The following is a weekly news article from “Earthweek: A Diary of the Planet,” which is a featured page on the UCSB Geography web site:
“In 2011, a 5.6 magnitude quake apparently caused by an injection well struck central Oklahoma, injuring several people and damaging more than a dozen homes. The deep injection into the ground of wastewater byproducts from hydraulic fracturing, or fracking, has caused a significant increase in U.S. earthquakes since the practice has recently become more widespread.
The U.S. Geological Survey (USGS) reports that there were more than 300 earthquakes above magnitude 3.0 from 2010 to 2012, which is a five-fold increase from the average number of 21 tremors per year measured from 1967 to 2000. There are now more than 30,000 deep disposal wells in the country, typically injecting leftover fluids from fracking wells used for natural gas extraction. And while the actual practice of fracking has not been found to cause any significant seismic events, the far deeper injecting of wastewater from the practice has.
Sometimes the water is blasted into deep, dormant faults. USGS geologist William Ellsworth says that even faults that have not moved for millions of years can be made to slip if conditions are right. But he points out that only a few of the approximately 30,000 wastewater wells appear to have caused the increase in tremors. Columbia University scientists caution that powerful earthquakes thousands of miles away can trigger swarms of minor quakes near injection wells as the arriving seismic waves help release the local built-up pressure.”
Editor’s note: See the original USGS Science Feature by William Ellsworth et al., “Man-Made Earthquakes,” here. For more on the subject, see the Geological Society of America’s article, “Potentially induced earthquakes in Oklahoma, USA: Links between wastewater injection and the 2011 magnitude 5.7 earthquake” here.
