A new study published by the Geological Survey of Canada has found that 90% of all large earthquakes that have occurred in B.C. and Alberta oil and gas patches since 1985 were a result of hydraulic fracking.

In total 39 wells were responsible for 90% of the earthquakes in the region that were magnitude 3.0 or greater. The researchers studied 12,289 hydraulic fracturing wells and 1,000 fracking waste disposal wells and found that 60% of the region’s earthquakes came from the fracturing wells and that 30%-35% can be traced to the disposal wells.

One of the study’s authors commented that this is another part of the risk associated with fracking and that further research is recommended to help policymakers make the right decisions regarding the practice. Another author commented that, while no structural damage has happened, it was only a matter of time.

The study has also confirmed a difference between induced earthquakes in Canada and The States. In Canada the majority of earthquakes are caused in the process of fracking, when high pressure mixture is injected into the ground to release oil. In The States the majority of earthquakes are caused from the disposal of fracking by products in the waste wells.