HR: 08:45h
AN: S41E-04    [Abstracts]
TI: Lithospheric Structure Beneath Ethiopia Using Joint Inversion of Receiver Functions and Surface Wave Group Velocities
AU: * Dugda, M T
EM: mulugeta@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802 United States
AU: Nyblade, A A
EM: andy@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802 United States
AU: Julia, J
EM: jordi@sc.edu
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Ammon, C J
EM: cammon@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802 United States
AB: Lithospheric structure beneath Ethiopia has been imaged using a joint inversion of receiver functions and surface wave group velocity dispersion measurements out to 175 s to determine the extent of lithospheric thinning and heating. Many studies suggest that the lithosphere there may be thermally perturbed. Surface wave data can constrain the average shear wave velocity structure while receiver functions help to constrain the details of the shear wave velocity structure. Data for this study come from the Ethiopia Broadband Seismic Experiment carried out between 2000-2002. We also used data from surface wave studies in Northern Africa and the Middle East, and data from global surface wave studies. The lithosphere beneath the eastern and western sides of the Ethiopian Plateau display similar lid structure with a low mantle shear wave velocity of 4.3-4.4 km/s to depths of about 80 to 110 km. A low velocity zone with shear wave velocity of 4.0-4.2 km/s is observed below the mantle lid. Under the Main Ethiopian Rift (MER), no clear lid structure is observed but a low shear wave velocity of 4.0-4.2 km/s is found from the Moho to about 150 km depth. Similar to the MER, the lithosphere beneath Afar shows no clear lid structure, but a low shear wave velocity of about 4.0 km/s is observed beneath the Moho to about 160 km depth. As compared to the shear wave velocity for the lithosphere beneath unrifted parts of the Mozambique Belt in eastern Africa, the lithosphere beneath Ethiopia appears to be thermally perturbed throughout its thickness.
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
DE: 1734 Seismology
DE: 3621 Mantle processes (1038)
DE: 7218 Lithosphere (1236)
DE: 9305 Africa
SC: Seismology [S]
MN: Fall Meeting 2005