Superplastic nanofibrous slip zones control seismogenic fault friction

Understanding the internal mechanisms controlling fault friction is crucial for understanding seismogenic slip on active faults. Displacement in such fault zones is frequently localized on highly reflective (mirrorlike) slip surfaces, coated with thin films of nanogranular fault rock. We show that m...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2014-12, Vol.346 (6215), p.1342-1344
Main Authors: Verberne, Berend A., Plümper, Oliver, de Winter, D.A. Matthijs, Spiers, Christopher J.
Format: Article
Language:English
Subjects:
Calcite
Classical mechanics
Earthquakes
Fault lines
Fault zones
Faults
Fibers
Friction
Geological faults
Grain boundaries
Mass transfer
Materials
Materials science
Microstructure
Nanostructure
Plate tectonics
Rupture
Seismic phenomena
Seismology
Sintering
Sliding
Slip
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Summary:Understanding the internal mechanisms controlling fault friction is crucial for understanding seismogenic slip on active faults. Displacement in such fault zones is frequently localized on highly reflective (mirrorlike) slip surfaces, coated with thin films of nanogranular fault rock. We show that mirror-slip surfaces developed in experimentally simulated calcite faults consist of aligned nanogranular chains or fibers that are ductile at room conditions. These microstructures and associated frictional data suggest a fault-slip mechanism resembling classical Ashby-Verrall superplasticity, capable of producing unstable fault slip. Diffusive mass transfer in nanocrystalline calcite gouge is shown to be fast enough for this mechanism to control seismogenesis in limestone terrains. With nanogranular fault surfaces becoming increasingly recognized in crustal faults, the proposed mechanism may be generally relevant to crustal seismogenesis.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1259003