3D geometric modelling of the Northwest Pacific slabs: A review and new high-precision model

The Northwest Pacific subduction zone has undergone a complex tectonic evolution accompanied by intense seismic activity. Understanding the morphology of the subducting slabs can help to unravel the subduction history and suggest guidance for present-day tectonic events. Various studies, including numerous tomographic surveys, have imaged the subducting slabs in increasing detail. 2D sections do not provide a detailed picture of the local structure and leave open the possibility of misjudgment. For this reason, we reviewed the slab geometric modelling methods and proposed a new interpretation process to construct an improved and integrated 3D geometry model of the Northwest Pacific subducting slabs. Our model integrates available regional/global tomographic data and earthquake hypocenters, combined with plate tectonic boundaries and regional seafloor tomography, to reveal the morphology, extent of extension, and especially the local structure of the subducting slabs. The subducting Pacific slabs exhibit a significant variation from north to south over the Kuril-Japan-Izu-Bonin-Mariana Island arc, with a pattern of high-low-high-vertical changes in the subduction dip. The stagnant Pacific slab in the mantle transition zone extends westward as far as eastern China. Localized smaller structures including gaps, tears, and segments, emerged in the constructed model, which may correspond to key tectonic features that require further exploration. Our new high-resolution model contains a wider and deeper range and more details than traditionally used geometry models (e.g., Slab2.0), despite of exhibiting similar subduction trends. Our integrated geometry model can contribute to a better understanding of the tectonics and seismic-volcanic activity of the Northwest Pacific subduction zone.