Science magazine yesterday published an important paper that documents that the rate of earthquakes greater than 3.0 jumped sharply since 2001. From 1967 to 2001, earthquakes of 3.0 or greater averaged 21 per year. But since 2001, such earthquakes rose sharply to 188 per year.
http://www.sciencemag.org/content/341/6142/1225942.abstract.
Why the sharp increase?
The authors state: "It has long been known that impoundment
of reservoirs, surface and underground
mining, withdrawal of fluids and gas from the subsurface, and injection
of fluids into
underground formations are capable of
inducing earthquakes."
There is definitive evidence that deep well injection of fluids, including gas drilling wastewater, can cause an earthquake. It did cause a 4.0 earthquake that was felt at the surface in Youngstown, Ohio.
Interesting article.
ReplyDeleteI do think that context is important there though as the earthquake situation is a big buzz word and hype point for opponents of fracking and natural gas. As mentioned in your post, anything that involves the removal of rocks/fluids and the injection of fluids will influence seismic activity. We are all aware that coal mining, oil drilling, and geothermal all increase earthquake likelyhood. In my opinion, the real question is how does the seismic activity compare to relative energy withdrawn?
For example, if natural gas induces slightly larger earthquakes than geothermal, but results in 10x energy yield, that is certainly still a good thing, as the earthquakes are not strong enough to do any real damage.