1. Department of Geology and Geophysics, University of Addis Ababa
PO Box 176, Addis Abada, Ethiopia
yirgu.g@geol.aau.edu.et
2. Department of Geology, Royal Holloway, University of London
Egham, TW20 0EX, UK
c.ebinger@gl.rhul.ac.uk
3. Department of Geology, University of Leicester
Leicester LE1 7RH, UK
pkm@le.ac.uk