Morphotectonic of Kuhbanan Fault

Kuhbanan fault is located between Tabas and Yazd blocks in the southeast margin of Central Iran microplate, extending from the northwest of Kerman to the east of Bafgh, with 300 km length and NW-SE strike. The fault is one of the most seismic structural trends in the region. The latest seismic activity of the fault occurred on the seventh of October, 2003 with earthquakes of magnitude of 3.8 on Richter scale over the Kuhbanan segment of the fault. Kuhbanan earthquake fault consists of several segments. Movement in the southeast and central segments has been dextral strike-slip with a large reverse component and in the northwest segments dextral strike-slip with a large normal component during Plio-Quaternary.Morphotectonic effects of the active kuhbanan fault in mountain fronts of Kerman-Kuhbanan range and west Bahabad mountain range are landform features such as young and prominent fault scarps, linear mountain fronts, well  defined triangular facets, narrow V-shape valleys with steep longitudinal profiles, steep slopes of valleys and mountains, long drainage basins, deflected and offset streams, pressure ridges, shutter ridges, linear ridges, linear valleys, springs, sag ponds, young and small pull-apart basins along the fault. Therefore, with respect to the variety and numerous landform features, kuhbanan fault is introduced as a special model of morphotectonic landforms in Iran.Study of morphotectonic landforms and calculation of geomorphic indices such as, SmF, Facet%, VF V, SL, K and HY in the 32 fronts and 33 rivers with similar rock resistance along the fault segments, indicate that the degree of tectonic activity has been different in the fault segments during the Plio-Quaternary times. Therefore, the fault segments can be classified as very active, active, moderately active and with low tectonic activity.Based on the landforms and morphometric indices obtained along the Kuhbnan fault, the fault segments are classified as follows:1) The first class segments: Gisk Dartangel, NW-Dehzou, Khan-Makan Toghrolijard, Charmis segments that have the highest tectonic activity. 2) the second class segments: Khanok, Rigabad, Dahou, Katgouyh, Gazouyh, Apang-Sarbagh, Dezouyh, SE Gavar, Dargazri-Darhod, Pasando-Babkham, Fakhrabad, Bonestan, Khoshabad, Hossianabad I., II, Kuh-e-Sorkh I, II, III, Kuh-e-segoush, segments have been active. 3) The third class segments: West Katgo, Abbasabad, south-east part of Dargas=Godgas, Gavar and Kuhbanan segments have low activity. 4) The fourth class segments: Rushk, Dasht-e-Khan, Babrouyeh and Asadabad segments have the lowest tectonic activity.It should be noted that based on morphotectonic data the most active and active segments are coincided with earthquake fault segments. However, earthquakes have not occurred over some active segments. It seems that earthquakes might occur over these segments in the future, or active morphotectonic data might not match the seismic activity of fault segments. Nevertheless, it is obvious that an appraisal of seismic activity of faults, based on the geomorphic indices and landforms features, must be taken into account with care.