The Afar triple junction accommodation zone from InSAR derived strain and seismicity

Abstract:

Strain and seismicity show us the mode by which deformation is accommodated in rifting continents. Here we present a combined analysis of InSAR derived strain maps and seismicity of the Afar triple junction from 2006 to 2010. Our analysis shows that that the plate spreading motion is accommodated in different modes. A dogbone-shaped seismicity and strain distribution dominates the northern Red Sea branch of the triple junction, likely as a result of repeated dike intrusions 2005-2010. East of the triple junction, in the Gulf of Aden branch the strain and seismicity distribution appears decoupled. The strain focuses across the central part of several overlapping rifts, while the seismicity mainly occurs at the rift tips. Conversely, the Main Ethiopian Rift branch shows a narrow and elongated zone of both high strain and seismicity. The pattern suggests that the recent history of magmatic intrusions in the northern branch and mainly tectonic extension in the other branches creates a diverse triple junction accommodation zone.