Wastewater injection depth and Oklahoma earthquakes could be linked: suggests study

Yet another earthquake of 2.8 magnitude hit Alva on 28th January which is located about 31 kilometers from Oklahoma. In the recent years, Oklahoma and adjoining areas have seen a rise in the frequency of earthquakes and scientists estimate this is because of the wastewater injection wells that are spread all over the area. Oklahoma houses more than 10,000 such wells that let out waste water from different factories.

The study suggests that the greater the depth of these injection wells, the higher the magnitude and frequency of the earthquake in the area. Researchers from the University of Bristol have found that state of Oklahoma has become a centre for seismic activities due to the actions of the well operators. In the year 2016, Pawnee experienced an earthquake of magnitude 5.8 which was really devastating for the economy as well as life of the residents.

These earthquakes pose a major threat to infrastructures that could be a national threat like the oil storage factory which upon impact could harm a lot of lives and result in economical loss for the state. The scientists recorded about 800 times increase in frequency of earthquakes occurring in the area after the year 2011 which is a significantly high number. This is because the well operators at Oklahoma have constantly injected about 2.3 billion barrels fluids each year into the base of ground at a depth of 1 to 2 kilometers which is way below the actual level of fresh water supply in the ground. Apart from this, operators inject saltwater at a deeper level to obtain oil and gas.

The scientists have suggested the drilling for gas and oil should not go beyond the range of 600 feet to 1500 feet. This is where the hard rocks are located which is made up of igneous and metamorphic rocks that stabilize the upper softer levels. This particular region is actually filled with many criss cross of faulty zones for earthquake to occur. The closer these wells reach the fault lines, the higher the chances of an earthquake of high magnitude. It’s like forcing your way through a crack in the basement of a building which could potentially bring down the whole building.

The lab experiments conducted by the scientists suggest that forcing in water into these faulty areas weaken their bond and thus lead to an inevitable earthquake, explained the co-author of the study, Thomas Gernon, a Geologist from the University of Southampton. Scientists also stated that the depth as well as volume of the waste water being injection into the ground jointly affects the intensity of an earthquake. The key to reducing the number and magnitude of these earthquakes is to limit the depth a certain distance that should be way above the basement rocks.