Monday July 7, 2014 0 comments
BOULDER - A new study led by Cornell University with participation from CU-Boulder indicates the massive increase in earthquake activity in central Oklahoma is likely being caused by the injection of vast amounts of wastewater from oil-and-gas operations into underground layers of rock.
In the study, published in the latest issue of Science, researchers used hydrogeological models to determine how much pressure the injected wastewater was building in the pores of underground rocks.
Under high pressure, fluids can seep into existing faults and pry apart the rocks, allowing them to slip past each other more easily and cause earthquakes.
The oil-and-gas industry has been using this process to fracture rock layers - or fracking - to get at trapped oil-and-gas deposits.
"Deciding whether an earthquake is induced or natural is a very difficult process scientifically,' said Matthew Weingarten, a doctoral student in CU-Boulder's Department of Geological Sciences and co-author of the paper.
"The classic way of determining the likelihood of an induced event is by looking at the seismological data alone. We took the next step in determining causation."
Prior to 2008, Oklahoma averaged about two earthquakes each year with a magnitude of 3.0 or greater. This year - between Jan. 1 and May 2 - there have been 145.
The increase coincided with a boom in hydraulic fracking, which generates a large amount of wastewater.
The study was funded in part by the U.S. Geological Service and the National Science Foundation.