We performed a 3D teleseismic tomography to image the lithosphere and upper mantle structures in the northwest of the Zagros collision zone and the Iranian plateau. The Iranian Plateau is a high relief region that has formed as a result of continental collision between the Arabian plate and Eurasia in the latter part of the Cenozoic. The Zagros and Alborz active tectonic belts are situated on the southwestern and northern margins of the Plateau, respectively. Our aim was to investigate the lithospheric structure and the geometry of the subducted oceanic slab in a region encompassing the Zagros and Alborz mountain ranges in NW Iran. For this purpose teleseismic data recorded at two temporary networks in NW Iran and several stations of the Iranian permanent networks were used in the ACH tomography scheme developed by Aki et al. (1977). A total number of 8164 seismic rays where used in the tomography. Checkerboard synthetic tests were performed to insure that the tomography had adequate resolution power in order to have reliable interpretation of the results. Our seismic tomograms distinguish three major anomalous regions in terms of velocity variation with adequate resolution in the study area. They are: 1) a high velocity anomaly corresponding to the Zagros lithosphere, 2) two low velocity anomalies underneath the Sahand and Sabalan volcanos in NW Iran, 3) and a deep high velocity perturbation delineating position and geometry of the subducted oceanic slab in the upper mantle. Our results show the lithosphere beneath the Zagros Mountains has a thickness almost twice as that in central Iran and the Alborz Mountains. NW Iran shows no high velocity character at shallow depths, indicating a thin and possibly warm lithosphere. In NW Iran the lithosphere reaches its minimum thickness anywhere throughout the Iranian Plateau. Two low velocities in our model indicate anomalously warm crust beneath the Sahand and Sabalan volcanos. These crustal anomalies link with deeper low velocity regions in the lithosphere and shallow upper mantle. The presence of low velocities at this depth range in NW Iran can either be related to partial melting associated with the mantle wedge region above the subducted slab, or to the possibility of lithospheric delamination. We have traced the Tethyan slab down to 650 km depth in the central part of the model. A discontinuity in the structure of the subducted slab has been mapped in the depth range of 250 km at the base of the Zagros lithosphere, which can be the location of a slab detachment in the central part of the model. The location and depth of the velocity discontinuity point to a post-collisional and relatively young slab breakoff of 10-5 Ma age in NW Zagros

The amplitude of seismic waves is generally reduced while passing through the earth under the influence of the two main factors of geometrical spreading and apparent attenuation of seismic waves. Scattering attenuation, as an elastic phenomenon, redistributes seismic wave energy due to the collision of seismic waves (P, S and surface waves) with randomly distributed heterogeneities. The attenuation of coda wave, backscattered waves form heterogeneities, is one of the most important parameters in the estimation of seismic wave attenuation. In this study, the attenuation of seismic coda waves as scattered body waves has been estimated using single back-scattering model.

The most common method to estimate attenuation is single back-scattering model. Here, we use short-time Fourier transform (STFT) instead of bandpass filter. For each individual frequency, the envelopes of STFT coefficients of extracted waveforms for lapse times of 30, 40, 50, 60, 70, 80 and 90 seconds are measured as the BPF method. The obtained envelopes have been used in order to estimate attenuation at each individual frequency. Since the length of the window is constant in the STFT method, it is possible to determine fairly accurate frequency in a short window. However, to this purpose, each waveform is divided into 1 s windows (50 samples) overlapped by 90% (45 samples), and the STFT has been calculated for each window.

In this study, attenuation parameter has been estimated in northwestern Iranian plateau using the STFT method. The results show good correlation between seismicity and tectonic of the study area for lapse times greater than twice the S- wave travel time, especially for lapse time of 40 s. At lapse time of 40 s, the frequency-dependent relationship has been estimated as Q = (103±1)f(0.88±0.04) using the STFT method. It is concluded that the STFT model can be used as an appropriate time-frequency tool to study the energy attenuation of high-frequency coda waves due to the high correlation coefficients and low standard deviations of the relationship. Furthermore, the relatively low values of quality factor in frequency attenuation relation show that there is high heterogeneity among shallow layers of Iran northwestern region that is possibly due to the relatively high seismicity of the region.

