Descr: We plan to participate in an international geophysical effort (East African Geophysical Lithospheric Experiment – EAGLE) focused study the Ethiopian rift. By linking our effort with a funded project by a consortium of British universities and cooperating with ongoing U. S. (Penn State) and French passive seismic studies, we will be able to use a combination of passive and controlled source seismic experiments to determine the geometry and kinematics of a continental rift as it evolves from a classic rift valley geometry to an expanded geometry reflecting the situation immediately prior to break-up. The Ethiopian rift and Afar are an ideal natural laboratory because 1) this rift sector preserves the initial rift geometry and has zones of incipient seafloor spreading, allowing us to trace rift evolution; 2) geodetic data place bounds on the distribution of strain and lithospheric rheology; 3) the logistics of the study area are tractable (it encompasses the Ethiopian capital); 4) geothermal exploration data suggest shallow magma reservoirs; and 5) seismic data acquisition funded by the US (Ethiopia; Red Sea), ODP (Gulf of Aden), France (Yemen, Gulf of Aden), and Kenya (KRISP) will provide a regional geodynamic context in which we may interpret our more detailed study of break-up processes.
