by Diarmuid O'Dea
Hydraulic Fracturing or Fracking is a process of drilling into the earth in search of oil or natural gas. Where oil or gas are held in hard rock or shale resevoirs usually at depths of 2,000 feet companies pump a high pressure mixture water and other chemicals to break up the cemented barries and extract the gas or oil. Using Fracking, North American gas and oil producers have been able to increase their share of world oil and gas production. The most recent example of successful fracking is the oil boom in North Dakota.
Fracking causes Earthquakes
The violent process of drilling into the earth and smashing underground gas and oil resvoirs leads some policy experts and scientists to conclude that fracking is causing "felt" earthquakes.Scientists with this point of view have liked fracking activity with earthquakes that coincide with previous unknown fault lines. It's not the fracking per se but fracking in a previously unknown earthquake sensitive zone.
Wastewater Disposal Causes Earthquakes
Other scientists argue that it isn't fracking that causes earthquakes but the closely associated disposal of wastewater back into the earth that casues "felt seismic activity". Salt water is one of the products left over from extracting oil and gas from the earth. The salty brine reamains from pre-historic seas caught in the same underground chambers as oil and gas. The oil and gas industry creates oceans of wastewater and most of it is returned to the earth after production. While a chamber is being filled it creates a constant change in pressure and during that time a seismic event can occur .Usually when the location is filled and capped the new constant pressure does not produce earthquakes.
Fracking and Wastewater Disposal sites are usually nearby so it is understandable that there is a debate about the causes of earthquakesn in the same regions. Earthquakes in areas are definitely increasing. The public is concerened and deserves to know accurately what is causing the increase in activity.
In their 2015 article in Seismological Research Letters, "Myths and Facts on Wastewater Injection, Hydraulic Fracturing, Enhanced Oil Recovery, and Induced Seismicity",
Justin L. Rubinstein and Alireza Babaie Mahani arue that more research is needed and that the most important material needed is : 1) seismic data 2) geological data and 3) industry data.