Due to the topography and geological situation, East Azarbaijan province has massive deposits of ornamental and construction stones. As the province is located on "the hot spring marble and travertine belt of Iran" due to past activity of Sahand and Sabalan volcanoes, ornamental stones of this region are famous worldwide and have desirable quality. In this article, geological conditions and formation of travertine deposits of Iran has been studied, followed by an investigation on the physical and chemical specifications of ornamental travertine of Azarshahr. In addition, results of laboratory studies and chemical analyses are presented and discussed in different tables.

Iran Plateau is part of the Alpine-Himalayan orogenic system in western Asia. It is located in a seismically active region affected by a transpressional tectonic regime of oblique convergence, generated by the convergence of the Arabian plate toward Eurasia. The current morphology of Iranian plateau had been dominated by opening and closing of the Paleo-Tethys and Neo-Tethys oceans in the past. Current lithospheric deformation in the NW Iran is shaped by the convergence of Arabia and Eurasia and the westward motion of the rigid South Caspian Basin. The South Caspian Basin is a relatively aseismic rigid basement block and has affected the deformation history of its surrounding continental regions. The South Caspian Basin and the Kura depression to its west are thought to be a relic back-arc of the Tethyan Mesozoic subduction caught up in a continental collision zone similar to the Black Sea and the eastern Mediterranean. The South Caspian Basin is a piece of unusually-thick oceanic-like crust, because of its low elevation and its west and southward motion relative to central Iran. Here we present results of a S-receiver function analysis for a 290 km long temporary seismic network in the NW Iran. The network is a linear array stretching from the western coast of the South Caspian Basin to the Lake Urumieh. We computed the individual S receiver functions for 23 broad-band seismic stations and then we stacked them based on their piercing points at depth of 80 km. To calculate S receiver functions, the teleseismic S waveforms were cut from 200 s before to 100 s after the theoretical S wave onset. ZNE-component waveforms were rotated into the ZRT coordinate system and the R component was deconvolved from the Z component. To make S receiver functions similar to P receiver functions, we reversed the time axis and the polarity of S receiver function time series. The Gaussian smoothing factor was selected equal to 1.0 for both data sets, which is equivalent to the application of a Gaussian low pass filter with a corner frequency of ~0.2 Hz to the receiver functions. Piercing points at north and south of the linear profile were separated into two different data sets to avoid the stacking of 3D heterogeneities. Stacking receiver functions confirms a thin crust east of the Talesh Mountains juxtaposing with a thick continental crust beneath the NW Iran. We interpret the thin crust as an oceanic-like crust belonging to the South Caspian Basin. The detected Lithosphere-Asthenosphere boundary is almost shallow with an average depth of ~100 km. However, its variations across the profiles are different in each data set. Variations beneath the region south of the profile are minor revealing a flat, thin lithosphere beneath the region. The lithosphere (as well as crust), however, becomes thick beneath Sabalan volcano, north of the profile, probably due to convergence of the NW Iran and the South Caspian basin above the North Tabriz Fault. This interpretation implies that the North Tabriz Fault is a continental suture between the NW Iran and Central Iran plateau.

In the present work, the ignimbrites of Sabalan and Sahand volcanoes have been studied. The geological, petrographic, and geochemical properties of Sabalan and Sahand ignimbrites presented here. Sabalan ignimbrites contain plagioclase, amphibole, pyroxene, biotite phenocrysts and rock fragments. The rock fragments are mostly pumice and obsidian. Sahand ignimbrites have plagioclase, sanidine, quartz, hornblende and biotite glassy groundmass. Sieve texture in plagioclase crystals and corrosion of the margin of some minerals in Sabalan and Sahand ignimbrites indicate that primary magma is affected by contamination and mixing before eruption. The Sabalan and Sahand ignimbrites have composition range of trachy- dacite to rhyolite and dacite to rhyolite, respectively. In the trace elements normalized diagrams, these rocks are enriched in LREE and LILE relative to HREE and HFSE, respectively. High content of Sr/Y-Y and La/Yb-Yb indicate that these rocks have high SiO2 adakites nature. The Sabalan and Sahand ignimbrites were sourced from the partial melting of lower crust with garnet amphibolite composition. The degree of partial melting in the primary magma of sabalan ignimbrites appear to be higher than that of Sahand ignimbrites.

