The deep injection of wastewater underground is responsible for the dramatic rise in the number of earthquakes in Colorado and New Mexico since 2001, according to a study by experts from the US Geological Survey.
The Raton Basin, which stretches from southern Colorado into northern New Mexico, was seismically quiet until shortly after major fluid injection began in 1999.
Since 2001, there have been 16 magnitude earthquakes greater than 3.8 (including 5 and 5.3) compared to only one the previous 30 years.
The increase in earthquakes is limited to the area of industrial activity and within 5 kms of wastewater injection wells.
In 1994, energy companies began producing coal-bed methane in Colorado and expanded production to New Mexico in 1999.
Along with the production of methane, there is the production of wastewater, which is injected underground in disposal wells and can raise the pressure in the surrounding area, inducing earthquakes.
Several lines of evidence suggest the earthquakes in the area are directly related to the disposal of wastewater, a by-product of extracting methane, and not to hydraulic fracturing occurring in the area.
Beginning in 2001, the production of methane expanded, with the number of high-volume wastewater disposal wells increasing with 21 presently in Colorado and 7 in New Mexico.
Since mid-2000, the total injection rate across the basin has ranged from 1.5 to 3.6 million barrels per month.
The study, The 2001-Present Induced Earthquake Sequence in the Raton Basin of Northern New Mexico and Southern Colorado, is co-authored by Justin Rubinstein, William Ellsworth, Arthur McGarr and Harley Benz of the US Geological Survey and published the Bulletin of the Seismological Society of America (BSSA).
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