Journal of Engineering Geology

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(paper pages 227-240) The Famenin,Kaboudar-Ahang,Ghahavand plains are located in the north of Hamedan province.The sediment thickness of thier aquifers is about 70-100 meters .In recent years, some big and dangerous sinkholes have been developed in this area.By the result of excavations that done in these plains and investigation of the sourrounded outcropped area,it was found that the bed rock of this area has been made of Oligo-miocen limestones. According to the field observation,the measuring of joints and fractures systems, stud of thin sections, characteristics of excavations, yield of wells, the results obtained by chemical experiments of water and the estimation of parameters such as saturation and stability indexes,the amount of free carbon dioxide and the primary pressure of carbon dioxide gas,it was concluded that the Karstification phenomenon was happened in the bed rock and the Endokarst structures exist in it. Thus,The exist of Endokarst in bed rock cased to wells have been had high yield and Sinkhole were made in these area.In order to avoid or reducing the occurrence rate of Sinkholes in this area, we should avoid digging new wells in the bed rock and should stop the pumping of wells which have been drilled in the bed rock and have high yield.

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In this study, seepage phenomena through the left abutment of Marun dam are investigated. The Marun dam is a 170 m high rock fill dam, which regulates the waters of the Marun River, serves power generation, and flood control and provides irrigation needs. The dam site lies in the Zagros Mountains of southwest Iran. This region presents continuous series of mainly karstic limestone, marl, shale and gypsum ranging in age from Cretaceous to Pliocene. The region has subsequently been folded and faulted. All underground excavations are sited in the left abutment. The spacing of the diversion tunnels and pressure tunnel is considered to be acceptable, meaning relatively short, thus requiring 2 row grouting curtain into both embankments. Prior the reservoir impoundment, the concrete plug was constructed into the middle section of second diversion tunnel. Upstream section of tunnel was not concreted. During the first reservoir impounding, the old karst channels along ‘Vuggy Zone’ cut by the second diversion tunnel were reactivated and leakage occurred. The total amount of water leakage through the left bank of Marun dam was about. The unlined second diversion tunnel had a key role in connecting reservoir with karst conduit system. On the basis of detailed engineering geological analysis, the concept of remedial works was carried out. The main points of this concept are one of row grout curtain extension up to the section with shaly interbeds declared as watertight Asmari sequence (close to the watertight Pabdeh formation) and plugging of accessible section of main karst channel by concrete. In order to determine the seepage direction and karstification pattern, solubility studies were done. Also pinhole, XRD and XRF tests were carried out. The major joint system and interbedding cracks have predominant role in karst evolution process. Hydrogeological role of joints, perpendicu-lar to geological structure, is not negligible. As a result of these studies, seepage paths have been identified in the karstic limestone in the left abutment of the dam.

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The previous studies underteaken in the region indicate that the Ekhtiarabad and Chah-Darya sinkholes have occurred as a result of dissolution of underground gypsum rocks. Hence, they represent the likelyhood of hidden and threatening caves in the region. The presence of gypsiferous formations having surficial karstic features attest to this supposition. So, in order to determine the possible dissolving sites which may contain caves, the electrical conductivity and evaporite dissolution index maps of Kerman-Baghin aquifier were prepared and matched with groundwater recharge and mobility conditions. Accordingly, four suspected hidden- cave sites were recognized which include a large area around Ekhtiarabad village (as the most suspected site), one spot at the northwest of Baghin Plain and two other areas (south of Baghin and south and southwest or Kabutarkhan). Based on the utilized hydrogeochemical criteria, these last two areas may contain hidden caves, but, due to unsuitable hydrodynamic conditions, the possibility seems weak.

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One of the main methods of determining dispersive potential of clay is chemical tests. These tests are found on the basis of sodium ion as a main chemical element in dispersive clay. The examinations show that there is no correlations between results of physical tests and chemical criterions. In present research after preparing the results of tests on 18 borrow pit sources of clay materials of earth dams, we investigate the Dr. Rahimi's criterion with results of Pinhole Test and then bases on pinhole test results, we suggested the modified criterion of Dr. Rahimi's proposed general criterion. The results of investigations on the range of laboratory data shows that the correlations of Dr. Rahimi's proposed criterion with pinhole test is 63%, while this rate is 74% for our suggested modified criterion. Also it should be considered that Dr. Rahimi's criterion compiled according the results of 24 laboratory samples while suggested criterion in present research compiled according the results of 234 laboratory samples.