The potential field data like Gravity data, Magnetic data, Self-potential data, and other natural source data are accessible but hard to interpret and model. Numerous research presents ideas for modeling the potential data; however, they are mostly based on inverse or forward modeling needing a priori constraints and information. In complicated geology and tectonic setting, we do not have convenient access to a priori information to define the constraints. So, we must develop a pure geophysical interpretation method without geological constraints and minimum complexity. In this research, the Normalized Full Gradient’s ability to find the gravity anomaly model was studied. The Normalized Full Gradient method is an effective method for determining anomalous bodies, such as the distribution of oil and gas fields or structural boundaries. The Normalized Full Gradient method depends on the downward analytical continuation of normalized full gradient values of gravity data. Analytical continuation discriminates certain structural anomalies which cannot be distinguished in the observed gravity field. The Normalized Full Gradient of the gravity anomaly is often used rather than the gravity anomaly itself for detecting underground spaces because it is stable and indicates the locations of source bodies. The weakness of the Normalized Full Gradient is the 3D modeling limitation, as we can only calculate the 2D response in practice. On the other hand, the responses can not describe the negative and positive parts of the anomaly. But a unique advantage of the Normalized Full Gradient is, that it does not need the primary information for gravity data modeling. In this research, we used the Normalized Full Gradient for the large-scale Bouguer gravity anomaly interpretation. Bouguer gravity anomaly wavelengths contain information about density distributions of upper mantle and lithosphere structures. A gravity profile is most often a combination of relatively sharp anomalies that must be of shallow origin and very deep and large anomalies with a regional nature.The study profile has a 400 (km) length from SW to NE of North Western Iran, and Sahand, North Tabriz Fault, and Sabalan are the most important structures in the study area. The Normalized Full Gradient synthetic model data study provides the opportunity for the real data recovered model judgment. So, we first showed the Normalized Full Gradient recovered model of the synthetic data test and then based on the resolution of the Normalized Full Gradient used, it provides the lithospheric density of North Western Iran. The result shows the low-density mantle wedge which is probably is beneath the North Tabriz Fault that is responsible for the formation of distinct lithosphere conditions. So, the wedge can explain the complicated tectonic setting of North Western Iran. The mantle wedge has more than 50 (km) wide and more than 40 (km) depth. seemingly, this mantle wedge directly affects the North Tabriz Fault, Sahand, and Sabalan in the shallower depth. The sharpest effect is for the North Tabriz Fault in the shallower part of the mantle wedge and following the shape of the wedge, we can see a sharper effect on the Sabalan in comparison with Sahand.

Evaluation of interaction between new and existing underground spaces is one of the important problems in tunneling in urban areas. In some cases it is necessary to excavate tunnels close to each other’s. This، in turn، will lead to important interaction between these tunnels. In this paper، using 3D numerical modeling of line 1 twin tunnels of Tabriz urban railway، excavation stability of these tunnels، using critical strain of Sakurai، have been studied. Also displacement pattern of lining in both twin tunnels (Sahand & Sabalan) have been investigated. In next step، effect of excavation of these tunnels on the subsidence of surface and adjacent buildings، using Cramer criteria and finite difference method (FLAC 3D)، have been studied. For the purpose of study of the interaction effects between these tunnels، forces and moments that act on the segmental lining of each tunnel and their safety factor have been verified. Eventually، stability of pillar that lies between two tunnels، have also been evaluated. The results show that: 1-twin tunnels of Tabriz metro will be stable during excavation. 2-Surface subsidence due to excavation of these tunnels will have no important effect on existing structures. 3-Safety factors varies between 5-10 on the different positions of segmental lining. 4- Pillar that lies between twin tunnels will be stable

