Fig. 1: Two main forcing scenarios for SZI development.
From: Horizontally forced initiation of the Izu-Bonin-Mariana subduction zone
a, b Vertically forced scenario: After the thinning and weakening of the future upper plate, the oceanic plate’s negative buoyance leads to SZI10. Note that tectonic loading may also aid SZI, and like negative buoyancy, its direction is mainly vertical2,19. c, d Horizontally forced scenario: Horizontal force (or plate push) overcomes the resistance from the future upper plate and triggers SZI8,25,29. e Stage of mature subduction. This stage features horizontal mantle wedge flow, sparse arc magmatism, and serpentinites developed in the subducting lithospheric mantle or eroded from the forearc mantle as the slab’s main dehydration components29,37,39,47. The decoupling zone could be the junction between compositionally/rheologically different tectonic blocks that favor strain localization8,66. The initial condition in this cartoon figure specifically targets an Izu–Bonin–Mariana-type SZI development we mainly simulated in this study. The reader should check more SZI scenarios in the literature, e.g., Crameri et al.9.
