Fracking causes very low magnitude earthquakes that are rarely felt on the surface. The micro-seismic activity induced by fracking is planned, managed and monitored.
Small magnitude, minor earthquakes are extremely common around the world. In fact, thousands of tiny earthquakes occur naturally every day, but are rarely felt on the surface. Induced seismicity refers to seismic events caused by human activity and is associated with several industrial processes including geothermal energy extraction, mining, dam building and hydraulic fracturing, or fracking.
Micro-seismic events are an intended part of fracking and are planned using extensive scientific research, understanding of geological formations and world-class technology. Vibrations are emitted from the fracking process when fluid is pumped down the oil or gas well to create very small cracks in tight rock formations 2,000 to 4,000 metres underground. That’s a depth equivalent to four CN Towers. The small cracks, or fractures, establish pathways for natural gas or oil to enter the wellbore and be brought to surface.
Fracking-related seismicity is referred to as micro-seismic events because they:
- Measure between -3 and -1 in magnitude on the Richter scale
- Are not felt at surface
- Cause no damage to infrastructure
- Can only be detected with highly sensitive instruments that are deployed close to fracking operations
On the rare occasion, fracking has resulted in a seismic event of magnitude 4 or greater and the vibrations felt at surface are similar to those felt when a large truck passes by. These events are referred to as anomalous induced seismicity as they are unusual or inconsistent with what is expected. In the rare case that anomalous induced seismicity occurs, operations must stop immediately and may not resume until the regulator investigates and provides permission for operations to resume.
Scientific evidence in western Canada indicates that anomalous induced seismicity resulting from fracking has not caused injury or property damage, nor does it pose a risk to public safety or the environment.