Large-Scale Slab Dynamics as Drivers of Seismicity: Modeling Earthquakes in the Izu-Bonin-Mariana Subduction Zones

Subduction zones host the majority of global earthquakes, from shallow megathrust and outer-rise to deep intraplate earthquakes. Although it is well established that subducting slabs are the primary energy source for most earthquakes, the quantitative relationship between slab dynamics and seismic events remains poorly understood. In this study, we develop a comprehensive 3D geodynamic model of the Izu-Bonin-Mariana subduction system to connect long-term slab dynamics with earthquake activity. Our comparison of the modeled stress state predictions with observed earthquake focal mechanisms reveals that both shallow megathrust and outer-rise earthquakes, as well as deep earthquakes associated with plate bending at the mantle transition zone, can be explained by slab dynamics. However, the intermediate-depth (150-300km) earthquakes remain enigmatic. Additionally, our findings show a notable spatial correlation between the slab’s energy dissipation rate and the distribution of seismic activity. These correlations between model predictions and observed earthquake characteristics underscore the profound connection between earthquakes and the large-scale, long-term dynamics of mantle flow and subduction.