Government scientists, in an unprecedented report, estimate that 7 million Americans are at risk from human-induced earthquakes this year.
The U.S. Geological Survey for the first time included induced seismic activity along with naturally occurring activity in its latest risk maps. The agency also produced its first one-year outlook; USGS scientists previously offered 50-year projections to account for the lifespan of buildings.
“By including human-induced events, our assessment of earthquake hazards has significantly increased in parts of the U.S.,” said USGS project chief Mark Petersen. “This research also shows that much more of the nation faces a significant chance of having damaging earthquakes over the next year, whether natural or human-induced.”
Many areas of the U.S. saw an increase in seismic activity in recent years, which scientists largely attribute to wastewater from oil and gas fracking operations that is injected deep underground.
In the central U.S., the rate of earthquakes in excess of 3.0 in magnitude increased from 24 per year between 1973 and 2008 to 318 per year between 2009 and 2015. Last year alone, the region saw more than 1,000 such earthquakes and 226 occurred through mid-March of this year.
Overall, the USGS identified 21 areas with increased rates of human-induced activity.
The maps showed a 5 to 10 percent chance of a damaging earthquake across a wide swath of central and northern Oklahoma and into Kansas in 2016.
A smaller portion of that area saw a 10 to 12 percent chance, which matched the top projection for a chunk of earthquake-prone California. Oklahoma now experiences more tremors than the Golden State.
The USGS maps also showed lower odds of damaging earthquakes in areas of Arkansas, in the Dallas area and along the Colorado-New Mexico border.
In total, the agency said that 7 million people live or work in those areas, with the majority concentrated in Oklahoma and Texas.
Although areas of Alabama and Ohio also experienced more earthquakes of late, a recent downturn in seismic activity led scientists to leave them off the 2016 projections. Other areas of Alabama and Mississippi with higher recent activity levels remain under investigation.
In addition, although some areas of the western U.S. saw induced earthquakes, USGS officials said that they did not alter their risk due to more frequent naturally occurring earthquakes.
The other significant risk area in the central and eastern U.S. was located near Memphis, home to the New Madrid Seismic Zone.