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 following the 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.
