1. School of Geosciences, Monash University, Melbourne, Vic. 3800, Australia.
2. Corresponding author.
3. Civil Engineering Department, Middle East Technical University, 06800 Cankaya, Ankara, Turkey.
4. Faculty of Engineering, Ankara University, 06100 Tandogan, Ankara, Turkey.
5. Present address: Ministry of Environment and Urbanization, General Directorate of Spatial Planning, Department of Geoscience Surveys, Ankara, Turkey.
6. Present address: Civil Engineering Department, Stanford University, Stanford, CA 94305-4121, USA.