Researchers at the University of Calgary have discovered a precursor to earthquakes caused by hydraulic fracturing, which they say may be able to predict those quakes before they happen.
Hydraulic fracturing — fracking — is the process of injecting a high-pressure mix of water, sand and chemicals into a well to crack apart shale rock and extract natural gas.
What the team of seismologists found is sometimes, fracking can cause layers of rock to slowly slip on a fault — the spot where two tectonic plates come together — eventually putting enough strain on another section of fault to slip suddenly, causing an earthquake.
That means if they can monitor that slowly-creeping slip, it could give seismologists a heads up.
‘Warning time’
“This really gives us a possibility that there could be a way of monitoring that something is going to occur before the actual earthquake occurs,” Thomas Eyre, the study’s lead author said.
T”his slip actually initiates tens of hours before the earthquake occurs. So you’ve got a decent amount of warning time before the earthquake,”
The research appears to explain other laboratory measurements that found earthquakes shouldn’t be happening in shale, the kind of rock where fracking is taking place.
That’s because the quake happens at the part of the fault that’s unstable — which could be hundreds of metres away from the fracking zone.
That’s what happened in the case the researchers studied, when in January 2016 a magnitude 4.1 earthquake was triggered by fracking near Fox Creek in northern Alberta.
“There are existing techniques that are used to try and manage the risk of induced seismicity,” said co-researcher David Eaton.
“What our results indicate is that we might be able to improve on or enhance that monitoring if we could detect this fault creeping effect happening prior to it.”
The team is now hoping to validate their research against other seismic data in the province.
Only a small fraction of fracking wells have been shown to directly trigger earthquakes. But the researchers still say it’s important what factors cause those quakes, and how to prevent them.
“[These] resources belong to all Albertans. So if we’re able to safely and responsibly produce resources without undesired effects like induced seismic events that’s that’s a good thing,” Eaton said.