TY - JOUR
T1 - Effects of temperature on the frictional behavior of material from the Alpine Fault Zone, New Zealand
AU - Valdez, R. D.
AU - Kitajima, H.
AU - Saffer, D. M.
N1 - Funding Information:
The authors wish to thank Jean-Philippe Avouac, André Niemeijer, and Elena Spagnuolo, Philippe Agard for reviews that greatly contributed to the quality of the manuscript. This work was funded by National Science Foundation award EAR-1215856 to DS and a Geological Society of America student grant to RV. DFDP-1 was funded by GNS Science , Victoria University of Wellington , the University of Otago , the University of Auckland , the University of Canterbury , Deutsche Forschungsgemeinschaft and the University of Bremen , the Natural Environment Research Council and the University of Liverpool , and the Marsden Fund of the Royal Society of New Zealand . We thank Miki Takahashi for her assistance with our experiments at the Geological Survey of Japan and the DFDP-1 Alpine Fault team led by Rupert Sutherland, John Townend and Virginia Toy.
Funding Information:
The authors wish to thank Jean-Philippe Avouac, André Niemeijer, and Elena Spagnuolo, Philippe Agard for reviews that greatly contributed to the quality of the manuscript. This work was funded by National Science Foundation award EAR-1215856 to DS and a Geological Society of America student grant to RV. DFDP-1 was funded by GNS Science, Victoria University of Wellington, the University of Otago, the University of Auckland, the University of Canterbury, Deutsche Forschungsgemeinschaft and the University of Bremen, the Natural Environment Research Council and the University of Liverpool, and the Marsden Fund of the Royal Society of New Zealand. We thank Miki Takahashi for her assistance with our experiments at the Geological Survey of Japan and the DFDP-1 Alpine Fault team led by Rupert Sutherland, John Townend and Virginia Toy.
PY - 2019/7/5
Y1 - 2019/7/5
N2 - Temperature is widely believed to act as a primary control on fault rheology, and therefore on the distribution of seismicity along plate boundary faults. However, there are few detailed measurements of the frictional strength and stability of natural fault gouges at elevated temperatures. Here, we report on a suite of shearing experiments designed to investigate the frictional behavior of fault rocks sampled from depths of 111.5–142.9 m along the Alpine Fault in New Zealand obtained by the International Continental Scientific Drilling Program (ICDP) Deep Fault Drilling Project (DFDP). We tested five samples from the DFDP-1B pilot hole: two hanging wall chloritic cataclasites, two footwall granitic cataclasites, and a fault gouge from the principal slip zone (PSZ-1). Each sample was sheared at a range of temperatures from 23 to 500 °C and at an effective normal stress of 80 MPa. The wall rock cataclasites exhibit an increase in the friction coefficient (μ) with temperature, from μ = 0.45–0.64 at 23 °C to μ = 0.87 at 500 °C. The PSZ-1 gouge exhibits lower friction coefficient values than the wall rock at temperatures ≤180 °C (μ = 0.35–0.46 vs 0.45–0.65), but comparable values (μ = 0.87–0.90) at 500 °C. The variation in frictional strength is accompanied by a transition from velocity-strengthening to velocity-weakening behavior at temperatures ≥180 °C for all materials. Extrapolation of the experimentally defined rheological critical stiffness of the fault material and the estimated in situ stiffness of the surrounding crust suggests upper and lower stability boundaries at ~1.8–2.5 km and ~8.5–8.8 km depth, respectively. The upper stability boundary is also consistent with the observed depth-frequency distribution of earthquakes.
AB - Temperature is widely believed to act as a primary control on fault rheology, and therefore on the distribution of seismicity along plate boundary faults. However, there are few detailed measurements of the frictional strength and stability of natural fault gouges at elevated temperatures. Here, we report on a suite of shearing experiments designed to investigate the frictional behavior of fault rocks sampled from depths of 111.5–142.9 m along the Alpine Fault in New Zealand obtained by the International Continental Scientific Drilling Program (ICDP) Deep Fault Drilling Project (DFDP). We tested five samples from the DFDP-1B pilot hole: two hanging wall chloritic cataclasites, two footwall granitic cataclasites, and a fault gouge from the principal slip zone (PSZ-1). Each sample was sheared at a range of temperatures from 23 to 500 °C and at an effective normal stress of 80 MPa. The wall rock cataclasites exhibit an increase in the friction coefficient (μ) with temperature, from μ = 0.45–0.64 at 23 °C to μ = 0.87 at 500 °C. The PSZ-1 gouge exhibits lower friction coefficient values than the wall rock at temperatures ≤180 °C (μ = 0.35–0.46 vs 0.45–0.65), but comparable values (μ = 0.87–0.90) at 500 °C. The variation in frictional strength is accompanied by a transition from velocity-strengthening to velocity-weakening behavior at temperatures ≥180 °C for all materials. Extrapolation of the experimentally defined rheological critical stiffness of the fault material and the estimated in situ stiffness of the surrounding crust suggests upper and lower stability boundaries at ~1.8–2.5 km and ~8.5–8.8 km depth, respectively. The upper stability boundary is also consistent with the observed depth-frequency distribution of earthquakes.
UR - http://www.scopus.com/inward/record.url?scp=85064917047&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85064917047&partnerID=8YFLogxK
U2 - 10.1016/j.tecto.2019.04.022
DO - 10.1016/j.tecto.2019.04.022
M3 - Article
AN - SCOPUS:85064917047
VL - 762
SP - 17
EP - 27
JO - Tectonophysics
JF - Tectonophysics
SN - 0040-1951
ER -