Juan Li Guangrui Guo Walter D. Mooney Shun-Ichiro Karato David A. Yuen Guangjie Han 2021 <p><span>Regional triplication waveforms of five intermediate-depth events are modeled to simultaneously obtain the compressional (P) and shear (SH) wave velocity structure beneath northwestern Pacific&nbsp;subduction zone. Both the P- and SH-wave velocity models for three different sub-regions show a low-velocity layer (LVL) with a thickness of ∼55-80 km lying above the 410-km discontinuity with a ∼900 km lateral extent from the Japan Sea to the northeastern Asian&nbsp;continental margin. With the dihedral angle approaching to zero around 400 km, a minute amount of melt atop the 410-km discontinuity caused by the hydrous slab might completely wet olivine grain boundaries and result in a low&nbsp;</span>seismic velocity<span>&nbsp;layer in this specific&nbsp;subduction zone. This mechanism suggests that the 410-LVL is a low viscosity zone that would partially decouple the&nbsp;upper mantle&nbsp;from the transition zone. We infer that the widespread 410-LVL provides evidence for a water-bearing mantle transition zone beneath the western Pacific subduction zone.</span></p> application/pdf 10.1016/j.epsl.2020.116642 en Elsevier Pervasive low-velocity layer atop the 410-km discontinuity beneath the northwest Pacific subduction zone: Implications for rheology and geodynamics article