Marthe G. Guren1,*, Henrik A.
Sveinsson1, Anders Malthe-Sørenssen1and François Renard1,2
1The Njord Centre, Departments of Geosciences and
Physics, University of Oslo, Norway
2ISTerre, Univ. Grenoble Alpes, Grenbole INP, Univ.
Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, 38000 Grenoble,
France
*Corresponding author: Marthe Guren (m.g.guren@geo.uio.no)
Key Points:
- Dynamic tensile rupture propagation simulated in alpha-quartz using
molecular dynamics simulations
- A path instability occurs when the rupture speed is greater than 15 %
of the Rayleigh wave speed
- Microbranching may lead to a production of fragments with sizes below
the grinding limit
Abstract
The creation of new fractures controls fault slip, produces rock damage,
and contributes to the dissipation of energy during earthquakes.
Pulverized rocks around faults contain grains with a wide range of
sizes, but the mechanisms that produces nanoscale grains remain elusive.
Using molecular dynamics simulations, we model tensile rupture
propagation in alpha-quartz under conditions of stress that occur during
earthquake propagation. Our results show that for rupture speeds below
15 % of the Rayleigh wave speed, the fracture propagates straight. At
higher speeds, fracture propagation undergoes path instabilities with
crack oscillations and microbranching. We show that microbranching can
lead to nanoscale fragments. Energy dissipation occurs by the creation
of fracture surfaces and material damage; the dissipated energy
increases with rupture speed. This nanoscale mechanism of irreversible
deformation during earthquake propagation conditions contributes to the
energy budget of earthquakes, and damage production in fault zones.