For years, scientists have waffled over whether hydraulic fracturing–otherwise known as “fracking“–can trigger earthquakes. Last year, a series of earthquakes in Ohio were definitively linked to the practice of pumping wastewater underground after gas and oil have been extracted. In that instance, the fracking was happening nearby. But a study published in the journal Science says that fracking can leave sites vulnerable to tremors triggered by big earthquakes in other parts of the world.
Columbia University scientists studied a handful of fracking sites where far-off earthquakes appeared to have caused tremors. Among them: injection wells in Colorado and Texas that were set off by earthquakes in Japan (2011) and Sumatra (2012) and a mid-sized quake at a drilling site in Oklahoma that occurred a day after the big Chile earthquake in 2010.
Here’s some of what they found, according to Columbia University:
The 2010 Chile quake also set off a swarm of earthquakes on the Colorado-New Mexico border, in Trinidad, near wells where wastewater used to extract methane from coal beds had been injected, the study says. The swarm was followed more than a year later, on Aug. 22 2011, by a magnitude 5.3 quake that damaged dozens of buildings. A steady series of earthquakes had already struck Trinidad in the past, including a magnitude 4.6 quake in 2001 that the U.S. Geological Survey (USGS) has investigated for links to wastewater injection.
The new study found also that Japan’s devastating magnitude 9.0 earthquake on March 11, 2011 triggered a swarm of earthquakes in the west Texas town of Snyder, where injection of fluid to extract oil from the nearby Cogdell fields has been setting off earthquakes for years, according to a 1989 study in the Bulletin of the Seismological Society of America. About six months after the Japan quake, a magnitude 4.5 quake struck Snyder.
Those smaller earthquakes–triggered by bigger quakes elsewhere–can make faults more stressed and eventually lead to larger quakes.
For decades, the thought that earthquakes in one part of the world can cause quakes elsewhere was controversial. But for the past 20 years, scientists have known that big earthquakes can cause tremors in places like hydrothermal fields, which naturally have the high fluid pressure found in fracking sites. It makes sense that man-made high pressure areas would follow suit.
Now that the Columbia researchers have made the link between fracking and far-off quakes, future studies will have to confirm it–and figure out the details of where exactly waste injections stress fault lines.