HR: 0800h
AN: T41A-0382    [Abstracts]
TI: Comparison of the Lithospheric Structure Beneath Kenya and Ethiopia From Joint Inversion of Receiver Functions and Rayleigh Wave Dispersion Velocities
AU: * Dugda, M T
EM: mtdugda@ncat.edu
AF: Department of Physics, North Carolina A & T State University, Greensboro, NC 27411, United States
AU: Nyblade, A A
EM: andy@geosc.psu.edu
AF: Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States
AU: Julia, J
EM: jordi@seis.sc.edu
AF: Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States
AB: Shear-wave velocity structure of the crust and upper mantle beneath Kenya has been investigated using joint inversion of receiver functions, and Rayleigh wave group and phase velocities. Most of the data for this study come from the Kenya broadband seismic experiment, conducted between 2001 and 2002. Shear velocity models obtained from the joint inversion show crustal thicknesses of 37 to 42 km beneath the East African Plateau in Kenya and near the edge of the Kenya Rift, and a crustal thickness of about 30 km beneath the Kenya Rift. These crustal parameters are consistent with crustal thicknesses published previously by different authors. A comparison has been made between the lithosphere under Kenya and other parts of the East African Plateau in Tanzania. A comparison between the lithosphere under Kenya and that under Ethiopia has also been made, specifically between the lithosphere under the Ethiopian Plateau and the Kenya Plateau, and between the lithosphere beneath the Main Ethiopian Rift (MER) and the Kenya (Gregory) Rift. The lithospheric mantle beneath the East African Plateau in Kenya has a maximum shear wave velocity of about 4.6 km/s, similar to the value obtained under the East African Plateau in Tanzania. Beneath the Kenya Rift, the lithosphere extends to a depth of at most ~75 km. The average velocity of the mantle lithosphere under the East African Plateau in Kenya appears to be similar to the lithosphere under Tanzania away from the East African Rift System. The lithosphere under the Kenya Plateau is not perturbed as compared to the highly perturbed lithosphere beneath the Ethiopian Plateau. The lithosphere under the Kenya Rift is perturbed as compared to the rest of the region but is not as perturbed as that under the Main Ethiopian Rift or the Afar. Though Kenya and Ethiopia have similar uplift, volcanism and rifting at the surface, they have different lithospheric structures at the bottom. The Afar Flood Basalt Volcanism (AFB) may be the cause of this striking difference in the two lithosphere.
DE: 0905 Continental structures (8109, 8110)
DE: 1212 Earth's interior: composition and state (7207, 7208, 8105, 8124)
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere (1236)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting