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Shear localisation controls the dynamics of earthquakes
Fabian Barras1, Nicolas Brantut2,3
1The Njord Centre, Department of Physics, Department of Geosciences, University of Oslo, Oslo, Norway. fabian.barras@mn.uio.no.
Nature Communications
|January 17, 2025
Summary
Earthquakes result from fault slip, driven by energy balance. This study reveals extreme strain localization in faults, significantly reducing fracture energy and establishing a new scaling law for rupture speed.
Area of Science:
- Geophysics
- Solid Earth Physics
- Computational Seismology
Background:
- Earthquakes originate from rapid slip along tectonic faults.
- Fault slip dynamics depend on elastic energy and energy dissipation at the rupture tip.
- Energy dissipation is controlled by thermo-hydro-mechanical processes at small scales.
Purpose of the Study:
- To numerically simulate shear ruptures using a dual-scale approach.
- To couple sub-millimeter fault processes with kilometer-scale elastodynamics.
- To investigate the impact of strain localization on earthquake rupture dynamics and energy.
Main Methods:
- Dual-scale numerical simulation of shear ruptures.
- Coupling of sub-millimeter fault physics with large-scale elastodynamics.
- Analysis of strain localization and fracture energy.
Main Results:
- Sudden shear strain localization leads to classical crack behavior with constant fracture energy.
- Localized strain fracture energy is significantly lower than predicted by models with uniform shearing.
- A unique scaling law exists between localized shearing width and rupture speed.
Conclusions:
- Earthquakes are characterized by extreme strain localization within faults.
- This localization fundamentally alters energy dissipation mechanisms.
- The findings provide new insights into earthquake physics and scaling laws.
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