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Deadly quake linked to water extraction

2012-10-22 07:34

Washington - An earthquake that killed nine people in Spain in 2011 may have been triggered by decades of pumping water from a nearby natural underground reservoir, suggesting human activities played a role in moving Earth's crust, scientists reported on Sunday.

The study published in the journal Nature Geoscience centred on the 11 May 2011 quake in the southern Spanish town of Lorca. In addition to the nine deaths, this relatively modest earthquake of magnitude 5.1 damaged numerous buildings in Lorca, an agricultural centre.

The study's lead author, Pablo Gonzalez of the University of Western Ontario, said he and his colleagues reckoned that the quake was related to a drop in the level of groundwater in a local aquifer, which can create pressure at the Earth's surface.

To test that theory, they used satellite data to see how the terrain was deformed by the earthquake, and found that it correlated to changes in the Earth's crust caused by a 250m drop in the natural groundwater level over the last five decades due to groundwater extraction.

Their findings suggest that human-induced stress on faults like the one near Lorca, known as the Alhama de Murcia Fault, can not only cause an earthquake but also influence how far the fault will slip as a result.

Implications

The groundwater was tapped by deeper and deeper wells to irrigate fruits and vegetables and provide water for livestock.

While this research does not automatically relate to other earthquakes, it could offer clues about quakes that occur near water in the future, Gonzalez said by telephone.

"We cannot set up a rule just by studying a single particular case, but the evidence that we have collected in this study could be necessary to expand research in other future events that occur near... dams, aquifers and melting glaciers, where you have tectonic faults close to these sources," Gonzalez said.

He said this was different from a rash of minor earthquakes seen in Texas over the last two years, some of which occurred near wells where wastewater was injected deep underground.

In an accompanying article, Jean-Philippe Avouac of the California Institute of Technology said the implications could be far-reaching "if ever the effect of human-induced stress perturbations on seismicity is fully understood."

"For now, we should remain cautious... We know how to start earthquakes, but we are still far from being able to keep them under control," Avouac wrote.

Comments
  • John - 2012-10-22 07:53

    Wow, this is an interesting story! It makes absolute sense too, a huge cavity formed after we suck the underground reservoir dry and the earth around it crumbles. Where does that leave Africa and all the boreholes we have in dry areas? Surely we will have a similar problem here sometime?

      steve.barrow.104 - 2012-10-22 08:00

      Add Fracking to the mix and let's see what happens.

      jacowium - 2012-10-22 08:03

      Yep. It's a terrible reality, as we need that water for consumption and agriculture - which reflects on the root cause of all our impending problems: we've overpopulated the earth. Not pointing fingers...I'm one of the "too many".

      Tony Lapson - 2012-10-22 08:23

      Would humans require so much of the earths resources if they were able to control their breeding habits?

      les.sterrenberg - 2012-10-22 09:34

      Surley one should also look to the oil well's then.

  • bob.moodley.9 - 2012-10-22 09:49

    stop the fracking in south africa

  • horst.muller.7330 - 2012-10-22 13:59

    Well, its a theory. But lets not forget earthquakes are the result of tectonic plate movement. Its got nothing to do with the level of the ground water. Although I concede that lack of water could possibly cause some 'stickiness' resulting in more stress building up before the final release into an earthquake.

      steve.barrow.104 - 2012-10-22 14:52

      You are only refering to Tectonic Earthquakes. Try looking up Induced seismicity. Here is a link to start you off: http://en.wikipedia.org/wiki/Induced_seismicity

  • zionpercival.pay - 2012-10-22 16:43

    During the early years of the construction of the Hoover dam this phenomenon was rampant and the aquifers were recharged from the surface. drainage was due to huge farming operations.

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