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根据关东-东海地区1980年1月至1993年4月期间的地震资料,描绘出了菲律宾海板块和欧亚板块之间目前地震平静的边界。关东-东海地区的大多数地震,不是发生在上覆板块(欧亚板块)之内,就是发生在俯冲板块(菲律宾海板块)之中,其震源深度不到30km。菲律宾海板块和欧亚板块之间的板块边界,具有地震活动性水平非常低的特征;也就是,这里的板块边界本身目前处于地震平静状态,发生的地震都是板内地震,或是发生在板块边界的上方,或是发生在板块边界的下方。在东海地区,上覆的欧亚板块内的地震多数都具有压缩轴为EW走向的走滑断裂的特征,而在俯冲的菲律宾海板块内的地震,其特征是压缩轴为NS走向的走滑断裂。在关东地区,大多数地震的特征,是断裂的压缩轴为NW-SE走向。东海和关东两个地区之间的上述差异,被认为是由于板块组构和/或区域应力条件的不同引起的。考虑到本文以及大地测量资料的结果,在10～30km深度的地震平静板块边界表明,在菲律宾海板块和欧亚板块之间有很强的耦合作用,且与震间时段的应变积累一致。
Based on seismic data from January 1980 to April 1993 in the Kanto-Tokai area, the current quake-prone boundary between the Philippine Sea and Eurasian plates is depicted. Most of the earthquakes in the Kanto-Tokai area occur not in the overlying plate (Eurasian plate), but in the subducting plate (Philippine Sea Plate) with focal depth less than 30 km. Plate boundaries between the Philippine Sea and Eurasian plates have very low levels of seismic activity; that is, where the plate boundaries themselves are currently in a quiescence, the earthquakes are either intra-plate earthquakes or occur at Above the plate boundary, or below the plate boundary. In the East China Sea, most of the earthquakes in the overlying Eurasian plate have characteristics of strike-slip faults where the compression axis is EW. In subduction, the earthquakes in the Philippine Sea Plate are characterized by a NS-oriented strike-slip fracture. In the Kanto region, most of the earthquakes are characterized by the NW-SE strike of the fractured compression axis. The above differences between the East China Sea and the Kanto region are thought to be due to differences in tectonics and / or regional stress conditions. Taking into account the results of this paper and the geodetic data, the seismically calm plate boundaries at depths of 10-30 km show strong coupling between the Philippine Sea plate and the Eurasian plate, consistent with the strain accumulation during the period of the earthquake.