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.
Map: The Fracking Boom, State by State. Fracking now occurs in 21 U.S. states, and could soon begin in five more. This story and infographic were updated on April 28, 2016. As debate intensifies over oil and gas drilling, most states with frackable reserves are already frackingâor making moves to do so in the near future.