As part of our work to better understand areas of induced earthquakes, the USGS installs seismometers in areas of increased seismicity, provides hazard estimations, and uses numerical models.
Increasing Rate of Earthquakes Beginning in 2009
![map of central US and bar graph](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/allCUS.png?itok=u4krIsuH)
The number of earthquakes in the central U.S. has increased dramatically over the past decade. Between the years 1973–2008, there was an average of 25 earthquakes of magnitude three and larger in the central and eastern United States. Since 2009, at least 58 earthquakes of this size have occurred each year, and at least 100 earthquakes of this size every year since 2013. The rate peaked in 2015 with 1010 M3+ earthquakes. Since 2015, earthquake rate has declined. In 2019, 130 M3+ earthquakes occurred in the same region. Nonetheless, this rate is far higher than the average of 25 earthquakes per year. Most of these earthquakes are in the magnitude 3–4 range — large enough to have been felt by many people—yet small enough to rarely cause damage. Damage has been caused by some of the larger events, including the M5.8 Pawnee and M5.0 Cushing Oklahoma earthquakes that occurred in 2016.
This increase in earthquakes prompts two important questions:
- Are they natural, or man-made?
- What should be done in the future as we address the causes and consequences of these events to reduce associated risks?
Observations of static Coulomb stress triggering of the November 2011 M5.7 Oklahoma earthquake sequence
Maximum magnitude earthquakes induced by fluid injection
Probing reservoir-triggered earthquakes in Koyna, India, through scientific deep drilling
The 17 May 2012 M4.8 earthquake near Timpson, East Texas: An event possibly triggered by fluid injection
Modeling earthquake rate changes in Oklahoma and Arkansas: possible signatures of induced seismicity
Injection-induced earthquakes
Potentially induced earthquakes in Oklahoma, USA: links between wastewater injection and the 2011 Mw 5.7 earthquake sequence
Case histories of induced and triggered seismicity: Chapter 40
Investigation of an earthquake swarm near Trinidad, Colorado, August-October 2001
Possible cause for an improbable earthquake: The 1997 MW 4.9 southern Alabama earthquake and hydrocarbon recovery
Triggered earthquakes and deep well activities
Earthquake hazard associated with deep well injection— A report to the U.S. Environmental Protection Agency
As part of our work to better understand areas of induced earthquakes, the USGS installs seismometers in areas of increased seismicity, provides hazard estimations, and uses numerical models.
Increasing Rate of Earthquakes Beginning in 2009
![map of central US and bar graph](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/allCUS.png?itok=u4krIsuH)
The number of earthquakes in the central U.S. has increased dramatically over the past decade. Between the years 1973–2008, there was an average of 25 earthquakes of magnitude three and larger in the central and eastern United States. Since 2009, at least 58 earthquakes of this size have occurred each year, and at least 100 earthquakes of this size every year since 2013. The rate peaked in 2015 with 1010 M3+ earthquakes. Since 2015, earthquake rate has declined. In 2019, 130 M3+ earthquakes occurred in the same region. Nonetheless, this rate is far higher than the average of 25 earthquakes per year. Most of these earthquakes are in the magnitude 3–4 range — large enough to have been felt by many people—yet small enough to rarely cause damage. Damage has been caused by some of the larger events, including the M5.8 Pawnee and M5.0 Cushing Oklahoma earthquakes that occurred in 2016.
This increase in earthquakes prompts two important questions:
- Are they natural, or man-made?
- What should be done in the future as we address the causes and consequences of these events to reduce associated risks?