From Bureau of Economic Geology, The University of Texas at Austin (
For more information, please contact the author.

Bureau Seminar, September 21, 2007

What every geologist (or lesser mortal) should
know about fracture mechanics

Jon Olson

Petroleum and Geosystems Engineering Dept. , The University of Texas at Austin


This is a review talk designed to introduce a geologic audience to the concepts of fracture mechanics and how they can be applied to make conceptual and quantitative interpretations of natural fracture phenomena.  Examples are driven by outcrop and core observations and explained conceptually with simple analytical equations from fracture mechanics.  The talk focuses on opening mode fractures (joints, veins, dikes) and how fracture mechanics can be used to predict their geometric attributes.  Examples include the relationship between in situ stress anisotropy and propagation paths, theoretical predictions of fracture length, fracture spacing and aperture versus length distributions, the role of subcritical (stress corrosion) cracking on fracture clustering, and the concept of natural hydraulic fracturing.  The influence of simultaneous diagenesis and fracture growth will also be discussed in the context of preserved fracture aperture (e.g., how does a fracture stay open when the driving stress is gone?).