USGS Determines that Gas Wastewater Likely Triggered 2011 Quake in Colorado
Posted on Nov 3, 2014 9:17am PST
Underground disposal of wastewater from gas production likely triggered
a moderate earthquake in Colorado in 2011, the U.S. Geological Survey
said on Wednesday in a study that may fuel debate over the impact of the
U.S. energy boom. The finding in the Journal of Geophysical Research is
the latest research suggesting the injection into wells of wastewater
generated by oil and gas extraction can induce earthquakes.
Researchers believe fluids seep into seismic faults and cause them to slip,
triggering temblors. The 2011 magnitude 5.3 earthquake in an oil and gas
basin spanning the Colorado-New Mexico border was felt in nearby Trinidad,
Colorado, where shaking damaged foundations of several homes, said USGS
geophysicist and lead study author Bill Barnhart. The basin, which historically
produced coal, was not known for being especially quake-prone until extraction
of naturally occurring methane gas from coal seams ramped up more than
a decade ago, he said.
“We saw a big increase in seismicity starting in 2001, including
magnitude 5 earthquakes, in many locations in the basin, and that coincided
with a surge in gas production and injection of wastewater,” Barnhart
said. The report bolsters previous studies by U.S. seismologists that
linked wastewater disposal in underground wells with earthquakes in a
handful of states seeing intensified energy production, including Oklahoma
and Texas. The largest was a 5.7-magnitude quake that rattled Prague,
Oklahoma, in November 2011. The southern Colorado temblor just a few months
before was the second largest of such “induced” earthquakes,
Barnhart said.
Such reports have fueled charges by hydraulic fracturing critics that wastewater
disposal tied to fracking, which uses large volumes of water as well as
chemicals to split open rocks and release natural gas, is to blame for
an uptick in quakes. Like previous USGS findings, the new research concentrates
on the role of wastewater injection in triggering quakes rather than extraction
methods, and does not address the wastewater's nature, Barnhart said.
“It's the consensus that wastewater injection is leading to
some of these larger earthquakes. The composition of the fluid might be
a small component, but the fluid itself is the overwhelming factor,” he said.
Scientists suspect the volume of wastewater and how quickly it is injected
may influence seismic activity, but that data is not readily available, he said.