HR: 0830h
AN: S51C-0073    [PDF]
TI: Deformation Distribution and Type in the Main Ethiopian Rift
AU: * Kurz, T
EM: tkurz@student.tu-freiberg.de
AF: TU "Bergakademie" Freiberg, Institut fuer Geologie B. von Cotta Strasse 2, Freiberg, 09599 Germany
AU: Gloaguen, R
EM: gloaguen@geo.tu-freiberg.de
AF: TU "Bergakademie" Freiberg, Institut fuer Geologie B. von Cotta Strasse 2, Freiberg, 09599 Germany
AU: Ebinger, C
EM: c.ebinger@gl.rhul.ac.uk
AF: Royal Holloway University of London, Geology Department, Egham, TW200EX United Kingdom
AU: Casey, M
EM: m.casey@earth.leeds.ac.uk
AF: University of Leeds, School of Earth Sciences, Leeds, LS29JT United Kingdom
AU: Abebe, B
EM: bekelino@yahoo.com
AF: University of Addis Ababa, Department of Geology and Geophysics, Addis Ababa, PO1176 Ethiopia
AB: The Main Ethiopian Rift central graben is magmatically segmented and seismically active. These magmatic segments are about 50 km long and up to 20 km wide, oriented about N10-20, and therefore oblique to the main direction of Mid-Miocene border faults (N35E). We use the association of the high spectral resolution of Landsat data and the very high spatial resolution of digitized aerial photographs to characterize and quantify the deformation along the rift. Several Digital Elevation Models of metric resolution have been produced at different locations along the segments in order to quantify and describe the fault deformation. We have analysed the Landsat data (texture analysis, PCA, classifications) in order to refine the existing geological maps and to propose a relative chronology of the deformation. The deformation within the segments varies from their centres, usually highly faulted and mainly rhyolitic and trachytic calderas (Gedemsa, Bosetti, Fantale, Dofan ), to their tips where the deformation is brittle at the surface and associated to recent basaltic flows and aligned cones. There we propose that the atypical (by their morphologies and Displacement/Length ratios) faults are dyke induced (see Gloaguen et al., same session). The overlap of the segments, the cross-cuttings of faults on the rift margins and the associated seismic activity are in agreement with the longitudinal growth of the magmatic segments via along-axis magma injection.
DE: 8010 Fractures and faults
DE: 8040 Remote sensing
DE: 8105 Continental margins and sedimentary basins
SC: Seismology [S]
MN: 2003 Fall Meeting