Seismicity, source mechanisms and tectonics of the Azores-Gibraltar plate boundary
Seismicity, source mechanisms and tectonics of the Azores-Gibraltar plate boundary
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亚速尔群岛-直布罗陀板块边界的地震活动、震源机制和构造
DOI：
10.1016/0040-1951(88)90031-5
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
M. Colombas
中科院分区：
文献类型：
--
作者：
E. Buforn;A. Udías;M. Colombas
对从亚速尔群岛到直布罗陀海峡的欧亚大陆和非洲海洋板块边界的地震活动和地震震源机制进行了研究和部分修正。计算了 36 次地震的震源机制、4 次地震的波形模型以及 28 次地震的矩和维数。这些结果表明，边界分为三个具有不同特征的部分：亚速尔群岛、中部部分和东部部分。亚速尔群岛部分地震活动强度中等，滑移率较低（0.76 厘米/年）；主要机制是正断层或转换断层，平均在 N25° E 方向具有水平张力。中部地段发生大地震，伴有沿断层东西向走滑右旋运动；滑移率很高（3.39 厘米/年）。东段性质较为复杂；也有大地震发生，但主要机制是水平压力轴在N30°W方向的逆断层作用，导致非洲俯冲。根据滑移矢量，非洲板块的旋转极点位于北纬 28.2°、西经 21.1°，比之前的位置更靠近边界。靠近大陆，洋壳中延续了伊比利亚半岛的一些结构特征。
A study and partial revision of the seismicity and source mechanisms of earthquakes are presented for the oceanic plate boundary of Eurasia and Africa from the Azores islands to the Strait of Gibraltar. Focal mechanisms of 36 earthquakes, wave-form modelling of 4 and seismic moments and dimensions of 28, have been calculated. These results indicate that the boundary is divided into three sections with different characteristics: the Azores, the Central section and the East section. The Azores section has high seismicity of moderate magnitude and a low slip rate (0.76 cm/yr); the predominant mechanism is normal or transform faulting with horizontal tensions on average in a N25° E direction. In the Central section large earthquakes occur with strike-slip right-lateral motion along faults in an E-W direction; there is a high slip rate (3.39 cm/yr). The East section is of more complex nature; large earthquakes also occur, but the predominant mechanism is reverse faulting with a horizontal pressure axis in the N30°W direction, resulting in underthrusting of Africa. From the slip vectors, the pole of rotation for the African plate is located at 28.2° N, 21.1° W, nearer to the boundary than previous locations. Close to the continent, there is a continuation in the ocean crust of some structural features of the Iberian peninsula.