Frequently we find ourselves in conversation with fracking deniers who seem certain that the fracking related earthquakes around the world ( some as high as 3.5 on the Richter scale ) are of no consequence. They also seem coincidentally, to be the same people who would not mind a 50m derrick in their back garden nor the noise from the horrendous logistics involved. Of course, they almost always turn out to be people who have not seen GASLAND or other documentaries either.
Here, for general consumption is some official data from the USA. If you read nothing else, do have a look at Fig.9 in the attached pdf document. Beggars belief. http://smu.edu/newsinfo/pdf-files/earthquake-study-10march2010.pdf