SEMINAR - Jill Pearse

Post-rifting deformation in Afar, Ethiopia, following the 2005 intrusion event

Jill Pearse
Scripps Institution of Oceanography
University of California, San Diego

April 15th, 2009

The 300-km wide Afar depression is located at the junction between the Red Sea, Gulf of Aden and East African rifts. In September and October of 2005, a series of large earthquakes and a volcanic eruption signaled the intrusion of a dike along the Dabbahu magmatic segment (in the Red Sea arm) of the Afar rift. Results of elastic modeling constrained by InSAR (Wright et al 2006) data suggest that the 60-km long segment opened by up to 8 m, between depths of 2-9 km. Relaxation of stresses in the crust below the brittle-ductile transition following the intrusion event should create geodetically observable surface deformation, however this signal can be obscured by continuing active intrusions. Using 3-D finite element models, we predict the surface deformation following the 2005 Dabbahu event for a range of crustal and mantle rheologies. We compare our model results to InSAR data spanning the 3 years since the intrusion to quantify the post-rifting deformation and place constraints on the rheology below the brittle-ductile transition in Afar.