**Author details**

treatment process. Injecting wastewater into a deep brine aquifer again presents the hazard of

**Figure 11.** Correlation between the number of earthquakes and the volume of fluid injected [26].

Hydraulic fracturing operations cause earthquakes. The USGS has reported a sharp increase in the number of potentially damaging earthquakes, those with a magnitude of three or larger in the Central and Eastern USA due to hydrofracking operation. There has been a 50-fold increase in M3+ quakes from an average of roughly 20 per year to over a

The realization that high-pressure injection of fluids into the deep subsurface can cause earthquakes is not new. In 1967 David Evans, a consulting geologist in Colorado, noted a correlation between injection volumes at a US Army hazardous waste injection well located at the Rocky Mountain Arsenal and earthquake frequency. His figure showing the correlation (**Figure 11**) became a staple of college-level geology textbooks. It was determined that the injection of wastes into the nearly 4000 feet deep well decreased frictional resistance to faulting. "The mechanism by which the fluid injection triggered the earthquakes is the reduction of frictional resistance to faulting, a reduction which occurs with increase in pore pressure" [26]. Disposal of waste fluids by injection into a deep well has triggered earthquakes near

It should be obvious to all readers that the injection of millions of gallons of highly pressurized hydrofracking fluid into each well contributes to the notable increase in induced seismicity reported by the US Geological Survey. Less obvious is the reinjection of brine wastewater that is produced from the formation along with the hydrocarbons after

leakage from improperly cased or grouted wells.

thousand in 2015.

48 Aquifers - Matrix and Fluids

Denver, Colorado [26].

hydrofracking.

Abdullah Faruque1 \* and Joshua Goldowitz2

\*Address all correspondence to: aafite@rit.edu

1 Civil Engineering Technology, Rochester Institute of Technology, New York, USA

2 Environmental Sustainability Health and Safety, Rochester Institute of Technology, New York, USA
