Collision and fan‐shaped compressional stress pattern in the Izu Block at the northern edge of the Philippine Sea Plate
Collision and fan‐shaped compressional stress pattern in the Izu Block at the northern edge of the Philippine Sea Plate
复制标题
菲律宾海板块北缘伊豆地块的碰撞和扇形压应力模式
DOI：
10.1029/90jb02142
复制
发表时间：
1991
影响因子：
--
通讯作者：
M. Ukawa
中科院分区：
文献类型：
--
作者：
M. Ukawa
位于日本中部的伊豆地块被南开-Suruga海槽和佐贺海槽包围，被认为在菲律宾海(PHS)板块的北缘与欧亚(EUR)板块碰撞。伊豆地块的应力状态是根据国家地球科学与灾害预防研究所地震台网主要获得的震源机制数据进行研究的。伊豆地块中东部的主要震源机制为走滑断裂，P轴为N-S向NW-SE，T轴为E-W-SE向，西部为走滑和逆断层，P轴为N-S-NE-SW，表明挤压轴在全区保持水平。从P轴估计的挤压应力轨迹显示为扇形图案，从被认为发生碰撞的伊豆地块北缘辐射。这种扇形的挤压应力轨迹被解释为伊豆地块与欧洲板块碰撞的结果。有限元平面应力分析支持这一结论。T轴方向在中部和东部的稳定分布基本上被解释为是俯冲的PHS板块沿Sagami海槽俯冲的板片拉力的结果。此外，该模型还可以解释苏鲁加湾北部的地震平静现象。
The Izu block in central Japan, which is surrounded by the Nankai-Suruga trough and the Sagami trough, is considered to be colliding with the Eurasian (EUR) plate at the northern edge of the Philippine Sea (PHS) plate. The stress state in the Izu block is investigated from focal mechanism data mainly obtained by the seismic network of the National Research Institute for Earth Science and Disaster Prevention. The predominant focal mechanisms in the central to eastern part of the Izu block indicate strike-slip faulting with P axes oriented N–S to NW–SE and T axes oriented E–W to NE–SW, whereas focal mechanisms in the western part are strike-slip and reverse faulting with P axes oriented N–S to NE–SW, indicating that the compressional axes remain horizontal throughout the region. The compressional stress trajectories estimated from the P axes show a fan-shaped pattern, radiating from the northern edge of the Izu block where the collision is considered to be occurring. The fan-shaped pattern of compressional stress trajectories is interpreted to be the result of the collision of the Izu block with EUR plate. Plane stress analysis by the finite element method supports this conclusion. The stable distribution of the T axis directions in the central to eastern part is basically interpreted as resulting from the slab pull force by the subducting PHS plate along the Sagami trough. Furthermore this model can explain the seismic quiescence in the northern part of the Suruga Bay region.