On Saturday, Sept. 3, Oklahoma experienced a 5.8 magnitude earthquake, its largest temblor on record. And since then Oklahoma has experienced more than 10 others. Since 2011, the number of earthquakes has increased by 5,000 percent.
Is this normal for Oklahoma? Well, it’s becoming so. In fact, Oklahoma is becoming as prone to earthquakes as California–in 2014, Oklahoma displaced California as second with most earthquakes in a year to Alaska.
But now the question is why? Why are parts of Oklahoma getting more earthquakes? Contrary to popular belief and rumors, it is not fracking. Not exactly, at least. It is wastewater disposal wells, wells that inject fluid deep underground in rock formations of sandstone or limestone.
So what is fracking and what is wastewater? Fracking (hydraulic fracturing) is a method of extracting natural gas, which can be manufactured into a fuel source, by pumping more than a million gallons of water, sand and chemicals underground at high pressure, cracking the rock layer and releasing the gas. Afterwards, all the water, sand and chemicals pumped underground have be to removed, creating wastewater, which is then injected back underground into a wastewater disposal well.
So why are wastewater disposal wells suspected of inducing earthquakes? Because wastewater is being pumped into untouched rock which creates a higher pressure underground, increasing the likelihood of induced earthquakes. As of 2015, there were nearly 3,200 active disposal wells in Oklahoma. Immediately following the Sept. 3 earthquake, officials took to shut down 67 of the wells in 1,100 square miles.
But the latest discovery? A new fault line, an area where there has been significant displacement of rock underground, and when energy is released, causes earthquakes. Upon discovery, officials ordered 32 more wells to be shut down, as they were deemed too close to the fault line.
To read more about Oklahoma and its earthquakes, please visit earthquakes.ok.gov.
To learn about health issues related to earthquakes, please visit the Disaster Information Management Research Center website.
–Written by Sara Goodwin, NN/LM SCR