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One of the most important issues in the Reverse Analysis is analyzing the density resulting from the compaction of in fine soils. The conventional methods in d etermination of soil density are: sand cone, rubber balloon and nuclear density gauge. Trained neural network, as a suitable alternative for conventional methods based on models analyzed by those methods, is not only as accurate but it is also easier to calculate and implement. In the present article, a model based on multilayer perceptron of neural network is presented for prediction of the behavior of fine soils density in Sarabi Dam. The paper presents the implementation process and density of the soil layers. The input variables include 4 geotechnics and 4 implementation parameters. The geotechnic parameters consist of: optimum moisture content, maximum specific gravity, liquid and plasticity limit implementation parameters consist of: the number of cross rollers, thickness of the layers and density and moisture of the soil obtained from the site. The model is based on multilayer neural network, using the error back propagation approach and it is capable of calculating the density. As a result, the maximum specific gravity laboratory, using the aforementioned geotechnic and implementa-tion parameters, is presented. The method compates the maximum specific gravity laboratory accurately at almost 100 percent.

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Abstract
(Paper pages 1059-1076)
Physical and mechanical properties of intact rocks are very important in civil engineering works that interact with rock such as underground structures, dams,foundations on rock, and rock slopes. Therefore geomechanical parameters such as compression strength and deformation modulus of rock can have fundamental importance in the different stages of design. Determination of these parameters is time consuming and costly. Since Asmary formation has broad outcrop in the west and southwest of Iran and many large projects are located in this formation, therefore it is a requirement to accomplish the present research. This paper is dealing to analyzing data from laboratory of two major projects of the Khersan 1 and 2 dam sites. In this regard, the physical, mechanical, dynamic and durability properties of intact rock and geology controlling agents of these changes has been evaluated and analyzed. Finally, new experimental relations between different parameters have been presented.

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The Keshvari watershed is located at south east of Khorramabad city in Lorestan province. This area is one part of the folded Zagros zone based on structural geology classification. By consider the type of geological formations, topographic conditions and its area, this watershed is very unstable and capable for occurring landslide. In this study, artificial neural network (ANN) with structure of multi-layer percepteron and Back Propagation learning algorithm used for zonation of landslide risk. The results of ANN showed the final structure of 9-11-1 for zonation of landslide risk in Keshvari watershed. According this zonation, 23.81, 7.53, 6.49, 18.68 and 43.47 percent of area are located in very low, low, moderate, high and very high risk classes, respectively.

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One of the geotechnical hazards in the tunnels under high overburden and high in situ stresses is the phenomenon of rock burst. Rock burst is a typical geologic phenomenon caused by excavation in rock masses. In this phenomenon, because of stress released and explosion in rock masses, they are broken as large and small pieces and are distributed, so that leads to damage of peoples or equipments. Therefore, familiar with this phenomenon and its mechanism of occurrence, is need to analyze this issue. The second part of water supply Karaj-Tehran tunnel with a length of 14 km and about 4.5 m diameter is located in Tehran province. Rock burst analysis has been carried out in the tunnel from kilometer 6 to 9.5 that is critical section because of high overburden (up to 800 m) and presence of faults and crushed zones. In this paper, for predicting rock burst in the critical section of second part of Karaj-Tehran tunnel, four criteria including, Strain energy, Rock brittleness, Seismic energy and Tangential stress criterion are used. Analysis results show that units with high overburden have high possibility of rock burst. 

