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.
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 water can 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.