Linear Elastic Fracture Mechanics:

Analytical Fracture Mechanics Solutions

Numerical Analysis: Boundary Element Modeling

The basis for much of our understanding of the earth stems from the work of scientists over the last several millennia who developed the tools of geometry, trigonometry, algebra, calculus, and materials science.

These theories help explain the phenomena of fracture formation, propagation and earthquake behaviors.

In this section I have used Poly3D to fit the shape of the slip distribution and the direction of slip under simple, geologically reasonable boundary conditions.

Although not unique, this model suggests that only a relatively limited set of geologically viable stress conditions can reproduce the observed slip data. The sensitivity to our stress model for Segment 3 is plotted at bottom left: here the model conditions including the relative magnitudes and orientations of the principal stress components were systematically varied.

Collaboration with Peter Eichhubl

Collaboration with Peter Eichhubl

The essential concepts in fracture mechanics are that flaws concentrate stress, strain and displacements in the material surrounding them.

These flaws could be fractures themselves, or any structure that alters the stiffness of a material in a geometrically confined region such as pores, fossils, or variations in rock type.

Continuum mechanics, which idealizes materials as simple, continuous bodies bounded by surfaces can be used to model how these flaws influence stress, strain, and displacement.

Slickenlines on the fault surface record the direction of slip (photo courtesy of John Solum)

Poly3D

Poly3D

Deformation of layered sandstone and shale. Notice that although these two rock types are immediately adjacent to each other they deform differently. The sandstone breaks into distinct bodes separated by fractures. The shale “flows” without macroscopic fracture and remains continuous across the fault.