I WONDER where Tony Kelly (HAS, Oct 22) gets his evidence about fracking from. “There is also the probability of earthquakes.

Minor tremors will be magnified at least ten times when they happen below grossly disturbed strata.”

Living in Crook he ought to be aware that much of County Durham stands on “disturbed strata”. Some villages have had ten or 20 metres of coal taken from underneath them. Surely that is gross disturbance.

Where then is the evidence of earthquakes? Subsidence yes, but no earthquakes. It does Mr Kelly’s cause little good to put forward speculation as fact.

Bill Bartle, Barnard Castle