2017/02/11 by Carolyn Boulton, Lu Yao, D. R. Faulkner +7 · 1 citation
Earth and Planetary Sciences · Engineering · #High-pressure geophysics and materials #Rock Mechanics and Modeling #earthquake and tectonic studies
paper · doi:10.1016/j.jsg.2017.02.003
openalex publication_date 2017/02/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The Alpine Fault in New Zealand is a major plate-bounding structure that typically slips in ∼M8 earthquakes every c. 330 years. To investigate the near-surface, high-velocity frictional behavior of surface- and borehole-derived Alpine Fault gouges and cataclasites, twenty-one rotary shear experiments were conducted at 1 MPa normal stress and 1 m/s equivalent slip velocity under both room-dry and water-saturated (wet) conditions. In the room-dry experiments, the peak friction coefficient ( μ p = τ p / σ n ) of Alpine Fault cataclasites and fault gouges was consistently high (mean μ p = 0.67 ± 0.07). In the wet experiments, the fault gouge peak friction coefficients were lower (mean μ p = 0.20 ± 0.12) than the cataclasite peak friction coefficients (mean μ p = 0.64 ± 0.04). All fault rocks exhibited very low steady-state friction coefficients ( μ ss ) (room-dry experiments mean μ ss = 0.16 ± 0.05; wet experiments mean μ ss = 0.09 ± 0.04). Of all the experiments performed, six experiments conducted on wet smectite-bearing principal slip zone (PSZ) fault gouges yielded the lowest peak friction coefficients ( μ p = 0.10–0.20), the lowest steady-state friction coefficients ( μ ss = 0.03–0.09), and, commonly, the lowest specific fracture energy values ( E G = 0.01–0.69 MJ/m 2 ). Microstructures produced during room-dry and wet experiments on a smectite-bearing PSZ fault gouge were compared with microstructures in the same material recovered from the Deep Fault Drilling Project (DFDP-1) drill cores. The near-absence of localized shear bands with a strong crystallographic preferred orientation in the natural samples most resembles microstructures formed during wet experiments. Mechanical data and microstructural observations suggest that Alpine Fault ruptures propagate preferentially through water-saturated smectite-bearing fault gouges that exhibit low peak and steady-state friction coefficients.