According to a new report from the National Research Council, the controversial practice of hydraulic fracturing — otherwise known as fracking — can cause earthquakes, though the chances of it happening are pretty slim. The report describes fracking as "low risk" when it comes to creating seismic activity that can actually be felt by people, and found that the biggest issue isn't cracking shale rock to extract gas, but injecting the left over wastewater underground to dispose of it. This process is also used during conventional oil and gas production. Further research is needed, but the report reveals that "the total balance of fluid introduced or removed underground" is the biggest determining factor when it comes to inducing earthquakes. The authors of the report believe that the best course of action is for the industry to work together to develop a set of "best practices" designed to maintain that balance.