Nanoscale Roughness of Natural Fault Surfaces Controlled by Scale-Dependent Yield Strength

作者：Thom C A^*; Brodsky E E; Carpick R W; Pharr G M; Oliver W C; Gold**y D L

来源：Geophysical Research Letters, 2017, 44(18): 9299-9307.

DOI：10.1002/2017GL074663

• fault roughness
• nanoindentation
• atomic force microscopy
• yield strength

Many natural fault surfaces exhibit remarkably similar scale-dependent roughness, which may reflect the scale-dependent yield strength of rocks. Using atomic force microscopy (AFM), we show that a sample of the Corona Heights Fault exhibits isotropic surface roughness well-described by a power law, with a Hurst exponent of 0.75 +/- 0.05 at all wavelengths from 60 nm to 10 m. The roughness data and a recently proposed theoretical framework predict that yield strength varies with length scale as lambda(-0.25+/-0.05). Nanoindentation tests on the Corona Heights sample and another fault sample whose topography was previously measured with AFM (the Yair Fault) reveal a scale-dependent yield stress with power-law exponents of -0.12 +/- 0.06 and -0.18 +/- 0.08, respectively. These values are within one to two standard deviations of the predicted value, and provide experimental evidence that fault roughness is controlled by intrinsic material properties, which produces a characteristic surface geometry.

• 出版日期2017-9-28