More than 3 million people in the central United States, the majority in Kansas and Oklahoma, are at risk for human-induced earthquakes this year, the U.S. Geological Survey warned in a new report released Wednesday.
Combined with people at risk for ground-shaking hazards from natural quakes in the same region, the numbers of those in potential quake zones is around 4 million, the USGS said.
Residents in these areas face a significant chance of property damage from induced seismic activity in 2017, the report said.
“The good news is that the overall seismic hazard for this year is lower than in the 2016 forecast, but despite this decrease, there is still a significant likelihood for damaging ground shaking in the CEUS (central U.S.) in the year ahead,” said Mark Petersen, the chief of the USGS National Seismic Hazard Mapping Project.
This year’s forecast is lower than last year because there were fewer significant quakes in 2016 than 2015.
“This may be due to a decrease in wastewater injection resulting from regulatory actions and/or from a decrease in oil and gas production due to lower prices,” the USGS report said.
Some scientists say the quakes result from fracking, which includes a process of collecting wastewater and using high pressure to inject it into deep underground wells, which can ultimately cause dormant faults to shift, according to the USGS.
“The forecast for induced and natural earthquakes in 2017 is hundreds of times higher than before induced seismicity rates rapidly increased around 2008,” Petersen said.
“Millions still face a significant chance of experiencing damaging earthquakes, and this could increase or decrease with industry practices, which are difficult to anticipate.”
This is only the second year that the USGS annual earthquake risk maps have included human-induced quakes. Previous maps only identified hazards from natural earthquakes.