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.
Hydraulic Fracturing in Virginia. Hydraulic Fracturing (also known as âhydrofracking, âfracking,â or âfracingâ) has received considerable public attention due to recent drilling activity in the Marcellus Shale in the Appalachian region, the Barnett Shale in Texas, and the Bakken Shale in North Dakota and Montana.