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Research & Commentary: As Oklahoma Oil Production Climbs, Seismic Activity Falls

May 17, 2019

Earthquakes Have Decreased 83 Percent Between 2015 And 2018

Recently updated data from the U.S. Geological Survey (USGS) shows seismic activity in Oklahoma has declined rapidly since 2015, when lawmakers reduced the volume in wastewater disposal wells. Over the same period, Oklahoma oil production has increased substantially.

In June 2015, seismic activity in the Sooner State reached a peak of 887 earthquakes of a magnitude-2.8 (M2.8) or greater. By June 2018, the number of earthquakes decreased by 83 percent, to 154 M2.8 quakes. Over this same period, oil production in Oklahoma is up 20 percent and rigs have increased by13 percent. M2.8 is roughly the threshold needed to feel an earthquake on the surface. M3.0 earthquakes produce “vibrations similar to the passing of a truck,” according to the USGS.

While Oklahoma has a long history of seismicity, the state had seen a significant increase in the number of earthquakes between 2013 and 2015. This spate of earthquakes led to public confusion as to whether hydraulic fracturing, commonly called “fracking,” was the direct cause of these earthquakes. Some state lawmakers even called for an outright moratorium on fracking in Oklahoma in 2015. The problem did not stem from fracking activity, but from the wastewater disposal wells, and this problem seems to have been mitigated by the actions of state regulators and the oil industry.

Wastewater injection and disposal wells are shafts in which brine (salt water) and other fluids are re-injected so drillers can dispose of them. While wastewater is produced by fracking operations, it is also produced in almost all other more traditional oil and gas drilling and production processes. It is not the drilling itself that is potentially causing tremors, nor is this a problem exclusive to fracking. Wastewater disposal involves much higher injection pressures and volumes of fluid than fracking, because the aim of drillers is to keep those fluids in well reservoirs. The practice, by law, is overseen by local or regional Environmental Protection Agency (EPA) officers. Extrapolating that fracking is the cause of these earthquakes because frack wastewater is occasionally injected is comparable to saying turning on the ignition of a car causes traffic accidents.

In a major study, the EPA 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 Oklahoma Geological Survey analysis released in October 2017 found only 282 of 23,000 measurable earthquakes in Oklahoma from 2011 to 2016 occurred within two kilometers of a fracking well within a week of the well’s stimulation.

As the USGS notes on its “Myths and Misconceptions” webpage, fracking is not the primary cause of induced (human-caused) earthquakes. The page directly states, “Fracking is NOT causing most of the induced earthquakes.”

A database administered by researchers at the United Kingdom’s University of Durham and University of Newcastle upon Tyne is the largest and most up-to-date database of earthquake sequences purported to have been induced or triggered by human activity worldwide since the 1800s. According to this important database, fracking has been conclusively linked to only 6 percent of all human-caused earthquakes, 46 earthquakes overall. Considering there are at least 1.1 million active fracking wells in the United States, this number is miniscule. In Oklahoma, only three earthquakes have been conclusively linked to fracking.

“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,” writes 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.

Debunking Four Persistent Myths about Hydraulic Fracturing
This Heartland Institute Policy Brief by Policy Analyst Timothy Benson and Linnea Lueken, a former Heartland communications intern, outlines the basic elements of the fracking process and then refutes the four most widespread fracking myths, providing lawmakers and the public with the research and data they need to make informed decisions about hydraulic fracturing.

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 6 percent, or just 44 earthquakes overall, as of May 2019. 

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.

Climate Change Reconsidered II: Fossil Fuels – Summary for Policymakers
In this fifth volume of the Climate Change Reconsidered series, 117 scientists, economists, and other experts assess the costs and benefits of the use of fossil fuels1 by reviewing scientific and economic literature on organic chemistry, climate science, public health, economic history, human security, and theoretical studies based on integrated assessment models (IAMs) and cost-benefit analysis (CBA).

The Social Benefits of Fossil Fuels
This Heartland Policy Brief by Joseph Bast and Peter Ferrara documents the many benefits from the historic and still ongoing use of fossil fuels. Fossil fuels are lifting billions of people out of poverty, reducing all the negative effects of poverty on human health, and vastly improving human well-being and safety by powering labor-saving and life-protecting technologies, such as air conditioning, modern medicine, and cars and trucks. They are dramatically increasing the quantity of food humans produce and improving the reliability of the food supply, directly benefiting human health. Further, fossil fuel emissions are possibly contributing to a “Greening of the Earth,” benefiting all the plants and wildlife on the planet.

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.

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.

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.


Nothing in this Research & Commentary is intended to influence the passage of legislation, and it does not necessarily represent the views of The Heartland Institute. For further information on this subject, visit Environment & Climate News, The Heartland Institute’s website, and PolicyBot, Heartland’s free online research database.

The Heartland Institute can send an expert to your state to testify or brief your caucus; host an event in your state; or send you further information on a topic. Please don’t hesitate to contact us if we can be of assistance! If you have any questions or comments, contact Lennie Jarratt, a state government relations manager at The Heartland Institute, at or 312/377-4000.

Tim Benson joined The Heartland Institute in September 2015 as a policy analyst in the Government Relations Department. @BenceAthwart