摘要
利用ISC及中国台网的资料,研究了琉球岛弧及冲绳海槽的地震分布及震源机制解,讨论了Benioff带的形态及应力状态.m_b≥4.0的地震主要分布于琉球海沟西侧的弧形带,并形成明显的Benioff带.吐噶喇海峡以北俯冲带弯曲明显,深部倾角大,约92°,70km以下张应力轴沿俯冲方向;吐噶喇海峡以南,俯冲带较平直,深部倾角较小,约55°,压应力轴基本沿俯冲方向。冲绳海槽内处于NNW向近水平的拉伸,华北应力场与之类似,没有受到菲律宾海块挤压作用的影响.
The distribution and focal mechanisms of earthquakes from 1966 to 1982 in the Ryukyu island arc and the Okinawa trough were studied using the data from I. S. C. and the network of Chinese seismological stations. The behavior of the subduction zone and the stress state were discussed. The earthquakes of mb≥4.0 distribute mainly in an arc-like narrow belt in the west side of the Ryukyu trench and form a clear Benioff zone beneath the island arc. To the north of the Tokara channel, the subduction zone curves heavily, the dip angle is steep in the lower part, about 72°; The axes of the principal tension stress are in the subduction plane, mainly coincide with the subducting direction and the axes of the principal compression stress are nearly horizontal below 70 km. To the south of the Tokara channel, the dip angle of the subduction zone is smaller, about 55°, in the lower part; The axes of the principal compression stress are mostly in the subducting plane and most of the axes of the principal tension stress are nearly horizontal below 90 km. It seems that there is a double seismic zone on the subduction zone.In the Okinawa trough, the axes of principal tension stress are in the NNW direction and nearly horizontal, the axes of the principal compression stress appear to be in the NEE direction. The stress state in northern part of China is similar to that in the Okinawa trough, there is no compression effect from the Philipping sea plate on the northern part of China.
出处
《地震学报》
CSCD
北大核心
1989年第2期113-123,共11页
Acta Seismologica Sinica
