Oklahoma’s Induced Seismicity
Since 2010, Oklahoma has experienced a surge in seismicity. Experts believe this increase is the result of oil and gas wastewater disposal.
Historically, Oklahoma experienced on average 1.5 magnitude three or greater (M3+) earthquakes per year. In 2013, though, the Oklahoma Geological Survey (OGS) observed on average two M3+ per week. Based on increased seismicity rates and geographic trends thereof, OGS concluded these earthquakes were "very unlikely to represent a naturally occurring process" (Andrews 2015).
M3 Oklahoma Earthquakes, 2010-2021
Induced Seismicity
The primary suspected source of this induced seismicity is wastewater injection/disposal associated with oil and gas production.
Image source: KFOR
This water is separated from the oil and gas and injected into disposal wells, often at greater depths from which it was extracted.
Image source: USGS
The greatest concentration of recent seismic activity in Oklahoma follows oil and gas plays characterized by large amounts of produced water. As wastewater injection volumes increase, a concurrent, but time-delayed (weeks to a year or more) increase in seismicity occurs.
Image source: Oklahoma Geological Survey
The Evidence Supporting Induced Seismicity
An OGS report (Andrews 2015) following this increased seismicity found that the seismicity rate in Oklahoma in 2013 was 70 times greater than background seismicity observed in 2008. By 2015, this rate increased to 600 times greater than the background seismicity rate. Additionally, the majority of earthquakes in central and north-central Oklahoma occurred as so-called earthquake swarms rather than as the typical foreshock-mainshock-aftershock sequence of naturally occurring earthquakes. Based on these and other observations, OGS stated it is very unlikely these earthquakes are the result of a natural process.
Before and After 2010
Oklahoma M3+ Earthquakes 1971 to 2009 and 2010 to 2021.
Increased Monitoring
Prior to 1961, earthquakes in Oklahoma were documented by seismic monitoring equipment in neighboring and states and oral accounts. The first seismography in the state was setup in 1961 at the Leonard Geophysical Observatory in Leonard, OK. In 1977, funded by a grant from the Nuclear Regulatory Commission, OGS established a network of remote seismographs. From 1976 to 2010, there were approximately 8 permanent seismic monitoring stations in the state. Today, there are over 90 monitoring stations, both temporary and permanent, in the state.
Seismicity Monitoring Network Stations
Oklahoma Seismicity Monitoring Network
The Oklahoma Geological Survey is currently developing a free and accessible public data viewer for Oklahoma’s geoscience and natural resource data. Currently in a beta release, the viewer will eventually synthesize information on Oklahoma’s oil and gas production, digital images of OGS core and data holdings, OGS and related research publications, and other information. Follow the link below to access the application.
OGS Online Map Portal
