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用震源机制和地震活动性方面的资料研究了伊比利亚和非洲的板块边界。该地区可以被分为三个区:A区,加的斯湾;B区,贝蒂克山、阿尔沃兰海和摩洛哥北部;C区,阿尔及利亚。地震活动的特征很复杂,浅源(震源深度h<30km)大地震发生在A区和C区,中等地震发生在B区;中深源(震源深度h=30～150km)的地震发生在B区;深源地震(震源深度h≈650km左右)发生在格拉纳达以南。浅源地震的地震矩率、滑动速度和6值的估算表明在加的斯湾和阿尔及利亚地区有相似的特征·而在中部地区却大不相同。所选的80个浅源地震(8≥m_b≥4)的震源机制表明,在加的斯湾和阿尔及利亚地区是逆)中断裂,水平挤压的方向是NNW—SSE向,而在阿尔沃兰海是在东西向水平张力作用下形成的正断裂。阿尔沃兰海26个中深源地震的震源机制显示的是垂直运动机制,优势面为东西向。极深地震的震源机制解与沿南北向的垂直倾滑运动一致。Frohlich图和地震矩张量显示,在加的斯湾、贝蒂克山—阿尔沃兰海和摩洛哥北部地区以及阿尔及利亚北部地区的浅源地震特征是不同的。中等深度地震和极深地震的应力图象有着不同的方向:中等深度地震为NW—SE向垂直拉伸,极深地震的张应力轴和压应力轴的倾角约为45°。区域应力图象可能是由非洲板块和伊比利亚板块之间的碰撞引起的,使得岩石层物质在阿尔沃兰海中等深度的地方扩张和俯冲。极深地震的活动可能与更老的俯冲过程有关。
The plate boundaries of Iberia and Africa were studied using data on focal mechanisms and seismicity. The area can be divided into three areas: Area A, Bay of Cadiz; Area B, Beethuk, the Arvoran Sea and northern Morocco; Area C, Algeria. The characteristics of seismic activity are very complicated. The large earthquakes with shallow source depth (h <30km) occur in areas A and C, the moderate earthquakes occur in area B, the earthquakes with medium depth source (depth h = 30-150km) occur in B Area; deep source earthquake (focal depth h ≈ 650km or so) occurred in south of Granada. Estimates of seismic moment rates, slip velocities and 6-values for shallow earthquakes show similar characteristics in the Bay of Cadiz and Algeria, but in the central region. The focal mechanism of the selected 80 shallow earthquakes (8 ≥ m_b ≧ 4) shows that it is inversed in the Gulf of Cadiz and the Algerian region) and the direction of horizontal crushing is NNW-SSE, whereas in Alvor The sea is a normal fault formed by the horizontal tension of the east-west. The focal mechanism of the 26 mid-deep earthquakes in the Alvor Lanhai shows a vertical movement mechanism with the dominant surface orientated east-west. Focal mechanism solutions for extremely deep earthquakes are consistent with vertical dumping along the north and south. The Frohlich plots and seismic moment tensor show different features of shallow earthquakes in the Gulf of Cadiz, the Beethuk Mountains-Northern Albania and northern Morocco, as well as in northern Algeria. The stress images of moderate-depth earthquakes and deep earthquakes have different orientations: moderate-depth earthquakes stretch NW-SE vertically, and dip of dip-stress and compressive stress axes of deep earthquakes is about 45 °. The regional stress image may be caused by the collision between the African plate and the Iberian plate, causing the lithospheric material to expand and subduct at moderate depths in the Alvor Sea. Earthquakes may be related to older subduction processes.