EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Fault (un-)stability and strain partitioning across the brittle-ductile transition

Jérôme Aubry1, François Passelègue2, Javier Escartín1, Damien Deldicque1, Julien Gasc1, Samson Marty1, Marine Page3, and Alexandre Schubnel1
Jérôme Aubry et al.
  • 1École Normale Supérieure, Laboratoire de Géologie, Paris, France
  • 2École Polytechnique Fédérale, Lausanne, Switzerland
  • 3Sole trader

In the lithosphere, the transition from brittle to ductile deformation corresponds to a regime where brittle fracturing and plastic flow coexist, called the semi-brittle deformation zone. Within these different regimes, a large fault slip spectrum has been observed, from fast to slow earthquakes. Studying the parameters controlling fault (un-)stability and strain partitioning across this transition is fundamental to understand how natural faults behave at varying crustal depths.

To investigate semi-brittle deformation and the conditions promoting it, we report here the results of experiments performed on Carrara marble saw-cut faults in triaxial conditions. We studied the influence of the confining pressure, axial loading rates and initial fault roughness on fault (un-)stability. From mechanical data, we performed strain partitioning calculations to infer elastic, frictional and plastic strain contributions during the deformation process.

We conclude that (laboratory) earthquakes may nucleate within a regime where homogeneous plastic deformation of the bulk and dynamic fault slip may coexist. The contribution of plastic strain is promoted with increasing confining pressure and fault roughness.

How to cite: Aubry, J., Passelègue, F., Escartín, J., Deldicque, D., Gasc, J., Marty, S., Page, M., and Schubnel, A.: Fault (un-)stability and strain partitioning across the brittle-ductile transition, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4092,, 2020

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