The range of 60-70 decibels sound pressure level is about as loud as normal conversation in 1 meter distance. The distance from the ears to the sound source is very important to the value of the SPL. Scroll down to related links and look at Table of Sound Pressure Levels.
1 Primarily, during the fracking process:  [Earthquakes] were caused by fluid injection during hydraulic fracturing in proximity to pre-existing faults.. 2  Secondarily, via the disposal of fracking wastewater via underground injection.
In addition to water contamination, some worry about the amount of water needed to frack a well. Fracking can also create small earthquakes if done along faults. But the big concern with earthquakes has come with the disposal of used frack water in deep injection wells.