Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. Earth Science News .




SHAKE AND BLOW
Water extraction helped trigger deadly quake in Spain: scientists
by Staff Writers
Paris (AFP) Oct 21, 2012


Massive extraction of groundwater helped unleash an earthquake in southeastern Spain last year that killed nine people, injured at least 100 and left thousands homeless, geologists said on Sunday.

The finding adds a powerful piece of evidence to theories that some earthquakes are human-induced, they said.

Seismologists were surprised by the May 11, 2011 earthquake which happened two kilometres (1.2 miles) northeast of the city of Lorca.

The quake struck in the Eastern Betics Shear Zone, one of Spain's most seismically active regions, where there has been a large number of moderate-to-large temblors over the last 500 years.

But the May event was unusual because it was so devastating and yet so mild -- only 5.1 magnitude -- in terms of energy release.

Researchers led by Pablo Gonzalez of the University of Western Ontario in Canada probed the mystery.

Reporting in the journal Nature Geoscience, they found that the quake occurred at a very shallow depth, of just three kilometres (1.8 miles), so the shockwave swiftly reached the surface with little to dampen it on the way.

The quake also happened on a complex but dormant fault that ripped open after water had been extensively pumped out of a neighbouring aquifer, causing a domino effect of subterranean stresses, they said.

Gonzalez' team first used ground-radar imaging by the European satellite Envisat to build a map of how terrain around Lorca changed before and after the quake.

The picture confirmed that the event had occurred on the so-called Alhama de Murcia fault, which slipped between five and 15 centimetres (two and six inches).

They then investigated the Alto Guadalentin Basin, an aquifer lying just five kms (three miles) south of the fault, where they found widespread evidence of subterranean subsidence from water extraction.

Between 1960 and 2010, the level of groundwater from this aquifer fell by at least 250 metres (812 feet), according to records from local wells.

A computer model put together by the team suggests what happens: lowering of the water table caused part of the crust, located next to the Alhama de Murcia fault, to break.

This led to an "elastic rebound" of the crust that in turn cranked up horizontal pressure on the fault, bringing it that much closer to rupture.

The investigation adds to anecdotal evidence that human activities, ranging from exploration for shale gas, quarrying and even water reservoirs, can cause quakes.

"Our results imply that anthopogenic [man-made] activites could influence how and when earthquakes occur," said the study.

In a commentary, Jean-Philippe Avouac, a geologist at the California Institute of Technology (Caltech) said water extraction at Lorca probably accelerated a natural process of stress accumulation rather than unleashed the earthquake by itself.

Even so, "the consequences are far-reaching," said Avouac.

He pointed to carbon storage, a still-experimental technique in which carbon dioxide from a fossil-fuel power station is pumped into underground caverns rather than released to the atmosphere, where it would add to global warming.

"For now, we should remain cautious of human-induced stress perturbations, in particular those related to carbon dioxide sequestration projects that might affect very large volumes of crust," said Avouac.

"We know how to start earthquakes, but we are still far from being able to keep them under control."

.


Related Links
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





SHAKE AND BLOW
JPL Scientists Participate in ShakeOut Exercises
Pasadena CA (JPL) Oct 22, 2012
On Thursday, Oct. 18, at 10:18 a.m. PDT, more than 9.3 million Californians, including employees at NASA's Jet Propulsion Laboratory, Pasadena, Calif., "dropped, covered and held on" during the 5th annual Great California ShakeOut, the world's largest earthquake drill. The purpose of the ShakeOut is to encourage people and organizations to be prepared to survive and recover when the next big ear ... read more


SHAKE AND BLOW
Japan saves 64 Chinese seamen from burning freighter

Clinton hails Haitian post-quake reconstruction

Haiti leader under fire for rising prices, corruption

Tiny travelers from deep space could assist in healing Fukushima's nuclear scar

SHAKE AND BLOW
Apple opens biggest Asian store in Beijing

Will Apple go for 'kill' with iPad Mini?

Taiwan temple to launch 'divine advice' app

Kennedy Supporting Effort to Develop Satellite Servicing Capabilities

SHAKE AND BLOW
Egypt pushes Ethiopia to scrap Nile dam

EU states agree to cut Baltic cod quotas

Brazil resumes work on major dam after protests

Wave snatches Polish woman to her death in Spain

SHAKE AND BLOW
Green groups presses Antarctica meet to expand marine haven

Ice sheet retreat controlled by the landscape

1 by land and 1 by sea

NASA's Operation IceBridge Resumes Flights Over Antarctica

SHAKE AND BLOW
Panels reject study on GM corn but urge wider probes

Indian farmers cotton on to sustainable farming

Pesticides have knock-on effect for bees: study

Some 500 scientists have created a Top 10 list of plant-damaging fungi

SHAKE AND BLOW
Italian scientists sentenced to jail in quake trial

JPL Scientists Participate in ShakeOut Exercises

Hundreds of pilgrims evacuated as floods swamp Lourdes

Floods in S.Africa kill eight

SHAKE AND BLOW
Fear stalks DR Congo's rebel-held territory

Argentina: UN an option over Ghana ship seizure

Guinea-Bissau blames Portugal after foiled coup bid

Attacks, clash in north Nigeria kill several, burn buildings

SHAKE AND BLOW
Japanese lake record improves radiocarbon dating

Novel chewing gum formulation helps prevent motion sickness

Discovery of two opposite ways humans voluntarily forget unwanted memories

The evolutionary origins of our pretty smile




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement