There are plenty of reasons to worry about fracking—groundwater contamination, methane leaks, that flaming tapwater thing. But can it really cause earthquakes? That's the question the US Geological Survey set out to answer after a spate of tremors in the Midwest—an area not usually known for earthquakes—alerted scientists to the possibility that some of them might be manmade.

So, does fracking cause earthquakes? Not exactly, but the way companies dispose of fracking waste can, which means that other types of energy-related activity that rely on fluid injection—enhanced oil recovery, enhanced geothermal systems, carbon capture and sequestration—also have the potential to cause quakes. Still, the evidence suggests that we can add earthquakes to the growing list of fracking-related hazards, alongside air pollution, tainted drinking water, and potentially outsized carbon emissions.