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Dynamic restrengthening and fault heterogeneity explain megathrust earthquake complexity.
Jeremy Wing Ching Wong1, Alice-Agnes Gabriel2,3, Wenyuan Fan2
1Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography University of California, San Diego, CA, USA. jeremywong@ucsd.edu.
Nature Communications
|April 27, 2026
Summary
Megathrust earthquakes exhibit complex rupture dynamics. This study shows that fault heterogeneity and rapid frictional restrengthening can self-consistently generate this complexity, crucial for seismic and tsunami hazard assessments.
Area of Science:
- Geophysics
- Seismology
- Earthquake Science
Background:
- Megathrust faults generate Earth's largest earthquakes, posing significant seismic and tsunami risks.
- The 2011 Tohoku-Oki earthquake showcased complex rupture dynamics, including multiple episodes and significant tsunamigenic slip, prompting research into underlying causes.
Purpose of the Study:
- To investigate how preexisting physical conditions on megathrust faults can lead to complex earthquake rupture dynamics.
- To model the spontaneous emergence of rupture complexity observed in events like the Tohoku-Oki earthquake.
Main Methods:
- Utilized an ensemble of 3D dynamic rupture simulations.
- Incorporated data-informed fault heterogeneity and rapid coseismic frictional restrengthening.
Main Results:
- Demonstrated that fault heterogeneity and dynamic frictional processes can spontaneously generate complex rupture patterns.
- Successfully reproduced depth-dependent rupture speeds, multiple rupture fronts, and large trench-side slip consistent with the Tohoku-Oki earthquake.
- Identified dynamic stress redistribution and episodic reactivation as key drivers of mixed pulse-like and crack-like rupture propagation.
Conclusions:
- Preexisting fault heterogeneity and dynamic frictional effects (weakening and restrengthening) are critical drivers of megathrust rupture complexity.
- Physics-based models incorporating dynamic effects are essential for accurate seismic and tsunami hazard assessments.
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