The U.S. Geological Survey released maps showing areas in the central and eastern U.S. at risk for potential ground shaking in 2017 due to human activity and natural earthquakes.
Around four million people live and work in the areas most likely to experience ground shaking this year, according to the USGS.
The majority of the people at risk are living in Oklahoma and southern Kansas, areas with a higher chance of induced seismicity. Around half a million people are also at risk from shaking due to natural earthquakes.
The 2017 report forecasts less ground shaking than last year because fewer earthquakes occurred in 2016 than in 2015.
The USGS speculated that the decrease may be due to less wastewater injection, which is a result of regulatory actions, and a decrease in oil and gas production due to lower prices.
The chance of earthquake hazards fluctuates depending on the policy and industry landscape of the time, according to USGS National Seismic Hazard Mapping Project Chief Mark Petersen.
“The forecast for induced and natural earthquakes in 2017 is hundreds of times higher than before induced seismicity rates rapidly increased around 2008,” Petersen says. “Millions still face a significant chance of experiencing damaging earthquakes, and this could increase or decrease with industry practices, which are difficult to anticipate.”
Induced earthquakes are triggered by wastewater disposal, which involves injecting wastewater from oil and gas production into deep underground wells. The wells cause pressure changes that weaken faults. The USGS notes that most injection wells do not trigger earthquakes, suggesting a number of factors contribute to the likelihood of ground shaking.
Despite the overall decrease in earthquakes last year, Oklahoma recorded the highest number of large earthquakes in its history, including the largest earthquake ever recorded in the state.
This research was published March 1 in Seismological Research Letters.
People living in areas at risk of ground shaking can learn more about staying prepared for earthquakes here.
View all of the USGS regional and national maps.
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