.com/ andrew Sheldon

    It would be wrong to attribute any causal relationship insofar as quakes are ‘causing’ quakes, which might be construed as ‘reducing’ the severity of an otherwise deferred quake. It that respect it could be construed as a good thing, in the same way that small quakes reduce the threat of a big one. This is most particularly the case with coal seam gas extraction because its over big areas. It needed to be said because the greenies have long been using this as an argument against fracking.

    • leconfidant

      Fair point.
      Sooner or later, there’s going to be an earthquake everywhere. However if the oil fields,
      through this mechanism,
      concentrate current seismic activity around the fracking location,
      it’s is going to affect the people living in that place at that time,
      rather than at at some distant sooner-or-later point.
      And they’re going to complain at the time when it happens.

  • TO

    Thanks for the article. It’s one more reason to stop “fracking” – natural gas, sand, etc. that President Obama recently tauted, thanks largely to the political pressures and money from the gas industry (gov. agencies are also corrupted with industry-friendly appointees). Along with the dangers of methane contributions to the climate change (up to 100 times more contributing than CO2), water, air, soil pollution and health consequences, who pay the price for this short-term economic benefits for some? Isn’t it high time to think seriously about how to reorganize the whole system and lifestyle?

    Watch the academy award-nominated documentary, “Gasland”, and “Gasland II” just aired on TV, despite the gas industry’s well-funded PR campaign to discredit them.

  • Osaka48

    Radical environmentalists are determined to stop “fracking” even with questionable theories. Even the U.S. (liberal) EPA has given the “green light” to fracking after numerous studies, yet while this technology is delivering energy independence and job growth to the U.S., the “greenies” are determined to stop it.

    As stated, minor earthquakes have caused no damage, but “dire” predictions are forwarded as a convenient discouragement to gas and oil extraction.

    How about “clean” hydro-electric power? It has been known for years that dams, such as Egypt’s Aswan dam, or the filling of Greece’s Lake Kremasta (1982) have induced earthquakes due to the ‘weight’ of the resevoir’s water. What should we expect from China’s ‘Three Gorges’ dam?

    We can assume that the “greenies” are also opposed to hydro-electric power due to the known earthquake risks associated with dams. Let’s summarize:

    Radical environmentalists are against:

    - The known benefits of oil, gas extraction from fracking and want to stop it.
    - Are against nuclear power.
    - Are against coal-fired plants.
    - Are against hydro-electric power (fish disturbance, earthquakes?)

    That leaves ‘wind mills’ which kill 10′s of thousands of birds per year (greenies tend to ignore this)…and which have nearly wiped one endangered species in one Calif. wind mill park alone.

    I can’t run my car, heat my home from ‘methane’ generated from personal composting. Solar panels are not cost effective…but this seems to be the objective of radicals who would have us freezing in the Winter, and riding bikes to work after their agenda of: “disruption of conventional energy at any cost is fulfilled.

    No thanks. The world has enormous reserves of natural gas…more since fracking, and we should take full advantage of this energy supply.

  • leconfidant

    This puts a limit on the ‘Act of God’ clause in the insurance, I suppose.