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Various types of numerical analyses such as   Finite Element Method, Boundary Element Method and Distinct Element Method, are used in rock mechanics and in engineering practices for designing rock structures such as tunnels, underground caverns, slopes, dam foundations and so on. In this paper, the results of back analysis of Koohin tunnel which is located in the first section of Qazvin-Rasht railway have been presented. The main purpose of this paper is to perform the back analysis of the mentioned tunnel with the use of numerical models. For modeling the tunnel, two different sections of 30+150 km and 30+900 km are analyzed with FLAC 2D software.  To perform back analysis the suitable interval of geomechanical parameters according to the tests which were performed on the core drillings has been determined. With the use of direct method in back analysis, the errors of models have been corrected in several steps and finally the geomechanical parameters in 30+150 km station (Elastic Modulus = 0.3 GPa, Cohesion = 0.21 MPa and Internal Angle of Friction = 34^°) and in 30+900 km station (Elastic Modulus = 0.3 GPa, Cohesion = 0.21 MPa and Internal Angle of Friction = 35°) have been achieved. The geomechanical parameters which obtained from back analysis are completely in the chosen interval and compliance with the results of tests which performed on core drillings. On the basis of  geomechanical parameters obtained from back analysis with the parameters which used in the design of the tunnel, the tunnel design and the structure method were confirmed.  

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One of the tests that is used for the characterization of soil abrasivity, is LCPC test. LCPC test device is designed for measuring the wear particles as small as pebbles (4-6.3 mm). In this study, some of the most important abrasive minerals were collected from different parts of Iran for analyzing the effect of the geological parameters on the ability of abrasive minerals. Firstly, amount of index minerals abrasivity is measured according to three standards of AFNOR P18-553, AFNOR P18-579 and AFNOR P18-560 that are the preparation of samples for testing, procedure of laboratory tests and analysis of grain size with laboratory sieves. The effect of geological parameters affecting the wear rate of the sample, including five parameters of shape, size, angularity and saturation rate of the environment, has been studied. The effectiveness of these parameters on the abrasivity of samples are studied according to NF ISO 5725 relating to usage of statistics, the accuracy of test method, the repeatability and the ability to reproduce a standard way of testing within laboratory (based on classification index X 06-041). Finally, after ensuring significant effect of these parameters on the abrasivity of minerals by help of SPSS, abrasivity rates for types of minerals that have the hardness below 7 in the Mohs hardness scale, have been predicted.

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Several studies show that during and before the earthquake, ground water existing in layers of the earth crust undergoes physical and chemical changes. These changes are recorded by measurement devices and known as "Geohydrological Precursors". Based on the studies conducted in this field, earth electromagnetic field waves experience fluctuations during and even before happening of the earthquake, which are called "magnetic anomalies". This type of anomaly is known as "geomagnetic precursor" within the scope of earthquake knowledge. S, the aim of this study is to assess the feasibility of making a connection between two groups of earthquake precursors (hydrological and geomagnetic precursors). In the present research, a series of tests has been done in order to investigate the effect of magnetic fields on physical and chemical properties of water, including Electrical Conductivity (EC), Total dissolved solids (TDS), Height of Water (HW). The tests were designed and conducted to be used in short-term and middle-term earthquake prediction. Analysis of the experimental results using statistical tests indicates that there is a partial meaningful relationship between magnetic fields (geomagnetic precursor) and physical and chemical properties of water (hydrological precursors), with the confidence coefficient equal to 95 percent

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Ground-Penetrating Radar (GPR) is a non-destructive and high-resolution geophysical method which uses high-frequency electromagnetic (EM) wave reflection off buried objects to detect them. In current research this method has been used to identify geometrical parameters of buried cylindrical targets such as tunnel structures. To achieve this aim, relationships between the geometrical parameters of cylindrical targets with the parameters of GPR hyperbolic response have been determined using two intelligent pattern recognition methods known as artificial neural network and template matching. To this goal GPR responses of synthetic cylindrical objects produced by 2D finite-difference method have been used as templates in the neural network and template matching algorithms. The structure of applied neural network has been designed based on extracting discriminant and unique features (eigenvalues and the norm of eigenvalues) from the GPR images and predicting all geometrical parameters of the targets, simultaneously. Also the template matching operation carried out using two diverse similarity approaches, spatial domain convolution and normalized cross correlation in 2D wave number domain. The results of the research show that both two employed intelligent methods can be applied for in situ, real-time, accurate and automatic interpretation of real GPR radargrams, however in general the neural network method has led to less error and better estimation than template matching to predict the geometrical parameters of the cylindrical tar

