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Shear waves velocities in the upper mantle structure beneath the Afar Hotspot
by
Jamal M. Sholan
Director, National Seismolgical Obsevatory Center - Yemen
Coauthors: Sicilia D. (IPGP), Montagner J.C. (IPGP), Debayler E. (University of Louis Pasteur), Cara M. (University of Louis Pasteur), Leveque J.J. (University of Addis Ababad), Lepine J.C. (IPGP), Beucler E. (IPGP), Sebai A. (IPGP), Ayele A. (University of Addis Ababa)
The Afar area is one of the biggest continental hotspots and may be the surface expression of mantle plume related to the African Superswell. The origin at depth of mantle plumes is still controversial and their interaction with lithosphere and crust remain unclear. Data have been collected from the global seismological permanent FDSN networks (GEOSCOPE. IRIS, MedNet, Geofon, etc.). We also used data from the temporary PASSCAL experimental in Tanzania and Saudi Arabia and completed our data set with a France deployment of 5 portable broadband stations surrounding the Afar Hotspot and equipped with STS-2 seismometers. Three of them were installed in Ethiopia and two others in Yemen. A classical two-step tomographic inversion from surface wave has been performed in the Horn of Africa with 1764 Rayleigh wave and 744 Love wave seismograms. Path average phase velocities are obtained by using the recently published non-liner roller coaster waveform inversion method. The simultaneous inversion of Rayleigh and Love wave fundamental modes enables us to present 3D-model of both Sv velocities and azimuthal anisotropy, together with radial SH /SV anisotropy. The region is characterized by low shear-wave velocities beneath the Afar Hotspot, the Red Sea, the Gulf of Aden and East of the Tanzania Craton. The results of this study enable us to rule out a possible feeding of the Central Africa hotspots from the Afar plume above 150-200km.
Date received: August 1, 2004
Copyright © 2004 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caon-23.