Mogsie Earthquakes, as you probably know are caused when tectonic plates move and the friction between them causes the ground to shake--both internal and external forces can be responsible for plate movement. Sometime Internal force can build up to a point where the plates would move, but don't because the friction between the 2 is great enough to hold them immovable UNLESS something reduces THAT friction. For example 2 metal plates may not slide along each other because of friction UNLESS a fluid such as oil is placed between the plates which reduces the friction and allows them to move. Same thing with plate tectonics-- add that fluid in this case water pumped under ground at a high rate and/or pressure and it CAN act like oil does on those steel plates and allow the underground Plates to move and cause an earthquake. I say CAN because all conditions have to be just right ( or in this case wrong)for this to happen. If there's no real friction between plates in that area or the wrong subsurface geology or not enough water or not enough water pressure, or, or , or--well you get the point. It is claimed that fracking fluid which incidentally is normally 95% water, disposal waste water, and even high pressure steam when injected underground can act as a lubricant on these subsurface plates and cause an earthquake and I have no reason to doubt them. That said, a lot of variables, like I mentioned above have to line up just right. I work at a Gas Storage Facility for my Pipeline Company right in the middle of the old Loudon Oil Field, Loudons been in continuous oil production since 1937 and tons of fracking and down hole water disposal has been done here and neither my company, nor Exxon (when they were still here) nor any of the Independent oil producers here have EVER caused an Earthquake. Like I said all variables have to be just right so even though it can and does happen during Fracking I suspect its more of a environmentalist and Liberal talking point than a frequent occurrence. As far as Wind Turbines their Ok except when the wind don't blow and Solar Panals are Ok except when the sun don't shine, or when their covered in snow, or when Hail beats the hell out of them. The beauty of COAL AND NATURAL GAS Power Plants is they work 24 hours a day every day as long as they have fuel to burn and since I like to watch T.V. when the sun don't shine and Air Conditioning when the wind don't blow guess where my sympathies lie.