The Philippine Sea (PHS) plate subducts beneath the Eurasian plate at the Suruga Trough where megathrust earthquakes have repeatedly occurred. We used data from permanent seismic stations on land and temporary seismic stations beneath Suruga Bay to resolve the seismic velocity structure from the surface to 40–60 km depth beneath the Tokai region. The Median Tectonic line runs through the Tokai region and forms a boundary between high-V and low-V zones. We constrained the configuration of the subducting PHS plate using results from seismic tomography, hypocentral distribution of microseismicity, and low-angle thrust-type earthquakes. The oceanic crust of the PHS plate is characterized by low-V and high-Vp/Vs values. Events with thrust-type focal mechanisms are expected at the plate boundary. We constructed the geometry of the surface of the subducting PHS plate using this information. This geometry is also consistent with the results of receiver functions. The surface of the PHS plate is slightly (approximately 6–10 km) shallower than estimated from previous studies, especially in the zone extending from the Suruga Trough to a depth of 20 km. The data combination of permanent land and temporary OBS station with rays crossing the plate boundary clarify the plate configuration at the shallow subduction zone.

菲律宾海 (PHS) 板块在骏河海槽处俯冲到欧亚板块之下，那里曾多次发生过大地震。我们使用来自陆地永久地震台站和骏河湾下方临时地震台站的数据来解析从地表到东海地区下方 40-60 公里深度的地震速度结构。中间构造线贯穿东海地区，形成高 V 区和低 V 区之间的边界。我们使用地震层析成像、微震震源分布和低角度逆冲型地震的结果来限制俯冲 PHS 板块的构造。PHS 板块的洋壳具有低 V 和高 Vp/Vs 值的特征。预计在板块边界会发生具有推力型震源机制的事件。我们使用这些信息构建了俯冲 PHS 板块表面的几何形状。这种几何形状也与接收器函数的结果一致。PHS 板块的表面比先前研究估计的略浅（约 6-10 公里），特别是在从骏河海槽延伸至 20 公里深度的区域。永久陆地和临时 OBS 站的数据结合，射线穿过板块边界，明确了浅俯冲带的板块构造。