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Slip complexity in dynamic models of earthquake faults
J S Langer1, J M Carlson, C R Myers
1Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA.
Summary
Earthquake fault models with unstable friction laws can generate complex slip behaviors. These models, including 1D and 2D simulations, show chaotic sequences of large events, mimicking real fault properties.
Area of Science:
- Geophysics
- Computational Seismology
- Fault Mechanics
Background:
- Earthquake fault behavior is often modeled using friction laws.
- Externally imposed heterogeneities are traditionally included to explain slip complexity.
- Recent evidence suggests intrinsic fault properties may drive complexity.
Purpose of the Study:
- To investigate earthquake fault slip complexity using models with dynamically unstable friction.
- To demonstrate that complex slip behavior can arise without external heterogeneities.
- To compare a 1D and a 2D model for fault slip dynamics.
Main Methods:
- Development of a one-dimensional model with velocity-weakening stick-slip friction.
- Development of a two-dimensional elastodynamic model with slip-weakening friction.
- Analysis of slip patterns, event sequences, and event composition.
Main Results:
- Both models exhibit complexity in small slip events.
- Chaotic sequences of large characteristic events were observed in both models.
- Large events in both models were characterized by Heaton pulses.
Conclusions:
- Dynamically unstable friction laws are sufficient to produce complex earthquake fault slip.
- The models provide a plausible representation of real fault properties.
- Intrinsic fault physics, rather than external factors, can explain slip complexity.