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
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?
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
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?