ROCKY MOUNTAIN HOUSE, A.B. – A second earthquake in less than a week shook central Alberta on Sunday, although a seismologist notes it occurred in a different geologic region than a quake last week that’s been linked to fracking.
Honn Kao with the Geological Survey of Canada says the 4.4 magnitude quake was detected at around 4 a.m., with an epicentre about 32 kilometres northwest of Rocky Mountain House.
Kao says no damage has been reported, although he says many people who live in the area have reported feeling it, one as far away as Edmonton.
A 4.6 magnitude earthquake last Monday that was felt in the communities of Red Deer and Sylvan Lake has prompted the Alberta Energy Regulator to order a company to suspend fracking operations at a well site.
Kao notes that while the two quakes were geographically close, Sunday’s quake happened in the Rocky Mountains geological system, whereas last week’s event occurred in the Western Canadian Sedimentary Basin.
Cara Tobin, a spokeswoman for the AER, says there doesn’t appear to have been any industrial activity in the area of the most recent earthquake, but staff will be checking the data to make sure.
“As inactive as Alberta is tectonically, this area is comparatively active, and so we do see more seismic activity in that area than we do in other areas,” Tobin said of the region where Sunday’s earthquake occurred.
In August 2014, a 4.3 magnitude earthquake occurred in the same region. It didn’t do any damage but power was disrupted to about 500 customers, including a gas plant near Rocky Mountain House.
Following last week’s quake, the AER said Vesta Energy Ltd. must suspend hydraulic fracturing operations at its well site, and must submit a report of all seismic activity in the area since April, as well as specific fracturing data for the well site from Jan. 29 to March 4.
The regulator has also ordered Vesta to file a plan to eliminate or reduce future seismic activity from fracturing.
Hydraulic fracturing involves pumping chemicals and sand underground to break up rocks to help get oil and natural gas flowing.
Kao said some of the people who felt Sunday’s quake reported they were woken up by the shaking.
He said more analysis will be needed to say definitively that the two quakes weren’t linked, but at the moment there doesn’t appear to be any evidence of it.
“If there is no active injection operation nearby then certainly we will consider this to be a natural tectonic earthquake,” Kao said.