Subduction plate boundary thrust system and dynamic characteristics in the Western Pacific

The majority of the world's greatest earthquakes are generated in subduction zones. Normal faults in subducting plates provide pathways for seawater intrusion, which facilitates mantle serpentinization and consequently triggers seismic activities or large tsunamis. The formation mechanisms of these normal faults need to be better understood to advance the understanding of subduction zone dynamics and ensuring human life safety. This paper reviews the characteristics of normal faults and deformation of subducting plates in the Tonga Trench, Mariana Trench, Izu-Bonin Trench, and Japan Trench in the western Pacific Ocean, describe in quantitative detail the formation of bending-related normal faults through geodynamic modeling. The study finds that the Tonga Trench and Mariana Trench exhibit the largest average fault throws among these subduction systems. The variations in effective elastic thickness of the subducting plate directly influence the distribution of normal faulting region. There is a significant correlation between plate effective elastic thickness and plate age. This paper provides a systematic review of research on the dynamics of the Western Pacific subduction zone and offers insights for future studies in this field.