Research & Commentary: USGS Forecast Notes ‘Rapid’ Decrease in Oklahoma Earthquakes

Published May 16, 2018

The U.S. Geological Survey’s (USGS) latest annual forecast for induced and natural seismicity for the central United States concludes the number of magnitude-3.0 (M3) and greater earthquakes on the moment magnitude scale, which measures the strength of earthquakes, have been declining rapidly in Oklahoma since 2015, when lawmakers reduced the volume in wastewater disposal wells.

“Rates of earthquakes across the United States M≥3.0 grew rapidly between 2008 and 2015 but have steadily declined over the past 3 years, especially in areas of Oklahoma and southern Kansas where fluid injection has decreased,” the forecast notes. USGS forecasts the Sooner State’s seismicity risk levels will remain “elevated” for the coming year. However, USGS notes the chances of a large earthquake in Oklahoma are small.

“The short‐term hazard levels for Oklahoma are similar to short‐term hazard calculated in the more seismically active regions of California. This does not imply the long‐term hazard in California and Oklahoma are the same,” USGS stated. “California has historically experienced many large and great (M∼8.0) earthquakes that have caused extensive damage. Historically, Oklahoma has not experienced earthquakes greater than M 5.8, and although it is possible that larger earthquakes could be generated by ruptures that link across multiple faults in tectonically active regions … this has not been observed in Oklahoma. Larger earthquakes in Oklahoma only have a small chance of occurrence in our model.”

While Oklahoma has a long history of seismicity, the state has seen a significant increase in the number of earthquakes since 2013. This spate of earthquakes has led to public confusion as to whether hydraulic fracturing, commonly called “fracking,” is the direct cause of these earthquakes. Some state lawmakers even called for an outright moratorium on fracking in Oklahoma in 2015. 

However, an Energy in Depth analysis of USGS data found the daily average of felt earthquakes – those higher than M2.8 – was 79 percent lower in the first three months of 2018 than in 2015, and 27 percent below those experienced in 2017. An earlier analysis of monthly USGS data by Energy in Depth concluded the amount of monthly earthquakes in Oklahoma has decreased 86 percent from its peak in June 2015.

In a major study, the Environmental Protection Agency concluded most injection wells do not cause earthquakes and “very few” earthquakes produced by those that do can be felt by humans. Another study, published in Science in 2014, found only four of the roughly 4,500 injection wells in Oklahoma had most likely induced seismic activity, while an OGS analysis released in October 2017 found only 282 of 23,000 measurable earthquakes in Oklahoma between 2011 and 2016 occurred within two kilometers of a fracking well within a week of the well’s stimulation.

“Oklahoma regulators have implemented measures that have either shut in or reduced volumes of injection in roughly 700 disposal wells, reducing wastewater injection volumes 40 percent from 2014 levels,” wrote Energy in Depth’s Seth Whitehead. “Though these more than a dozen directives — which included increased monitoring, well plugging, and volume reductions for hundreds of injection sites near seismic events — have resulted in a ‘significant economic impact,’ they have been largely supported by industry and have proven effective.”

Sensible precautions such as those taken in Oklahoma can reduce the risk of increased induced seismicity. In many cases these precautions are already being taken by drillers without any government mandates. Flatly, concerns about induced seismicity are overblown and do not provide justification for banning fracking or over-regulating it out of existence.

The following documents provide more information about hydraulic fracturing and induced seismicity.

Fracking Facts: The Science, Economics, and Legal Realities
Hydraulic fracturing, commonly known as fracking, has been employed in the United States since the 1940s. Although innovation has improved the precision of the process, the essentials are the same. Utilizing horizontal drilling, a mixture of mostly water, sand, and trace amounts of chemicals, are used to create fissures in underground shale deposits to allow oil and natural gas trapped in hard rock to move toward the surface to be collected. Activists have blamed fracking and the processes associated with it for emissions of pollutants, earthquakes, and even groundwater contamination, though independent evidence consistently shows these allegations to be false. Leigh Thompson of the Texas Public Policy Foundation argues the evidence supporting fracking bans looks slim when attention is drawn to the facts.

Fracking and Earthquakes
Fracking is responsible for some of the greatest growth in oil and gas production the United States has ever experienced. Yet, as U.S. energy extraction increases, so have concerns about the safety of fracking, with The New York Times linking the practice to “Scores of earthquakes.” Research shows, however, the risk of earthquakes caused by fracking is minimal and can be fixed with modest siting regulations, bonding requirements, and wastewater recycling. Jillian Melchoir of the Independent Women’s Forum writes that it is essential to understand what the science is actually revealing about energy extraction and induced seismicity and to create balanced public policy that allows safe energy extraction to continue.

Injection Wells and Earthquakes: Quantifying the Risks
This report from StatesFirst, a partnership between the Ground Water Protection Council and the Interstate Oil and Gas Compact Commission, states data from the U.S. Geological Survey and several peer-reviewed studies show out of an estimated 40,000 disposal wells across the United States, only 218 of them have been linked to or suspected of being a possible cause of seismicity. This means only 0.15 percent of all Class II injection wells and 0.55 percent of all federally regulated disposal wells in the United States have been tangentially associated with a seismic event of any size.

The Human-Induced Earthquake Database
This database, administered by researchers at the University of Durham and the University of Newcastle upon Tyne in the United Kingdom, is the largest and most up-to-date database of earthquake sequences proposed to have been induced or triggered by human activity since the 1800s. Of these, fracking has been conclusively linked to only 4 percent, or just 29 earthquakes overall, as of July 2017. 

Bette Grande: Fracking and Earthquake Misconceptions
In this edition of the Heartland Daily Podcast, Research Fellow Isaac Orr and Research Fellow Bette Grande discuss earthquakes and their relationship with hydraulic fracturing. Grande also gives the listeners an inside look at the state of oil production in North Dakota in the wake of falling oil prices. 

Impacts of the Natural Gas and Oil Industry on the U.S. Economy in 2015
This study, conducted by PricewaterhouseCoopers and commissioned by the American Petroleum Institute, shows that the natural gas and oil industry supported 10.3 million U.S. jobs in 2015. According to the Bureau of Labor Statistics, the average wage paid by the natural gas and oil industry, excluding retail station jobs, was $101,181 in 2016, which is nearly 90 percent more than the national average. The study also shows the natural gas and oil industry has had widespread impacts in each of the 50 states.

The Local Economic and Welfare Consequences of Hydraulic Fracturing
This comprehensive study published by the National Bureau of Economic Research says fracking brings, on average, $1,300 to $1,900 in annual benefits to local households, including a 7 percent increase in average income, a 10 percent increase in employment, and a 6 percent increase in housing prices.

What If … Hydraulic Fracturing Was Banned?
This study is the fourth in a series of studies produced by the U.S. Chamber of Commerce’s Institute for 21st Century Energy. It examines what a nationwide ban on hydraulic fracturing would entail. The report’s authors found by 2022, a ban would cause 14.8 million jobs to “evaporate,” almost double gasoline and electricity prices, and increase natural gas prices by 400 percent. Moreover, cost of living expenses would increase by nearly $4,000 per family, household incomes would be reduced by $873 billion, and GDP would be reduced by $1.6 trillion.

What If … America’s Energy Renaissance Never Happened?
This report by the U.S. Chamber of Commerce’s Institute for 21st Century Energy examines the impact the development of shale oil and gas has had on the United States. The report’s authors found that without the fracking-related “energy renaissance,” 4.3 million jobs in the United States may not have ever been created and $548 billion in annual GDP would have been lost since 2009. The report also found electricity prices would be 31 percent higher and gasoline prices 43 percent higher.


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