Fracking could lead to an ‘earthquake domino effect’ as it weakens fault lines deep in the earth’s crust, scientists claim
- Scientists from Columbia University have claimed that earthquakes could be caused by pressure on fault lines created by hydraulic fracturing
- Danger occurs when the activity is agitated by distant earthquakes that can trigger tremors near waste water injection wells, they said
- Seismologists from the university have identified three quakes that were triggered at injection well sites by a major earthquake a long distance away
PUBLISHED: 09:22 EST, 12 July 2013 | UPDATED: 09:22 EST, 12 July 2013
Fracking could cause powerful earthquakes capable of destroying buildings as the process of extracting gas weakens fault lines deep under ground, scientists have claimed.
American geologists said that a domino effect of quakes could be caused by intense pressure on fault lines created by hydraulic fracturing, combined with seismic activity thousands of miles away.
Columbia University scientists maintain that powerful earthquakes thousands of miles away can trigger swarms of minor quakes near waste water injection wells like those used for in oil and gas recovery.
They say a recent surge in U.S. oil and gas production using vast amounts of water to crack open rocks and release natural shale gas has been linked to an increase in small to moderate induced earthquakes in five states.
Seismologists from the university have identified three quakes – in Oklahoma, Colorado and Texas that they believe were triggered at injection well sites by a major earthquake a long distance away.
The discovery, published in the journal Science by one of the world’s leading seismology labs, threatens to make fracking even more controversial, Reuters reported.
Geologists have known for 50 years that injecting fluid underground can increase pressure on seismic faults and make them more likely to slip. The result is called an ‘induced’ quake.
Nicholas van der Elst of Columbia’s Lamont-Doherty Earth Observatory in New York, who led the study, said: ‘The fluids (in waste water injection wells) are driving the faults to their tipping point’.
He believes that as pressure from waste water wells stresses nearby faults, if seismic waves speeding across Earth’s surface hit the fault it can rupture and months later, produce an earthquake stronger than magnitude 5.
The seismologist thinks that waste water injection leaves local faults ‘critically loaded,’ or on the verge of rupture.
Even weak seismic waves arriving from faraway quakes are therefore enough to set off a swarm of small quakes in a process called ‘dynamic triggering.’
And once the tremors stop the danger is not necessarily over.
Heather Savage, co-author of the study warned that the swarm of quakes ‘could indicate that faults are becoming critically stressed and might soon host a larger earthquake’.
The seismologists believe that long distance triggering is most likely where waste water wells have been operating for decades and where there is little history of earthquake activity.
Opponents of fracking fear that the process will release toxic chemicals into water supplies.
John Armstrong, a spokesman for advocacy group New Yorkers Against Fracking, said that the new study should be ‘a stark warning’.
The study was funded by National Science Foundation and the US Geological Survey.
However, many scientists have previously suggested that fracking will not lead to major earthquakes.
Geologist William Ellsworth of the US Geological Study, who was not involved in the study but is an expert on human-induced earthquakes, said that tremors that cannot be felt are routinely produced by fracking.
The largest fracking-induced earthquake ‘was magnitude 3.6, which is too small to pose a serious risk,’ he write in Science.
A previous study into fracking led by Professor Richard Davies from Durham University’s Energy Institute, said the risk of fracking resulting in seismic activity that could be felt on the surface is ‘not significant’.
Talking about whether the process of extracting shale gas causes seismic actiivity itself, he said: ‘In almost all cases, the seismic events caused by hydraulic fracturing have been undetectable other than by geoscientists.’
‘Most fracking-related events release a negligible amount of energy roughly equivalent to or even less than someone jumping off a ladder onto the floor.’
A joint UK study of hydraulic fracturing by The Royal Society and the Royal Academy of Engineering said that fracking can be managed effectively in the UK as long as operational best practices are implemented and robustly enforced through regulation.
The experts also said that earth tremors induced by hydraulic fracturing are likely to be of a smaller magnitude than the UK naturally experiences or than is related to coal mining activities.