We’ve written about fracking and earthquakes before.  Now some Canadian scientists have gone and done a study of fracking and earthquakes, and determined that fracking causes earthquakes in certain places in the Great White North.

There are a couple of important points made in the article.

The first is that earthquakes have not been caused by fracking in the United States.  At least, not often.  I suspect that fracking has caused more earthquakes than the industry would like to admit.  However, the studies don’t appear to support a strong relationship between fracking and earthquakes.  Luckily, the earthquakes that do appear to be caused by fracking are small enough that they don’t typically do damage, and the huge majority of them aren’t even felt by anybody.  The recent earthquake in Cushing, Oklahoma was enough to do some damage, however, and may (or may not) have occurred because of fracking.  The trouble is, it’s almost impossible to determine whether fracking caused it.

The other point in the article is that the earthquakes were caused in two ways, “by increases in pressure as the fracking occurred, and, for a time after the process was completed, by pressure changes brought on by the lingering presence of fracking fluid.”

In other words, it was the change in pressure that triggered the earthquakes, not lubrication of a fault.  I had previously understood that lubrication could cause an earthquake, but this study throws serious doubt on that.

The article points out that different areas react differently.  Some places will have no fracking-induced earthquakes, others will, and some areas will have wastewater injection-induced earthquakes.  As usual, there is not one-size-fits-all answer here.  It seems that different geology leads to different results.

If you’d like to do some more reading about fracking-induced and injection-induced earthquakes, the USGS has a couple of  web pages on the subject.

There was a 5.0 earthquake near Cushing, Oklahoma.  There was some damage to downtown buildings.  No people were hurt, thankfully.

Of course, anyone who is involved in oil and gas or who is an environmentalist knows that the speculation will center around disposal wells being the cause.

Disposal wells are used to get rid of produced water, or the water that comes back out of a well after fracking and other stimulation processes.  Disposal wells have been used for almost as long as oil and gas production has been a thing.  Disposal has become a concern in recent years because horizontal fracking creates a lot more produced water than conventional processes ever did.  The theory is that injecting that much water into underground formations is lubricating fault lines, thus making it easier for earthquakes to occur, and also creating pressure imbalances that need to be released, thus making it more likely that an earthquake will occur.

So far, there is only a possible correlation, not an actual cause/effect relationship, between disposal wells and earthquakes.  The correlation is there, but it could just as easily be a coincidence.  Some things are going to be hard to prove, of course.  How do you prove exactly what’s going on thousands of feet underground?

Here in West Virginia, there’s a big water treatment plant being built.  It will handle a lot of produced water, so the produced water won’t have to be injected into the ground.  If disposal of produced water in injection wells is causing earthquakes, it will be less likely to happen here.

Interesting random fact: Cushing, OK is home to one of the largest oil hubs in the world.