A new study led by a researcher at Cornell University confirms what we’ve known for some time now: that the massive wastewater injection associated with “fracking” (hydraulic fracturing) has greatly increased earthquake activity. In this case, the area of study is Oklahoma.
An inset to figure 1 of that paper shows the dramatic increase, comparing Oklahoma earthquake counts per thousand square kilometers (in red) to what has been observed in California (in blue):
Note that the highest count for Oklahoma — by a substantial margin — is for 2014, despite the fact that when the data were retrieved for this paper we were only three months into the year. The count by now (with 2014 half over) is higher.
I retrieved earthquake data for the region from longitude 103.1 W to 94 W, latitude 33.5 N to 37 N, which includes all of Oklahoma and part of Texas. I only included earthquakes of magnitude 3 or higher. Here are the annual counts, when including 2014 data through the first few days of July:
It looks reminiscent of … what’s that shape? … a hockey stick. By year’s end, the 2014 count will be even higher.
That’s powerful evidence of a causal relationship. But there’s more. The paper gives the location of the main wastewater injection wells in Oklahoma, so from the location of each earthquake we can compute the distance to the nearest injection well. Do the post-2009 earthquakes tend to be closer to the injection well locations than the pre-2009 earthquakes?
Yes, they do:
By this time, it’s abundantly obvious that yes, wastewater injection associated with fracking is the cause of the dramatic increase in earthquake activity in Oklahoma. And the increase has indeed been dramatic; the aforementioned paper states:
Seismic swarms within Oklahoma dominate the recent seismicity in the central and eastern United States (9), contributing 45% of M3 and larger earthquakes between 2008-2013 (10). No other state contributed more than 11 % … These earthquakes are part of a 40-fold increase in seismicity within Oklahoma during 2008-2013 as compared to 1976-2007.
Considering how obvious the causal relationship has been, for some time now, I have to wonder why the fossil fuel industry has spent so much time and effort trying to deny it. Considering how undeniable the relationship is now, I have to wonder whether or not the fossil fuel industry will continue to deny it.