HR: 14:55h
AN: T53E-06    [Abstracts]
TI: Along-axis Segmentation of the Main Ethiopian Rift from Tomographic Inversion of Local Earthquakes
AU: * Daly, E
EM: e.daly@nuigalway.ie
AF: Earth and Ocean Sciences, National University of Ireland, Galway, City Ireland
AU: Ebinger, C
EM: c.ebinger@gl.rhul.ac.uk
AF: Geology Department, Royal Holloway University of London, Egham, TW20 0EX United Kingdom
AU: Stuart, G
EM: graham@earth.leeds.ac.uk
AF: School of Earth Sciences, University of Leeds, Leeds, LS2 9JT United Kingdom
AU: Keir, D
EM: d.keir@gl.rhul.ac.uk
AF: Geology Department, Royal Holloway University of London, Egham, TW20 0EX United Kingdom
AU: Ayele, A
EM: atawon@yahoo.com
AF: Geophysical Observatory, Addis Ababa University, Addis Ababa, AA Ethiopia
AU: Waltham, D
EM: d.waltham@gl.rhul.ac.uk
AF: Geology Department, Royal Holloway University of London, Egham, TW20 0EX United Kingdom
AB: Geophysical, structural, and geochemical data indicate that the East African rift system in Ethiopia is in a stage of development transitional between continental and oceanic spreading. In the northern Main Ethiopian rift (MER) the archetypal continental rift stage border fault systems bounding the asymmetric rift basins formed at ~11 Ma. After 3.5 Ma, strain localised to fault systems within the central basin. By 1.8 Ma, faulting and magmatism localised to an en echelon series of 20 km-wide zone, 50-60 km-long 'magmatic segments' comprising felsic shield volcanoes and basaltic fissural flows and dikes. As part of the international EAGLE project, 50 broadband Guralp 6TD seismometers were deployed across 3 magmatic segments, and a sector of the rift without magmatic segments. These instruments nested within the Leeds University broadband array, and the combined net of 80 instruments was used to locate local and regional events. P wave inversion for velocity with a series of synthetic tests will be presented at the meeting along with the best 1d velocity model for locating local earthquakes within the Main Ethiopian rift. Results indicate a series of high velocity zones beneath the magnetic segments at a depth of 10km.
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7280 Volcano seismology (8419)
DE: 8109 Continental tectonics: extensional (0905)
DE: 8178 Tectonics and magmatism
DE: 8180 Tomography (6982, 7270)
SC: Tectonophysics [T]
MN: Fall Meeting 2005