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Mountains are usually formation origin of their neighbor land surface features such as hillsides and plains. some problems and errors may occur in application of RS technique for generation of geology maps and in separation of these units from other similar units. The main objective of this study is to integrate RS and geomorphology approaches for identification of different geomorphology units and finally separation of debris lime stones from massive lime stones in Bahadoran region, Yazd province. For this purpose, a Landsat ETM⁺ image was acquired together with band ratios, principal component analysis and factor analysis approaches to generate lime stone distribution map. Results of this study show that (integration of RS and geomorphology sciences) can better generate the lime stone distribution map compared with the first one

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Ground settlement due to tunneling and the effects of the engineering geological factors on its dimensions and extensions, is a very important problem in shallow tunnel excavation projects in urban areas. Empirical method is one of the usual methods to study this subject. The empirical and dimension-less parameters of VL and k are the most important parameters in relation to this method that are estimated according to engineering geological factors. In this research, the values of these parameters were initially estimated based on preceding studies and the ground settlement was predicted using these estimated values of VL and k. In next stage, the results of predictions were compared with the real (measured) settlements happened due to Abuzar tunnel excavation. As the real settlements are less than the predicted ones, it was concluded that the real VL must be lower than the predicted values or the real k must be higher than the predicted values. With regard to the high dependency of these parameters to the soil cohesion, it seems natural cementation of Tehran alluvia has acted as a factor to increase the soil cohesion and has caused to decrease ground settlement due to excavation of Abuzar tunnel. For validation of this hypothesis, preceding findings about alluvia cementation were reviewed and the results of in-situ and laboratory shear and triaxial tests were compared with together. Then it is concluded that the higher cohesions of in-situ shear tests are occurred due to natural cementation of materials existing in Abuzar tunnel route

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This research focuses on the identification and description of various features of pseudokarst in different parts of Alvand granitic batholith, Hamedan, west of Iran. In the literature, karst features have been presented as specific types of terrain or landscapes with particular characteristics suites of well-known surface and subsurface dissolutional forms. Whereas, pseudokarst refers to non-dissolutional surface or subsurface features and landforms created in different areas such as slopes, coastal lines crushed stone areas, lava tubes and permafrost regions. In this research, a comprehensive field investigation program has been carried out. During the field investigations, the most important features of pseudokarst in Alvand granitic batholith have been recognized and classified. Results show a wide range of pseudokarst features in the Alvand granitic rock masses. These landforms are created by erosion, weathering processes and some holes caused by rock block movements along the rock slopes. Some of the most important forms and features of the pseudokarst in the studied area are consist of tafoni, genama, pseudokarren, talus caves, caves associated with the residual blocks and erosional forms along joints and fractures within the granitic rock masses

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In seismic prone areas, earthquakes happen more than just main shocks which are happen with sequences of shocks include of different intensity of aftershocks. In technical documents, these kinds of several earthquakes are called mainshock-aftershock ground motions. In this study, seismic behavior of RC frame under mainshock-aftershock with different ratios of maximum acceleration of aftershock to maximum acceleration of mainshock was evaluated. In this paper, nonlinear time-history analysis of frame were performed under mainshock-aftershock sequences and then the residual interstory drift ratio for comparing response of frame under seismic sequences was evaluated. The results show that, residual interstory drift ratio of frame, related to intensity of aftershocks to mainshock and enhance of intensity of aftershock due to increase residual interstory drift ratio of frame. Although, growth of residual interstory drift ratio of top stories more significant than below stories of frame.

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./files/site1/files/2Extended_Abstract.pdfExtended Abstract
(Paper pages 29-50)
Introduction
In some soils, special phenomena happen with increases in their moisture content that sometimes inflict major damages on development projects. Dispersive soils are one type of such soils. The physico-chemical properties of the particles in dispersive soils cause them to disperse and separate from each other upon contact with water. If dispersive clays are not accurately identified, they will cause damages and failures. In the Simin Dasht region of Semnan Province, some hydraulic structures have incurred serious damages because they are located on dispersive soils.
The present research studied the soils around the canal transferring water from the Simin Dasht to Garmsar. This 37-kilometer long canal is situated in Semnan Province between the Simin Dasht and the Garmsar diversion Dams. Scouring and soil erosion under the concrete lining of the canal has led to the destruction of the structure. After visiting the site and taking soil samples, double hydrometer and pinhole tests were performed. The effects of adding various amounts of cement, lime and aluminum nitrate on amending dispersive clays were studied and compared in the Simin Dasht region of Semnan Province.
Experiments
The effects of the quantities of cement, lime and aluminum amendment materials on stabilization of dispersive soils in the Simin Dasht region of Semnan Province were investigated. Two types of dispersive clayey soils were amended. Table 1 presents the characteristics of the soils. The effects of various amounts of lime, cement, and aluminum nitrate on reduction in the degree of dispersion in the tested soils were studied. The cement, lime, and soil samples were dried at 40˚C for 24 hours. It must be mentioned that the amount of added lime, cement, and aluminum nitrate were zero, 3, 5, and 7 percent.
Table1. Characteristics of dispersive soils used in this reserch

