Fracking could cause large, worldwide earthquakes, say scientists

Wastewater injection can cause earthquakes and tremors in regions that do not usually experience them, suggests a new study. The use of water injection within industries such as oil and natural gas drilling and at geothermal plants has been linked to seismic activity in previous studies. Scientists now claim that earthquakes in other areas of the world can result in tremors or quakes at the point of water injection.

Studies from around 50 years ago show that the injection of water into the ground at high pressure - as is done through the process of hydraulic fracturing (fracking) - has the ability to increase the amount of pressure on seismic faults. This pressure can mount and make the faults more likely to slip, which results in tremors or an 'induced' earthquake.

The new research, by geologists at Columbia University, has found that the process could have the ability to result in larger earthquakes due to the increase in fluid pressure. The study also suggests that the weakened seismic faults could be at risk from being triggered by activity elsewhere in the world, due to the movements of seismic waves. This phenomenon was originally believed to be a natural cause of events, but the research suggests that it is not always the case.

The scientists, whose findings were published in the journal Science, examined the seismic records related to three areas that use wastewater injection. The records of Oklahoma, Texas and Colorado were examined for evidence of small earthquakes, which were compared to the records relating to larger earthquakes throughout the world. A pattern was discovered between the smaller earthquakes throughout the US states and earthquakes of magnitude 3 or higher in other areas of the world.  

With the discovery of this relationship between tremors triggered by water injection and larger worldwide earthquakes comes the worry that increased levels of fluid pressure - created by the increased drive in many countries to extract natural gas through fracking - could affect underground faults that as yet have not been related to earthquakes. These inactive faults could end up being triggered by distant fracking activity, which may result in a series of larger earthquakes at increased magnitudes.