put it recent earthquakes are quote almost certainly man made and quote and the u.s.g.s. has already linked to nearly fifty recent earthquakes in oklahoma just in that one state underground fracking so knowing what we know now about fracking earthquakes should we continue to let energy companies punch holes deep underground risking more tremors dr tony in graphene joins me now he is the see professor of engineering at cornell university dr graff you welcome you to be back with you tom thank you for coming back on the program he first explain the process of fracking and how the u.s.g.s. concludes that it's causing earthquakes. sure fracking is the injection. manmade blewitt usually water based also containing other chemicals and sand or ceramic proppant into an underground source of your light natural gas or oil and the purpose of opening existing fractures in that rock or creating new fractures net rock so that it actively becomes more permeable in is it's easier to get the oil or gas out of it so it's a process that the energy industry cause well stimulation isn't fractu