Post-diking Response to the Sept-Oct. 2005 Boina Event, Afar Depression, Ethiopia

北部阿法尔凹陷是一块现代洋底，其形态特征与在缓慢扩张的大洋中脊上观察到的相似。我们知道，大洋中脊的构造板块之间的分离主要是由垂直岩浆片或岩浆岩的幕式侵入造成的。然而，人们对它们的侵位过程知之甚少，因为大多数大洋扩张中心都位于水下2-3000米以下，这使得直接观测变得极其困难和昂贵。2005年9月14日至11月5日，在阿法尔发生了一次大规模的裂谷事件，埋设了一条60公里长的堤坝，开口最大可达8米。这是自1783年冰岛拉基火山喷发以来，陆地上已知的最大的单一裂谷事件，也是卫星大地测量时代第一次发生。该项目将使用全球定位系统对堤防事件之后的地表运动进行连续观测，以更好地了解控制海底形成的机制。我们的结果还将有助于评估与Gabho裂谷有关的危险，并为地方当局提供作出人口迁移决定所需的科学数据。

The northern Afar depression is a piece of recent ocean floor with morphological characteristics similar to those observed at slow-spreading mid-oceanic ridges. We know that the separation between tectonic plates at mid-oceanic ridges is mostly accounted by episodic intrusions of vertical sheets of magma, or dikes.The processes that govern their emplacement is however poorly understood since most oceanic spreading centers lie under 2-3 thousand meters of water, making direct observations extremely difficult and expensive. Between September 14 and November 5 2005, a massive rifting event took place in Afar, with the emplacement of a 60 km long dike with up to 8 m of opening. It is the largest single rifting event known to have occurred on land since the Laki (Iceland) eruption in 1783, and the first to occur in the era of satellite geodesy. This project will use continuous GPS observations of surface motions followingthe diking event to better understand the mechanics that governs the formation of oceanic floor. Our results will also serve to assess the hazard associated with the Gabho rift and provide the local authorities with scientific data needed to make decisions on population relocation.