Seismic Structure of the Transition Zone Associated with the Japanese Subduction Zones

9526678田岛这项研究是调查400至700公里深的上地幔过渡带的地震结构，这是了解地幔内部对流模式以及地球化学成分的关键。在这个项目中，该计划将利用区域台站记录的上地幔P波和S波来圈定与日本俯冲带有关的过渡带的地震结构。最近讨论的三个主要问题将被考虑：1)什么速度异常与过渡带中的俯冲带有关；2)俯冲板块是在过渡带底部变平还是延伸到下地幔；以及3)上地幔的地震结构是否支持化学分层模型或由于温度相关的相变而产生的间断模型，大约在410公里左右，可能在大约525公里处。*？？

9526678 Tajima This research is to investigate the seismic structure of the upper mantle transition zone, from 400 to 700 km depth, which is key to understanding the mode of convection within the Earth's mantle as well as the chemical composition of the Earth. In this project, the plan will be to delineate seismic structure of the transition zone associated with Japanese subduction zones using upper mantle (triplicated P and S waveforms recorded at regional stations. Three major issues debated recently will be considered: 1) what velocity anomalies are associated with the subduction zones in the transition zone; 2) whether the subducting slabs flatten at the bottom of the transition zone or extend into the lower mantle; and 3) whether the seismic structure derived for the upper mantle supports a model of chemical layering or one with discontinuities due to temperature-dependent phase transitions approximately at 410 km, and possibly at about 525 km. *** ??