Man-made earthquakes, caused by the storage of wastewater in wells, are weaker than naturally occurring quakes of similar magnitude, according to a new study from the U.S. Geological Survey. Fracking has transformed the American energy landscape virtually overnight, but scientists have found a troubling correlation between the storage of wastewater from the controversial drilling practice in underground wells and a growing number of small-magnitude earthquakes.Scientists have hypothesized that the weight of this water puts stress on faults, causing micro-quakes by the dozens. These earthquakes are of a much smaller magnitude than the kinds that make headline news, typically somewhere in the 3–4 magnitude range. According to new research, they actually seem to shake less than their natural counterparts. The AP reports:
The way artificial quakes felt was equivalent on average to a natural quake that had a magnitude 0.8 smaller. So a 4.8 induced quake felt like a 4.0 quake, [study author and U.S. Geological Survey geophysicist Susan Hough] said. The magnitude scale used by USGS and others is mathematically complex, but a drop in 0.8 magnitude translates to about 16 times less strength or energy released. […]The artificial quakes may have less energy — only after 6 miles away — because the fault is lubricated by the injected wastewater, making it easier to slip and do so more smoothly in less of a herky-jerky motion, Hough theorized. Also these faults can be slipping with less pent-up energy than they would have if they slipped naturally years later. […]“The hazard of these earthquakes is lower than what you’d expect,” Hough said. “It’s not that there’s no hazard, it’s just that it’s a little better than you might think.”
We’ve covered this issue in the past (if you’re interested, read more in parts one, two, and three of this series), and understand the gravity of this side effect of fracking. That these earthquakes might be less serious than feared—possibly because, as the study’s author posited, the stored wastewater lubricates the faults, and relieves tension before it can build up to something more serious—should be seen as very good news, if still preliminary at this point.But just because these earthquakes might be less serious than previously thought doesn’t mean they should be written off entirely. Storing wastewater in wells isn’t the best solution for the drilling industry. Recycling it would cut down on the strain fracking puts on water resources, get rid of these earthquakes (however small they might be), and eventually might help drillers’ bottom line, opening up more reserves for further exploration. Companies are already making headway on that front, and as much as we like seeing studies like this most recent one from the USGS, we’d like the industry to continue to make strides of its own.