Dynamic Emergence of Plate Motions and Great Megathrust Earthquakes Across Length and Time Scales

Abstract

The slow motion of tectonic plates over thousands of kilometers is intermittently interrupted by great earthquakes with sudden slips localized near convergent plate boundaries. We developed a subduction model that self-consistently integrates buoyancy forces, diffusion and dislocation creep, and inter-plate friction. From the nonlinear dynamics emerge long-term plate motions that achieve velocities of ≈5 cm/year, effective viscosities of ≈1⁢0¹⁹ Pa⋅s below plates, and sudden slips up to ≈10 m repeating every several hundred years. Along-strike resistance arising from long-wavelength variation of coseismic slip is naturally incorporated with a rupture length scale, L. Computations with L∼1⁢0³ km generate events with M_w≈9. When L decreases, there is a commensurate decrease in the effective moment of rupture events. Predicted long-term plate velocities, mantle viscosities, cycles of stress loading and release, and rupture event size and magnitude all show good agreement with observations.

Copyright and License

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

This work is partially supported by the National Science Foundation (NSF) through EAR-2343864. We acknowledge use of the Anvil supercomputer at Purdue University and the Stampede3 supercomputer at the Texas Advanced Computing Center (TACC), supported by the NSF ACCESS program EAR160027. We would like to thank Yida Li, Wei Mao and Luca Dal Zilio for helpful discussions and Roger Buck for his constructive review.

Funding

This work is partially supported by the National Science Foundation (NSF) through EAR-2343864. We acknowledge use of the Anvil supercomputer at Purdue University and the Stampede3 supercomputer at the Texas Advanced Computing Center (TACC), supported by the NSF ACCESS program EAR160027.

Contributions

Conceptualization: Jiaqi Fang, Michael Gurnis, Nadia Lapusta.
Data curation: Jiaqi Fang.
Formal analysis: Jiaqi Fang.
Funding acquisition: Michael Gurnis, Nadia Lapusta.
Methodology: Jiaqi Fang, Michael Gurnis, Nadia Lapusta.
Project administration: Michael Gurnis, Nadia Lapusta.
Resources: Jiaqi Fang, Michael Gurnis.
Software: Jiaqi Fang.
Supervision: Michael Gurnis, Nadia Lapusta.
Validation: Jiaqi Fang, Michael Gurnis, Nadia Lapusta.
Visualization: Jiaqi Fang.
Writing – original draft: Jiaqi Fang.

Data Availability

The code used in this study can be accessed through GitHub (Fang, 2024b). The computations are completed using the open-source package Underworld2 version v2.10.0b (Mansour et al., 2020). The model data for producing all the figures are available on CaltechDATA (Fang, 2024a).

Supplemental Material

Supporting information (PDF).

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Geophysical Research Letters - 2024 - Fang - Dynamic Emergence of Plate Motions and Great Megathrust Earthquakes Across.pdf

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