Gs	Optimum Moisture (%)	Plasticity Index, PI (%)	Plastic limit, PL (%)	Liquid limit, LL (%)	Natural water content (%)	Soil
2.72	15	2.54	15.09	17.63	13.84	A
2.66	11	6.33	16.11	22.44	3.02	B

Results
Average changes in discharge passing through the dispersive soil samples A and B, and through samples of these soils amended with lime, cement, and aluminum nitrate in pinhole tests are presented in Figures 1(a-f), respectively. Figure 1a indicates that the behavior of the A soil samples amended with lime did not follow any specific trend, but we can cautiously say that soil A will become non-dispersive when lime is added at 4.5 percent at all moisture contents. Increases in the quantities of the cement added to the dispersive soils A and B to stabilize them independent of the moisture content of the soils were also investigated (Figure 1c, d). Behavior of the A soil samples stabilized with aluminum nitrate followed a specific trend (Figure 1 e, f) contrary to those amended with the other stabilizers.
Conclusions
Results of the tests show that dispersion in soil A was amended (without completely preventing the occurrence of the scouring phenomenon) by the addition of cement or lime at 5 percent or aluminum nitrate at 3 percent. Moreover, dispersion in soil B was amended by the addition of cement at 3 percent, lime at 5 percent, or aluminum nitrate at 3 percent. Aluminum nitrate was a better and more effective amendment material for the dispersive soils compared to lime. Therefore, aluminum ions replaced the other ions in the structure of dispersive clays more suitably compared to calcium ions. Comparison of the results obtained from the pinhole tests performed on soil samples amended with aluminum nitrate, lime, and cement suggests that it took a shorter time for the samples to be stabilized with aluminum nitrate compared to the other two amendment materials.



Figure1 Variation of discharge due to soil stabilization, Lime (a and b), Cement (d and c), Aluminum nitrate (e and f)
 

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In recent decades many researchers have studied on the damage assessment of structures after a seismic event. To assess the damage of structures under an earthquake, it is so important to study the correlations between earthquake parameters and damages of the structures. A lot of seismic parameters have been defined by researchers to characterize an earthquake. Spectral parameters of an earthquake convey a variety of information about ground motion, so they can properly characterize an earthquake. Also a lot of damage indices were proposed by researchers to quantify the damage of the structures or to rank their vulnerability relative to each other. Park-Ang index is one of the best indices to describe the damage of a structure. In this paper, the correlations between spectral parameters of earthquakes and Park-Ang indices are studied. Three RC frames with different height are analyzed under far-fault earthquake records by nonlinear dynamic analyses. The correlations between spectral parameters and Park-Ang indices of the frames are calculated. The results show that in all the frames most of spectral parameters have strong correlations with damage intensity. In order to estimate the damage potential of an earthquake, some spectral parameters which have high correlations with damage intensity can be proper indices. Housner intensity, acceleration spectrum intensity and velocity spectrum intensity are shown to have strong correlations with damage intensity. In this paper, a new spectral parameter which has high correlation with damage intensity is achieved. 

