Title: Seismicity, source mechanisms and tectonics of the Azores-Gibraltar plate boundary
Abstract: 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.
Publication Year: 1988
Publication Date: 1988-09-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 254
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