Tuesday, October 23, 2012

Deadly 2011 earthquake linked to groundwater extraction

Getting ready: Newberry Crater project drilling manager Fred Wilson at the site in May 2008. This summer, engineers will pump water into the Oregon volcano to see if they can generate electricity from the earth's heat -- Story: Quake feared as Google, US to pump water into Newberry volcano to make power
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Deadly 2011 earthquake linked to groundwater extraction

An earthquake that killed nine people in Spain last year 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 centered on the May 11, 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 center.

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 273-yard (250-metre) 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.

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

Story: http://mobile.reuters.com/article/scienceNews/idUSBRE89K0HT20121021?irpc=932