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Introduction
Determination of the mechanical properties of rock materials has been remained as a challenge for engineering geologists. In-situ tests are rarely used to determine the mechanical properties of rocks due to difficulties in sample preparation, performing and interpretation of the results, high costs as well as the required long time for doing the experiments. The common approach to determine the mechanical properties of rock materials is through conducting laboratory experiments and estimation the in-situ properties based on these laboratory results. This approximation, which is called scale effect, has been remained as a challenge for engineering geologists and practical rock engineers for decades. ...../files/site1/files/0Extended_Abstract1.pdf

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 IExtended Abstract
 Introduction
The Iranian plateau is situated in the Alpine-Himalayan orogeny between the Eurasian plate in the north and the Arabian plate in the south. It is being shortened by the northward movement of the Arabian plate, which causes the most parts of Iran to be active and dynamic in terms of tectonic movements. The recent tectonic activity in the southern edge of central Alborz causes both development and deformation of the tectonically active landforms. Seismic records indicate a high frequency of earthquakes of relatively small magnitude (<4) and infrequent large earthquakes (>5.1) in the Alborz. The studied area is located in the southern central Alborz and at the edge of northwestern central Iran between seismic faults of Ipak (with approximately E-W trend) and Avaj (with NW-SE trend) that includes significant earthquakes. Generally, the dominant tectonic structures of the study area involve thrust faults. The Ipak fault is one of the major fault systems in the area, located about 120 km west of Tehran, and caused the 1962 Buin Zahra earthquake of Ms 7.2 (Mw 7.0). The earthquake was associated with 95 km surface rupture along the Ipak reverse fault with average throw of 140 cm and left-lateral displacement of 60 cm. This investigation has evaluated the active tectonics and the acceleration zoning of the region in order to analyze and measure the recent tectonic activities.
Material and methods
To assess the acceleration zoning of this region, seismic data, Kijko software, PSHA software and reduction equations were used; consequently, minimum and maximum acceleration for useful life of 75-year and 475-year building were estimated. In order to assess the relative tectonic activity through the study area, sub-basins and stream network were extracted by using Arc Hydro Tools software based on the DEM and in turn, 134 sub-basins have been resulted. The six geomorphologic indices were used as follow: Stream length–gradient index (SL), mountain front Sinuosity (Smf), Ratio of valley floor width to valley height (Vf), Asymmetric factor (Af), Hypsometric integral (Hi) and drainage Basin shape (Bs). Eventually, after calculating the relative tectonic activity index (Iat), the studied area was classified into four tectonic activity classes in ArcGIS10.1 as very high, high, medium and low.
Stream Length–Gradient Index (SL): The SL index indicates an equation between erosive processing as streams and rivers flow and active tectonics. The SL is defined by Eq. (1) 
SL= (∆H/∆Lr) Lsc                                        (1)
where ΔH is change in altitude, ΔLr is the length of a reach, and Lsc is the horizontal length from the watershed divide to midpoint of the reach. The SL index can be used to evaluate relative tectonic activity.  The quantities of the SL index were computed along the streams for all sub-basins.
Index of Mountain Front Sinuosity (Smf):  Index of mountain front sinuosity is defined by Equation (2). 
Smf = Lmf ⁄ Ls                                             (2)
where Lmf is the length of the mountain front along the foot of the mountain in which a change in slope from the mountain to the piedmont occurs; and Ls is the straight line length of the mountain front. Smf represents a balance between erosive processes tending to erode a mountain front, making it more sinuous through streams that cut laterally and into the front and active vertical tectonics that tends to produce straight mountain fronts, often coincidental with active faults or folds.
Ratio of Valley Floor Width to Valley Height (Vf): Vf is defined as the ratio of the width of the valley floor to its average height and is computed by Equation (3).
Vf = Vfw/ [(Ald-Asc) + (Ard-Asc) /2)]                            (3)
where Vfw is the width of the valley floor, and A_ld, A_rd, and A_sc are the altitudes of the left and right divides (looking downstream) and the stream channel, respectively. A significant relationship exists between the rate of mountain front activity and the Vf index. Consequently, the high Vf values conform to low uplift rates (Keller and Pinter 2002). The shape of a valley can also represent the Vf amount and uplift rate. Therefore, U-shaped valleys accommodate low Vf and high uplift.
Asymmetric Factor (Af): The asymmetric factor (Af) is a way to evaluate the existence of tectonic tilting at the scale of a drainage basin. The method may be applied over a relatively large area. Af is defined by Equation (4).
