Construction in near fault regions is of specific importance for which safety should be considered against seismic faults. Fault rupture zone is a region that civil construction receives highest damage from near fault zone effects such as surface fractures, strong ground motion, displacement and landslide in the regions of great slope and rough topography. In this study, first, the three dimensional topography and slope map of the studied area are prepared. The fault rupture zone of North Tehran Fault is calculated after developing the faults density and magnitudes gained from three probable mobile scenarios. Present study suggests a fault rupture zone of 2.2 to 1 km for North Tehran Fault.

Fault migration, an important phenomenon in fault-zones, is neither fully investigated nor defined comprehensively. In this paper, based on observations on Ardekul active fault zone (Eastern Iran), an evolutionary path is considered for strike-slip fault zone. According to this evolutionary path four stages; namely embryonic, youth, maturity and declining have been recognized. This evolutionary path may be generalized over different scales of brittle deformation. The proposed evolutionary path makes the fault migration clear. A case study of Ardekul fault zone is chosen for applying defined fault zone evolution and fault migration. Based on the results, fault migration can be divided into two grades; first, the prior and second, the posterior fault migration. Details of prior migration are distinguished including time of occurrence, stages, types, scales and mechanisms of migration, effective factors on migration and its characteristic features. The posterior migration can be studied from the viewpoint of prior migration. Moreover, the fault migration can be comprehensively classified into two topics; production-oriented fault migration and development-oriented fault migration. Some clay cake experiments are also designed to show the prior and posterior fault migrations.

Active deformation in Alborz range is due to N-S convergence between Arabia and Eurasia. This paper provides geomorphic traces of regional deformation in NW Iran in order to characterize active faulting on major faults. Soltanieh and North Zanjan fault systems are involved in convergence boundary extent between South Caspian Basin and Central Iran. Soltanieh and North Zanjan faults are major reverse faults in the study area. Soltanieh fault has been probably responsible for historical Soltanieh earthquake in 1803. Accurate mapping accompanied by field observations enabled offset determination along active faults. We presented geomorphic documents indicating left-lateral strike-slip movements in Soltanieh fault zone. Kinematics is achieved through analyzing inversion results obtained from kinematic measurement sites which are generally scattered along Soltanieh fault zone. Fault kinematic data inversion results (slip-vector measurement in fault planes) indicate a dominant NE trending horizontal maximum stress axis (σ 1). Kinematic inversion results infer reverse faulting mechanism accompanied by strike-slip component.

In This study, the microtremore data were used for recognition and mapping the South Mashhad fault zone. For this, in 27 points and 5 profiles normal to the mountain of south Mashhad single stations microtremore data were measured and by the dominant frequency are estimated using the spectral ratio (HVSR) method. Then Map of the period and its variations drawn In the highlands south of the city and the Stations with sudden change in the amount of frequency are marked on the map. Moreover, anisotropy of dominant frequency and amplification in all stations are checked and the station with high anisotropies of amplification marked. Finally, by comparing the results of both methods with reviews the area borehole and evidence of fault activity on aerial photographs, location of Mashhad fault zone are proposed. The results have good agreements with site evidence and aerial photo interpretation.

Fault traces within the Qozlu fault tip zone, located at the southeast end of a segment of the North Tabriz fault, which reaches to the Bozqush deformation zone, represents the formation of a horsetail structure. There is, however, no information about the type of this structure or its deformation pattern. In this regard, study of topography (analysis of the relative elevation difference at two scales—within the overall deformation zone and in buffer zones along streams flowing within the zone), surface slope, asymmetry factor, and geological information indicate that: 1) the fault tip zone is a contractional horsetail splay; 2) a compressional tectonic regime is dominant within the fault tip zone and the trend of maximum compression is N20W-S20E; 3) two different fault zones with maximum and minimum tectonic activities are recognised along two streams within the fault tip zone ; 4) the overall dip-slip component within the stream-related fault zones is reverse or thrust. These results provide significant information about tectonics of the Qozlu fault tip zone and improve our knowledge of deformation within the North Tabriz fault zone. This study, also, demonstrates the importance of using stream longitudinal swath profiles to obtain tectonic information directly from topography.

