Field measurements of the roughness of fault surfaces

Abstract

We recorded the height of a granitic fault surface as a function of position along one‐dimensional profiles. We show that the profiles exhibit an “anisotropic” scaling invariance: self‐affinity. The difference between the maximum and the minimum height, and the standard deviation of the height, over a length L are proportional to Lζ, where ζ ≈ 0.84. Other properties such as the Return Probability distribution or the Power Spectrum of the profile comfort this result. This self‐affine property is in good agreement with recent works on artificial fractured surfaces. Previous studies at field scale are consistent with this concept.