Residents of California are all too familiar with the uneasy feeling of unstable ground under foot. California, however, is not alone. The Central United States has seen a dramatic increase in human-induced earthquakes activity in recent years.
In 2015, the central United States experienced over a thousand earthquakes measuring 3.0 or larger on the Richter Scale. This record setting amount of earthquakes was 42 times more then the average number of yearly quakes experienced between 1973 to 2008. Oklahoma actually had more earthquakes in 2015 than the historically shaky California.
What is the Cause of all this Increased Earthquake Activity?
Human-induced earthquakes are to blame for the increased seismic activity threatening more than 7 million people in the central and eastern portions of the United States. Human-induced earthquakes are commonly linked with the controversial practice of fracking. Fracking is a process in which water pressure is used to force oil out of previously untapped deposits. The majority of the induced earthquakes, however, are actually the result of the relatively recent industrial process of disposing of contaminated water by injecting the fluids into the ground. The contaminated water is a by-product of all oil and gas extraction and not unique to fracking. The injected wastewater elevates the in-ground fluid pressure increasing the likelihood of fault slippage.
Faults can occur in areas where they haven’t historically been recorded. Normally tectonic stress will hold the faults together, but the injected waste water can essentially push the plates apart.
The increased risk of damaging earthquakes prompted the USGS to include human-induced earthquakes in their hazard forecasts for the first time.
Human-Induced Earthquakes and a Potential for Disaster
Most of the earthquakes are minor but a recent 5.6 magnitude earthquake recently rocked the region near Pawnee, Oklahoma. The earthquake was felt across 6 additional states and is the largest magnitude quake recorded in Oklahoma since 2011. The Federal Emergency Management Agency estimates that a similar sized event hitting a metropolitan area, like the Dallas metroplex, could devastate the city leading to substantial damage, economic loss and potential loss of life.
The 2016 USGS study suggests that the central United States will face a 5-12% chance of damage from additional earthquakes in 2016.