Af= 100(Ar/At)                                                   (4)
where Ar is the area of the basin to the right (facing downstream) of the trunk stream and At is the total area of the drainage basin. If the value of this factor is close to 50, the basin has a stable condition with little or tilting; while values above or below 50 may result from basin tilting, resulting from tectonic activity or other geological conditions such as lithological structure.
Hypsometric integral (Hi): The hypsometric integral is an index that describes the distribution of the elevation of a given area or a landscape. The Hi is independent of basin area. This index is defined as the area below the hypsometric curve and thus expresses the volume of a basin that has not been eroded. A simple equation that may be used to calculate the index is defined by Equation (5).
Hi = (average elevation - min. elev.) / (max. elev. - min. elev.)  (5)
Then Hi values were grouped into three classes with respect to the convexity or concavity of the hypsometric curve: Class 1 with convex hypsometric curves (Hi≥0.5); Class 3 with concave hypsometric curves (Hi<0.4); and Class 2 with concave–convex hypsometric curves (0.4≤Hi<0.5).
Index of Drainage Basin Shape (Bs): Horizontal projection of basin shape may be described by the elongation ratio, Bs, expressed by Eqation (6):
Bs = Bl/Bw                                        (6)
where Bl is the length of the basin measured from the headwaters to the mouth, and Bw is the width of the basin measured at its widest point. High values of Bs are associated with elongated basins, generally related to relatively higher tectonic activity. Low values of Bs indicate a more circular-shaped basin, generally associated with low tectonic activity.
Evaluation of Relative Tectonic Activity (Iat): The average of the six measured geomorphic indices (Iat) was used to evaluate the distribution of relative tectonic activity in the study area. The values of the index were divided into four classes to define the degree of active tectonics.
Results and discussions
Results of probabilistic seismic hazard analysis have shown that the minimum and the maximum acceleration for useful life of 75-year building is estimated as 0.33g and 0.45g and for 475-year one are 0.46g and 0.60g, respectively. These values are indicative of high risk in the studied area. Acquired values from geomorphologic indices and also acceleration zoning of the realm are indicative of high recent tectonic activities near Ipak, Hasanabad, Soltaniyeh and Avaj faults; they are extremely concordant with the obtained evidences and geomorphologic characteristics of the field samples. In this study, considering the diversity of the morphotectonic features, six morphometric indices relevant to the river channels, drainage basins, and mountain fronts were computed for every catchment, and consequently, a single index (Iat) was calculated from the these indices for each of 134 subbasins to define the degree of active tectonics. Finally, the Index of the Active Tectonic (Iat) was calculated through which the study area is classified into four tectonic activity classes, from very high to low; 1—very high (1.0≤Iat<1.5); 2—high (1.5≤Iat<2.0); 3—moderate (2.0≤Iat<2.5); and 4—low (2.5≤Iat). The distribution of the four classes of Iat has been presented in a well classified map. The indices have represented a quantitative approach to differential geomorphic analysis related to erosion and depositional processes which include the river channel and valley morphology as well as tectonically derived features, such as fault scarps. We also evaluated the outputs of the morphometric analyses based on field-based geomorphological observations. Thus, these results are proved to be extremely beneficial to evaluate relative rates of active tectonics of this region.
The values of Af show widespread drainage basin asymmetry related to tectonic tilting, particularly associated with Ipak fault. The values of Smf suggest that mountain fronts are tectonically active, and the values of Vf show that some valleys are narrow and deep, suggesting a high rate of incision. The parts with class 1 and 2 of the relative tectonic activity are located along the main faults of the region, such as Soltaniyeh, Avaj, Hasanabad and Ipak faults and show high correlation with observed landforms during the field investigations such as the direct mountain fronts, fault gorges, fault scarps, and deep v-shaped valleys. Besides, the high amount of the relative active tectonic index shows a good consistency with the recent tectonic activity, namely tilting and deformation of the Quaternary units, which is the indicative of the effect of compressive stresses, affecting the region.
Conclusion
In this study, according to the current tectonic activity using the Iat index, it was found that the study region represents a high current tectonic activity along the fault zones. The values of SL, Hi, and Bs were found to be high along Soltaniyeh, Avaj, Hasanabad and Ipak faults segments.
According to the earthquakes and probabilistic seismic hazard analysis in the study area, it can be said is worthy to note that some basins which are located among active faults, are seismically dangerous.  However, they show low relative active tectonic index (Iat)../files/site1/files/121/AleeiAbstract(1).pdf