Scientists have directly linked oil and methane production practices in the southwestern U.S. to the growing number of earthquakes in Colorado and New Mexico over the past 13 years. A new study released the U.S. Geological Survey (USGS) found that the Raton Basin had little to no seismic activity prior to 1999. Between 1972 and 2001, there was only one earthquake of any significance.
From 2001, the basin — which stretches from southern Colorado to northern New Mexico — has seen 12 earthquakes greater than 3.8 on the Richter scale. The quakes started not long after the deep injection of wastewater from the coal-bed methane fields began.
The statistical probability of such a sharp increase by random natural occurrence is about 3 percent, say the scientists.
“I think the main message is it’s important to monitor the waste water disposal wells and find out early on what the seismic response is likely to be,” said USGS researcher Arthur McGarr in an interview with Colorado’s NBC affiliate .
Injecting wastewater is not fracking, though there is scientific concern over that type of disposal, too.
“We… find that the deep injection of wastewater from the coal-bed methane field is responsible for inducing the majority of the seismicity since 2001,” the reports authors stated in the abstract.
All of the authors of the study, published at the end of September 2014, are scientists who work with the USGS. Their study has detailed lines of evidence that make direct connections between the injection wells and seismic activity in the region.
They said that a magnitude 5.3 earthquake in August 2011 is the most recent seismic event (and second largest) for “which there is clear evidence that the earthquake sequence was induced by fluid injection.”
The earthquakes began in 2001, approximately two years after wastewater fluid injection in the basin from oil and gas production started. Energy companies have been involved in the production of coal-based methane in Colorado since 1994. The wastewater from the production is injected into underground wastewater wells, and is known to have a tendency to raise the pressure in areas surrounding the wells. That pressure can lead to earthquakes.
The study, published in the October 2014 issue of the Bulletin of the Seismological Society of America (BSSA), found that the increased number of earthquakes has been contained to the area of industrial activity and within about 3 miles of wastewater injection wells.
A range of about 1.5 to 3.6 million barrels of wastewater per month have been injected into the basin.
[Photo: Flickr.com]
