The influence of length scale on rock strength

Observations indicate that rocks become weaker as they increase in length scale. This trend implies that measurements of mechanical properties made at the laboratory scale (mm or cm) may not apply to km-scale volumes of crustal rock, and thus has important implications for plate tectonics. This result is generally attributed to the presence of defects and weaknesses in larger and larger rock masses.

However, the community presently lacks a complete understanding of the function that relates the length or number of weaknesses to the degree that larger volumes of crust weaken, e.g., a decrease in uniaxial compressive strength.

To constrain the relationship between the degree of weakening and characteristics of defects, this project will use discrete element method numerical models. The project will compare the influence of length scale on macroscopic strength in numerical rock volumes with populations of weaknesses.

Please contact Jess McBeck ( for more information.

Image may contain: Facial expression, Rectangle, Product, Font, Red.
Fig. 1 Fault development in a discrete element method model. Click here for a bigger version.


Published Aug. 16, 2022 9:37 AM - Last modified Aug. 16, 2022 9:37 AM


Scope (credits)