Document Type : Original Research Paper


1 Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran

2 Islamic Azad University (IAU), North Tehran Branch, Tehran, Iran Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran


Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics.These indices have the advantage of being calculate from ArcGIS and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics.This is particulary valuable in west-central Alborz where relatively little work on active tectonics based on this method was done,so this method is new and useful. Based upon values of the stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), and index of mountain front sinuosity (Smf),we used an overall index(Iat) that is a combination of the other indices that divides the landscape into four classes of relative tectonic activity. The moderat class of Iat is mainly in the south of Manjel dam,while the rest of the study area has high active tectonics (shahrud drainage basin and sefidrud drainage basin),and high to very high(Taleghan and Alamut drainage basin). The stream network asymmetry (T)was also studied using morphometric measures of Tranverse Topographic Symmetry.Analysis of the drainage basins and subbasins in the study area results in a field of T-vectors that defines anomalous zone of the basin asymmetry.Acomparsion of T index clearly coincide with the values and classes of active tectonics indices and the overall Iat index.


Asserto, R., 1966- Geological Map of upper Djadjerud and Lar Valleys (Central Elburz, Iran). Institute of Geology, University of Milan, scale 1:50,000.
Burbank, D. W. and Anderson, R. S., 2001- Tectonic Geomorphology. Blackweel Science, Massachusetts.
Cox, R. T., 1994- Analysis of drainage- basin symmetry as a rapid technique to identify areas of possible Quaternary tilt-block tectonics: An example from the Mississippi Embayment. Geological Society of America Bulletin ,106, 571-581.
Ritz, J. F., Nazari, H., Ghassemi, A., Salamati, R., Shafei, A., Solaymani, S. & Vernant, P., 2006- Active transtension inside Central Alborz: A new insight into northern Iran-southern Caspian geodynamics. Geological Society of America ,34, 477-480.
 Stöcklin, J., 1974- Northern Iran: Alborz Mountains. In: Spencer, A. (Ed.). Mesozoic–Cenozoic Orogenic Belts: Data for Orogenic Studies. Geological Society Special Publication, London 4, pp. 213–234.
Yousefi, E. & Fridborg, J. L., 1978- Aeromagnetic map ofQazvin, Gelogical Survey of Iran, Qazvin- Scale1:250000
Alavi, M., 1996- Tectonostratigraphic synthesis and structural style of the Alborz mountain system in northern Iran. Journal of Geodynamics ,21, 1–33.
Allen, M. B., Ghassemi, M. R., Shahrabi, M. & Qorashi, M., 2003- Accommodation of Late Cenozoic oblique shortening in the Alborz Range, Northern Iran. Journal of Structural Geology, 25 (5), 659–672.
Azor, A., Keller, E. A. and Yeats, R. S., 2002- Geomorphic indicators of active fold growth: South Mountain-Oak Ridge Ventura basin, southern California. Geological Society of America Bulletin ,114, 745-753.
Bull, W. B., 1978- Geomorphic Tectonic Classes of the South Front of the San Gabriel Mountains, California. U.S. Geological Survey Contract Report, 14-08-001-G-394, Office of Earthquakes, Volcanoes and Engineering, Menlo Park, CA.
Bull, W. B. and McFadden, L. D., 1977- Tectonic geomorphology north and south of the Garlock fault, California. In: Doehring, D. O (eds), Geomorphology in Arid Regions. Proceedings of the Eighth Annual Geomorphology Symposium. State University of New York, Binghamton, pp. 115-138.
Cannon, P. J., 1976- Generation of explicit parameters for a quantitative geomorphic study of Mill Creek drainage basin. Oklahoma Geology Notes, 36(1), 3-16.
EL Hamdouni, R., Irigaray, C., Fernandez, T., Chacon, J. and Keller, E. A., 2007- Assessment of relative active tectonics, southwest border of the Sierra Nevada (southern Spain). Geomorphology. Article in press.
Guest, B., Axen, G. J., Lam, P. S. &  Hassanzadeh, J., 2006- Late Cenozoic shortening in the west-central Alborz Mountains, northern Iran, by combined conjugate strike-slip and thin-skinned deformation, Geosphere 2/1: 35-52. vin, Scale 1:250000.
Hack, J. T., 1973- Stream-profiles analysis and stream-gradient index. Journal of Research of the U.S. Geological Survey 1 (4), 421-429.
Hare, P. H. & Gardner, T. W. M., 1985- Geomorphic indicators of vertical neotectonism along converging plate margins, Nicoya Peninsula, Costa Rica, In Tectonic Geomorphology, Morisawa, M, Hach, J. T (eds). Allen and Unwin, Boston, 75-104.
Keller, E. A., 1986- Investigation of active tectonics: use of surficial Earth processes. In: Wallace, R.E. (Ed), Active tectonics, Studies in Gephysics. National Academy Press, Washington, DC, pp. 136-147.
Keller, E. A. &  Pinter, N., 2002- Active tectonics, Earthquakes, Uplift and Landscape. Prentice Hall: New Jerey.
Mayer, L., 1990- Introduction to Quantitative Geomorphology. Prentice Hall, Englewood, Cliffs, NJ.
Molin, P., Pazzaglia, F. J. & Dramis, F., 2004- Geomorphic expression of active tectonics in a rapidly-deforming forearc, sila massif, Calabria, southern Italy. American Journal of Science ,304, 559-589.
Pike, R. J. & Wilson, S. E., 1971- Elevation-relief ratio, hypsometric integral and geomorphic area-altitude analysis. Geological Society of America Bulletin ,82, 1079-1084.
Ramírez-Herrera, M. A., 1998- Geomorphic assessment of active tectonics in the Acambay Graben, Mexican volcanic belt. Earth Surface Processes and Landforms ,23, 317-332.
Rockwell, T. K., Keller, E. A. & Johnson, D. L., 1985- Tectonic geomorphology of alluvial fans and mountain fronts near Ventura, California. In: Morisawa, M. (Ed), Tectonic Geomorphology. Proceedings of the 15th Annual Geomorphology Symposium. Allen and Unwin Publishers, Boston, MA, pp. 183-207.
Salvany, J. M., 2004- Tilting neotectonics of the Guadiamar drainage basin, SW Spain. Earth Surface Processes and Landforms, 29, 145-160.
Silva, P. G., Goy, J. L., Zazo, C. & Bardajm, T., 2003- Fault generated mountain fronts in Southeast Spain: geomorphologic assessment of tectonic and earthquake activity. Geomorphology ,250, 203-226.
Strahler, A. N., 1952- Hypsometric (area-altitude) analysis of erosional topography. Geological Society of America Bulletin ,63, 1117-1142.