Distributed Nubia-Somalia relative motion and dike intrusion in the Main Ethiopian Rift
Distributed Nubia-Somalia relative motion and dike intrusion in the Main Ethiopian Rift
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DOI：
10.1111/j.1365-246x.2006.02904.x
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发表时间：
2006-04-01
影响因子：
2.8
通讯作者：
Klemperer, S.
中科院分区：
文献类型：
--
作者：
Bendick, R.;McClusky, S.;Klemperer, S.
1992-2003年期间，埃塞俄比亚中部的埃塞俄比亚主裂谷（MER）以4.0 +/- 0.9 mm/年（-1）（1 sigma）的平均速率沿裂谷法线方向延伸，几乎是全球板块运动反转估计的张开速率的两倍。裂谷开口附近的大地测量阵列在此期间被容纳在1993年的一个单一的堤防注入事件，空间上与活跃的岩浆段，可能是由观测到的地震活动触发。岩脉注入后，裂谷中的地壳作为层状介质松弛，在10（18）Pa s的粘性半空间上有一个类似于15公里厚的弹性盖。筑堤，而不是裂谷边界断层的正断层，似乎是主要的机制，在MER的扩展，解释了非常低的区域率的时刻释放。地表位移的长度尺度和时间行为要求裂谷中存在粘弹性流变学。
The Main Ethiopian Rift (MER) in central Ethiopia extended in the rift-normal direction at a mean rate of 4.0 +/- 0.9 mm yr(-1) (1 sigma) during the period 1992-2003, nearly a factor of two slower than the opening rate estimated from global plate motion inversions. Rift opening near a geodetic array during this period was accommodated by a single dike injection event in 1993, spatially coincident with active magmatic segments, probably triggered by observed seismicity. Following dike injection, the crust in the rift relaxed as a layered medium, with a similar to 15-km-thick elastic lid over a viscous half space of 10(18) Pa s. Diking, rather than normal faulting on rift-bounding faults, appears to be the predominant mechanism of extension in the MER, explaining the very low regional rates of moment release. The length scale and temporal behaviour of surface displacements require viscoelastic rheology in the rift.