Comments on: Yo, Podrock. https://habitablezone.com/2016/09/04/yo-podrock-4/ Tue, 07 Apr 2026 19:18:10 -0700 hourly 1 http://wordpress.org/?v=3.3.1 By: podrock https://habitablezone.com/2016/09/04/yo-podrock-4/#comment-37434 podrock Mon, 05 Sep 2016 16:53:47 +0000 https://www.habitablezone.com/?p=59664#comment-37434 Note that it is the disposal of fracking fluids in deep wells that is suspected, not the fracking itself. Anytime you change the pore pressure of rock, you change how it responds to differential stress. Adding fluids decreases the amount of stress needed to rupture the rock. This has been very well documented in both the lab and the field. When the deep pumping of fluid caused earthquakes in Denver back in the 1960's, it was believed that the fluids allowed existing tectonic stresses to fracture the rock. However, I don't expect there to be a whole lot of tectonic stress in this part of the craton. I have a suspicion, and that's all it is, that the injections are causing localized pressure gradients that produce the differential stress in the weakened rock. I have not seen this possibility discussed in the literature but I really haven't looked into this for some time. Note that it is the disposal of fracking fluids in deep wells that is suspected, not the fracking itself.

Anytime you change the pore pressure of rock, you change how it responds to differential stress. Adding fluids decreases the amount of stress needed to rupture the rock. This has been very well documented in both the lab and the field.

When the deep pumping of fluid caused earthquakes in Denver back in the 1960′s, it was believed that the fluids allowed existing tectonic stresses to fracture the rock. However, I don’t expect there to be a whole lot of tectonic stress in this part of the craton.

I have a suspicion, and that’s all it is, that the injections are causing localized pressure gradients that produce the differential stress in the weakened rock. I have not seen this possibility discussed in the literature but I really haven’t looked into this for some time.

]]>