Mag 5.8 (upgraded from 5.6) Earthquake, Pawnee, Oklahoma

[Ophiolite]

Thank you for the Bloomberg article. I shall read it more carefully tomorrow.

In any case, it is not fracking that is causing the quakes.

You have made this assertion three times now, but have not provided evidence to support it. (The Bloomberg article is inconclusive on the point and, more to the point, is newspaper article, not a research paper.) In contrast I have cited a paper that notes the potential of fracking to induce earthquakes. Do you intend to provide any support for your assertion, or may I accept it simply as your opinion?

The exact cause of a particular quake happening at a particular moment is almost unknowable. Tensions and stresses build up in faults over geologic time. One theory is that the injection water may make it easier to slip and relieve the stress today instead of 10 years from now.

However, as I noted in an earlier post, conventional earthquakes are not the only means of relieving stresses. So called slow earthquakes, whose effects are - from an economic and safety standpoint - non-existent may be doing this. Then, in Oklahoma, fracking or water injection may be overcoming that mechanism by sufficiently altering the stress fields, or fracture networks and thereby inducing conventional earthquakes that would not otherwise occur.

However, [injection water] does not induce the stress. That results from plate tectonics.

Just to be pedantic, but more thorough. The stress may arise from isostatic adjustment to post-ice age ice removal, while earthquakes may also be a consequence of volcanic activity and landslides.

 

[1oldman2]

New news on the subject.
https://phys.org/news/2017-12-geologists-discoveries-kansas-oklahoma-earthquakes.html