Fracking can cause earthquakes tens of kilometres away – new research

Property damage risk from hundreds of earthquakes above magnitude 3 in a large area of Oklahoma. Credit: US Geological Survey/Wikimedia Commons

Earthquakes threaten to be a show-stopper for fracking. In the Netherlands, the largest gas field in Europe will be shut down by 2030 after sustained damage to homes from earthquakes became too severe. In Oklahoma, US officials have severely curtailed operations after injection of waste water underground caused several earthquakes above magnitude five – one nearly 180,000 times stronger than the 2.3 magnitude earthquake that brought a seven-year pause on fracking in the UK.

While operations have since resumed in Britain, the practice still remains a political battleground, with earthquakes at the centre. The UK government's fracking commissioner, Natascha Engel, recently resigned, claiming that an [unreasonably low] magnitude 0.5 threshold for tolerated earthquakes amounted, in effect, to a ban on fracking.

Residents, on the other hand, largely oppose fracking near their homes. Fears of damage to property and the well itself at a fracking location in Lancashire, in the north of England, notably lowered house prices in the area.

In the absence of a known mechanism by which fracking could cause earthquakes more than a mile or two from drilling sites, operators have often denied responsibility for such quakes. However, new research has now linked distant earthquakes to fracking, providing evidence that much larger areas surrounding sites may be at risk from drilling operations than previously demonstrated. This is a critical problem not only for fracking, but for cleaner energy solutions too.

Seismic slip

Fracking involves injecting a high-pressure mixture of water, sand, and chemicals into shale layers to create fractures, opening pathways along which trapped gas in the shale can be extracted. Once this waste water has served its purpose, it can be reused for fracking injections at another site. By design, the breaking of rock that inevitably accompanies both waste water disposal and fracking produces small, usually imperceptible earthquakes.

Occasionally though, the injection of fracking fluid or waste watercan cause movements in natural pre-existing geological faults – large cracks that already exist in the rock. This can trigger the release of loaded energy stored in the fault, in much the same way a skier can trigger the release of an avalanche. If sufficiently severe, the resulting earthquake can cause damage to houses, threatening local communities.

Some of these earthquakes occur very near the fracking site itself, but others have been reported as far as 50 kilometres away, making it difficult to guarantee the safety of surrounding areas.

Geothermal energy requires high-pressure injection of fluid, just like fracking. Credit: US Department of Energy/Energy.gov

The new study, published in  Science , takes a significant step forward in understanding this phenomenon. Experimenting in shallow geological faults, the researchers found that pumping water into these areas caused the rock along the fault lines to slowly slip. These "silent" movements didn't produce earthquakes at the initial point of slippage, but gradually increased the pressure on more distant parts of the faults, inducing earthquakes much further away from the borehole than the injected fluid could reach.

The research shows that by this mechanism, fracking can induce earthquakes tens of kilometres away. In Oklahoma, where fracking is an established practice, millions are at risk from property damage.

This, of course, is not good news – but the first step in assessing whether a problem can be solved is understanding it. Setting the wider debate over the legitimacy of fracking to one side, the results are an important step forward in determining whether the key safety concern with fracking can be resolved.

FULL SOURCE ARTICLE ABOUT FRACKING EARTHQUAKES

by Gillian Foulger, The Conversation

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Taxonomy

• Fracking
• Hydraulic Fracturing Fluids
• Fracking Technology