I recently became aware of some research that suggests that we are increasing the incidence of earthquakes by injecting waste water back underground. The research was published by William L. Ellsworth in Science in July 2013 in a paper entitled “Injection-Induced Earthquakes”. This work is also well described on the US Geological Survey (USGS) website in an article entitled “Man-Made Earthquakes Update“ published in January 2014.
The graph that really caught my eye was this one;
Notice how from 2009 there has been a dramatic rise in the incidence of US earthquakes? This really startled me. It appears that we are making earthquakes. The USGS article notes that;
USGS scientists have found that at some locations the increase in seismicity coincides with the injection of wastewater in deep disposal wells.
What is “waste” water?
Basically what they are calling “waste water” here is a by-product of oil and gas production. When energy companies get oil and gas out of the ground, they also get a lot of water which is often very salty and not suitable to mix into the water table. Sometimes water and chemicals are injected below the oil and gas to help force it out of the ground and this chemical laden water is produced as well. The important thing is to ensure that this “waste water” is not mixed in with our water supply. The USGS article notes that;
Often, it is most economical to geologically sequester such wastewater by injecting it underground, deep below any aquifers that provide drinking water.
This is where alarm bells start ringing for me. When something is “most economical” if often means “bad for the environment” at the same time.
How does this result in making earthquakes?
This is fairly simple. Pumping lots of water into deep rock formations just makes things more slippery. If there’s a suitable fault or fracture in the rock layers, this extra slipperiness provided by the water might be just enough to allow it to snap loose and slide a bit, causing an earthquake. The USGS article makes the following quote;
Wastewater injection increases the underground pore pressure, which may, in effect, lubricate nearby faults thereby weakening them. If the pore pressure increases enough, the weakened fault will slip, releasing stored tectonic stress in the form of an earthquake. Even faults that have not moved in millions of years can be made to slip and cause an earthquake if conditions underground are appropriate.
Be careful when exploiting the Earth
It’s not all doom and gloom. The USGS says that only a small percentage of the wells designed to sequester waste water appear to cause earthquakes. However, the graph above is very worrying. Also, the case they site in Oklahoma (see picture) shows how these earthquakes can have a very real effect on peoples lives.
The USGS also clearly states that “fracking” is not a culprit here. The process of “fracking” creates many “micro” quakes that are really so weak they can’t be felt (the danger is in the chemicals used to do the fracking, but that’s another story). Anyway, it’s clear that “fracking” is not making earthquakes like the ones being discussed here.
The bottom line for me is that we should take extreme care when “exploiting” our Earth. It’s the only one we’ve got. If the big companies look only for the “most economical” solution to their problems, and don’t take into account the real impact they are having on our Earth, then governments (us) will have to enforce the right level of control.
There is the wonderful quote from Buddha;
Without doing any harmful act,
Abundantly perform beneficial acts,
Completely tame your mind,
That is my teaching.
which starts by saying that we should do nothing harmful (the same sentiment is suggested by Patanjali). This should really be the foundation of any attempt to “exploit” our Earth.