Protests against proposed fracking operations in southern England culminated today with the arrest of Caroline Lucas, a Green Party member of parliament. Meanwhile, new geophysical research concludes that over 100 small earthquakes were triggered in a single year of fracking-related activities in one region of Ohio.

Lucas was one of about six demonstrators arrested for refusing to move from a sit-down protest when asked by police. The protest, which involved hundreds of activists, took place at a site in Balcombe, West Sussex, where a company called Cuadrilla aims to sink a single conventional oil well as a prelude to possible fracking operations. The company stresses that no permission has yet been given for fracking itself.

The Ohio quakes, centred around Youngstown, were triggered by the disposal of wastewater from fracking operations in the neighbouring state of Pennsylvania rather than by the fracking process itself.

The new geophysical research, by Won-Young Kim at Columbia University in Palisades, New York, is the latest to suggest that the main risk of earthquakes associated with fracking relates to the way the water used in the operations is disposed of afterwards. In Ohio, the wastewater was injected into a deep well. This raised the pressure of water within the rock and triggered 109 small quakes between January 2011 and February 2012. The largest, on 31 December 2011, had a magnitude of 3.9.


Cause and effect

Seismologist Brian Baptie at the British Geological Survey (BGS) says that very few quakes are caused by the actual hydraulic fracturing process. The only known examples occurred in Blackpool, UK, in 2011, and in the Horn River Basin of western Canada between 2009 and 2011.

Quakes are not the only reason that fracking is such a controversial technology. There are also concerns that the chemicals added to fracking water to aid the process may contaminate groundwater reservoirs – although geologists at the BGS say that groundwater reservoirs usually lie thousands of metres above the rocks that are fracked in well-managed operations, making contamination unlikely. They acknowledge, however, that there is little peer-reviewed research into the subject.

A spokesman for Cuadrilla told New Scientist that it had “scaled back” activity in the wake of the current UK protests to avoid any possible dangers to the protesters and the public. As the standoff intensifies, the BGS is continuing a survey to estimate reserves potentially available from oil shale in West Sussex, following a similar survey in England’s midlands, where fracking operations are also proposed.

Journal reference: Journal of Geophysical Research: Solid Earth, DOI: 10.1002/jgrb.50247