Do the UK’s fracking miniquakes matter?

By Zach Boren – Unearthed: There have been 34 tremors in the Blackpool area since Cuadrilla began fracking at nearby Preston New Road three weeks ago, according to data from the British Geological Survey. All of these seismic events have been imperceptible on the surface. This begs the question: do they even matter?

 

From the driller’s perspective, they absolutely do. Any tremor over 0.5ML [local magnitude] on the richter scale requires fracking to stop and testing and monitoring to commence.

So far Cuadrilla has been given the so-called ‘red light’ twice, for a 0.8 quake a fortnight ago and a 1.1 seismic event last week. The company’s CEO has since called for the standards to be relaxed, claiming they are ‘strangling’ the industry.

For local people, however, the answer is less obvious. If they don’t feel the quake, should they care?

 

 

The 0.5 threshold

The traffic-light-system was brought in by the coalition government in 2014 in response to the 2011 Lancashire earthquake widely-attributed to Cuadrilla’s fracking operations, one which was felt at ground level.

The system put in place a series of checks to ensure seismicity is monitored and requires drilling to stop for 18 hours in the event of tremor that exceeds 0.5ML, a standard recommended to government by three leading British geologists in a 2012 government-commissioned report.

The Preese Hall paper said the 1.7 threshold initially proposed was “undesirably high from the viewpoint of prudent conduct of future operations,” and that if it were in place it would mean “no action would have been taken before the magnitude 2.3” quake that Cuadrilla’s fracking operations triggered in 2011 since there hadn’t been a tremor larger than 1.7 in the weeks leading up.

Ed Davey, energy secretary at the time the policy was put in place, told Unearthed: “This was a key decision – based on the best science available – and after extensive consultation. Indeed, I insisted on consulting on the report itself and its recommendations to promote as much transparency as possible.”

Professor Peter Styles, one of the authors of the Preese Hall paper, told Unearthed: “The 0.5ML is a significant level as evidence from around the world shows that it is above that when we see the start of stimulation of movement of small (initially) faults and induced earthquakes which tend to increase in magnitude as more of the fault (or more faults) become involved. That is why we recommended fracking halt for further appraisal at that level.”

But fracking’s years-long interval has complicated matters: “Our original traffic light system then had a sequence of scenarios which might have permitted recommencement of fracking activities until a higher level of 1.0ML and then possibly if not very likely to 1.5ML. The current simplistic TLS which DECC selected has no plan built into it as to what to do next and so we see a sequence of stopping at 0.5ML, restarting after 18 hours and then stopping again etc etc.

“It should also be recognised that the initial traffic light system was devised 7 years ago when there was anticipation that there would be more wells drilled and fracked in the nearish future so that we (or someone else) could reevaluate the situation and perhaps modify the recommendation.”

 

 

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