The Sangbast-Shandiz fault zone, with a length of about 57 km, a width of moderately 2 km, and a NW-SE direction, is located about 15 km in the west of Mashhad city. That is one of the major faults in the Binalud Mountains. Geomorphic evidences illustrate that the Sangbast-Shandiz fault zone has dextral strike- slip offsets with thrust activity. In this article, we investigated geomorphic features of faulting, by using remote sensing analysis of satellite images, digital elevation maps, and field work studies. These geomorphic attributes consist of a topographical distortion along the fault line on the surface and offsets or cutting in liner features as drainage systems like stream channels and liner eroding crests. In the results, we found out that increasing of fault slip quantity, increased elongation, widened the fault segments, and so joined pre-existing faults and segments and decreased fault steps. In addition, the southeast mid of Sangbast-Shandiz fault zone is releasing energy and seems to be in a growing state while the northwest mid is in a compressing stress state.

The Qom- Zefreh fault zone is located in the Central Iran. This fault considered as one of the fundamental faults of the Central Iran which is active in quaternary. Travertine deposits has been affected by the Qom- Zefreh fault zone. The Qom- Zefreh fault zone has been known as a quaternary fault in the western part of central Iranian plate and it’s recently of movement is considered early. The values of geomorphic indices as well as Iat often change corresponding to the distribution of this fault zone. Therefore, estimation of the morphometric parameters to identify the effect of its recent activity on the tectonic evolution of the drainage basins of the study area is essential. In order to assess the relative tectonic activity through the Qom- Zefreh fault zone, sub basins and stream network were extracted by using Arc Hydro Tools software (an extension of Arc GIS software, ESRI) based on the DEM and in turn, 103 sub basins have been resulted. In this study, considering the diversity of the morphotectonic features, six morphometric indices relevant to the river channel, drainage basin, and mountain fronts were computed for every catchment, and consequently, a single index (Iat) was calculated from these indices for each of 103 subbasins to define the degree of active tectonics…

The south of Tehran lies in vicinity of the active faults such as Pishva, Kahrizak and Eyvan-E Key and in the case of re-rupturing of these faults a serious disaster, perhaps financial and life losses may be occurred. In IBC (International Building Code) formula (Darlene & Batatian, 2002) dip, displacement and footing of building and criticality of building code have been considered as important factors for setback zone. In up thrown side we must: S=U (2D+F.tan-1q) In down thrown side we must: S=U (2D). There is gap of world standard setback zone in Pishva. The Iranian setback zone code does not respect the IBC formula and is based on the field observations. the formula of IBC consider slip rate of the fault, the displacement factor, the type of structure, foundation of the building and the sensitivity of structure, while in Iran the zoning of the Berberian et al. (1364), which is based on the fault type and field observations has been continuously used. Thus, with combination of these two methods and with regard to the geotechnical issues, construction can be designed more carefully.

In this paper, the structural evolution of Bamu fault zone located in the Zagros folded belt zone is presented as an example of northeast-trending fault zone in the Zagros, using the kinematic and dynamic analysis of accompanied structures. Based on structural and paleostress analyzes two phases of shortening were determined as NE and NNE. In order to define the chronology of the deformation stages in the region, the relationship between fault structures and folds in the folded rock formations has been utilized. The result showed that the first compression stress trend in the area was NE that caused formation of the Bamu transverse Fault with left-lateral strike-slip mechanism and its accompanied structures. Since this stage of deformation has affected the Oligocene-early Miocene formations, more likely occurred at this time. During the next phase the shortening direction, due to change in the collision zone direction of the Arabian-central Iran in the Miocene-Pliocene, has changed to NNE which causes development of younger structures in the form of folding and reverse faulting in the fault zone. This shows that the NE-trending fault zones, like other major NW-faults, in Zagros affected by the change in the convergence of Zagros collision.