Is It True That Human Activity Can Trigger an Earthquake?

Years ago there was an earthquake measuring 5.1 on the Richter scale in Spain that killed nine peoples. Apparently the quake was not caused by a collision of the plates or fracture / fault. The trigger is pumping water for decades of underground water sources near the center of the quake.

"It suggests human activity played a role in moving the earth's crust," said Pablo Gonzalez of the University of Western Ontario, Tuesday, October 23, 2012.

Are we destablising the ground
beneath our feet? (Picture from:
 http://www.newscientist.com/)

Gonzalez and his colleagues examined the link between earthquakes and the decline of groundwater levels in water reservoirs (aquifers) in the basement. For this condition Gonzalez theorized could create pressures that led to the quake.

Research published in the journal Nature Geoscience focused on the earthquake in Lorca, a region in southern Spain, on May 11, 2011. The quake was not large relative strength is not only claimed nine lives, but also damaged many buildings in the farming areas.

To test the theory, Gonzalez and his colleagues used satellite data to see ground deformation caused by the earthquake. They found that the deformation was associated with a shift in the earth's crust due to the natural decline in groundwater levels. "The reduction is as deep as 250 meters during five decades as groundwater extraction," said Gonzalez.

Their findings suggest that the pressure of human activities on faults near Lorca (known as the Alhama de Murcia fault) not only can cause earthquakes. Human intervention also affects how much delivery will slip. Lorca groundwater tapped by the wells in order to irrigate plantations of fruit and vegetables and livestock drinking water.

May 2011: The earthquake in Lorca killed nine people and destroyed hundreds of homes. (Picture from: http://www.telegraph.co.uk/)

Gonzalez said that the study could offer clues about the future earthquake near water sources. "We should be wary of dams, aquifers, and the melting of glaciers that are located close to the tectonic fault," he said.

Nevertheless, at Lorca different phenomena minor earthquakes in Texas for two years. Some of these earthquakes occurred near wastewater disposal wells deep 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.. *** [REUTERS | MAHARDIKA SATRIA HADI | KORAN TEMPO 4036]

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