HR: 13:40h
AN: S52G-01    [PDF]
TI: Deep Upwelling Beneath the Northeastern Afro-Arabian Continent?
AU: * Cara, M
EM: Michel.Cara@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue R. Descartes, Strasbourg, F67084 France
AU: Wittlinger, G
EM: Gerard.Wittlinger@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue R. Descartes, Strasbourg, F67084 France
AU: Debayle, E
EM: Eric.Debayle@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue R. Descartes, Strasbourg, F67084 France
AU: Sieminski, A
EM: Anne.Sieminski@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue R. Descartes, Strasbourg, F67084 France
AU: Montagner, J P
EM: jpm@ipgp.jussieu.fr
AF: IPGP-Dpt.Seismology, Case 89 4, Place Jussieu, Paris-cedex05, F75252 France
AU: Lepine, J C
EM: lepine@ipgp.jussieu.fr
AF: IPGP-Dpt.Seismology, Case 89 4, Place Jussieu, Paris-cedex05, F75252 France
AB: A large low shear-wave velocity anomaly is observed at upper-mantle depths beneath the northeastern Afro-Arabian continent, from the Turkana depression, South-West of Ethiopia, to the Red sea and South of Arabia. The question of connection between this anomaly and a source of material rising from the lower mantle is of major concern for understanding how a plume associated with the African superswell could interact with the upper mantle structure in the region. Thanks to the deployment of five broadband stations in Ethiopia and Yemen (INSU-RLBM), complementing several sets of broad-band stations in Arabia, Ethiopia and Djibouti (IRIS, Geoscope, PASSCAL) we address this question by using two broadband seismological tools: 1) higher-mode surface wave tomography and 2) receiver function technique. Higher-mode surface waves tomography shows a clear low shear-wave velocity anomaly down to 400 km depth beneath the Ethiopian plateau and the Afar depression. In a paper by Debayle et al. (2001), no continuity of this anomaly with a deeper low-velocity anomaly is observed beneath Ethiopia. Instead, a deeper low-velocity anomaly (down to ~500-600 km depth) was observed farther north beneath the Red Sea and South of Arabia, suggesting a possible link with lower mantle material rising there. Applying a SVD receiver function technique to a set of broad-band records from Arabia to Ethiopia, including Yemen, we discuss the above suggestion by looking at the seismic discontinuities of the upper-mantle transition zone.
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8180 Tomography
SC: Seismology [S]
MN: 2003 Fall Meeting