Climate is a complex system which is changing mainly due to the increase in greenhouse gases. Climate change is slowly expanding across the globe and its impact can be seen on water, agriculture resources and climate parameters in regional scale (Babaian et al., 2009: 136). Climate change is one of the characteristics of the natural cycle of the atmosphere, which is caused by abnormalities and/ or fluctuations in the process of meteorological parameters such as rainfall and temperature. Temperature as important climate variable, causes the most common environmental changes. The effects of temperature changes in the lives of people and other living beings have caused human to face another concern in the real world, which caused a lot of research in this connection in a way that the studies suggest the uniform unchanging temperature in all parts of the world, i.e. the intensity and timing of temperature increase is not the same everywhere (Thuraya et al., 2007). In the world and Iran climatology, numerous studies have been made in the field of climate and its changes in several areas. For example, Lettenmaier et al. (1994, 586-607) in the United States of America, Domonkos and Tar (2003, 131-147) in Hungary, Seleshi and Zanke (2004, 973-983) in Ethiopia, Kumar et al. (2005 , 123-150) in Italy, Qiang et al. (2005, 217-222,) in Egypt, Feriwan Kadioglu (2008, 69-89) in Jordan, Tayanc et al. (2009, 483-502) in Turkey, Mohammadi and Taghavi (2005. 72-115), Azizi and Rowshani (2008, 13-28) in Iran have proven some trends in time series of temperature. In this study, by the using of geo-statistic methods, inter-decadal changes in Iran were reviewed and analyzed.
To study the inter-decadal changes of temperature, data resulted from interpolation of daily temperature observations from 663 stations were used in Iran since the beginning of 1961 to December 2004. The data is taken from the Asfezari database. Data spatial resolution of the data is 15 × 15 km, which is written in the picture system of similar conical Lambert. The number of cells across the country is 7187. To enhance the temporal resolution of the data base, daily observations of temperature from 2004 to the end of 2011, using the same method and the same spatial resolution, were interpolated and added to the data base. To analyze the data and to draw maps, programming features of MATLAB software and the GIS software were used, respectively. In order to obtain more detailed information about the temperature of Iran, anomalies and the average (weight average) were studied and analyzed. In the process, the temperature deviations for any climatic normal period happened, using map algebra method. The average of every year in different periods was compared to the average annual values of the same period, and by subtraction of them, related anomalies were calculated. Average distribution is in fact the center of the spatial distribution, which is defined as follows:... .
In order to determine the spatial distribution of pattern as a map, Moran cluster analysis and outlier, which is known as the Anserine Local Moran I, have been used.
Local Moran's I statistic is calculated as follows (Alijani et al. 2013: 8):
Discussion of Results and Spatial autocorrelation is one of the most useful and important analys tools for research on spatial data. This analysis not only provides in itself useful information about the interrelated effects, but also the results are used for many more complex statistical analyses.
The results of the spatial distribution of temperature anomalies are shown in this study, in which although the studied in each 5 periods faced concrete changes, the changes are a function of latitude and altitude. Therefore, the center of gravity orientation of temperature in every five periods, which tends to the southeast of the country, confirms the above claim. The results of the analysis of the local Moran’s I suggests that all five studied periods of coastal shores of the Persian Gulf and Oman Sea up to a distance of approximately 200 kilometers from the coast are a high cluster model. While some parts of the northeast of the country, northwest of the country (especially Sahand and Sabalan) and along the Zagros Mountains had a low cluster model, or in other words, had negative spatial autocorrelation. The appearance of cluster with positive correlation in the South Coast, in addition to the impact of the latitude and the exposure of the subtropical high-pressure in this area shows the uniformity of the temperature in this region. As in a cluster a share characteristics of the pixels is required, and due to the heterogeneity of the central regions of the country in terms of altitude, despite the desert areas and high temperatures, these areas are not considered as a part of the cluster with high temperatures. This may be due to temperature differences in desert areas adjacent to moderate temperatures in the high mountains, and cool temperatures. In other words, the existence of maximum temperature in a region in Loot Desert adjacent to areas with relatively cool temperatures at high altitudes cannot lead to the creation of a cluster. The advancement and retreatment of synoptic systems in the general circulation of the atmosphere cause colder or warmer years’ experience in the country, in a way that the advancement of polar vortex to the north of the country causes cold air in the region, and the sustainability of the system in the country greatly affect the country's average temperature. Thereby, the retreatment of the vortex provides conditions for entrance of the subtropical pressure in the country. The more the system takes the country's total area, the more average high temperature would be recorded for the country. Finally, the temperature differences in the average temperature of any year are visible in the related expansion zone of each cluster.

The explanation of the elastic, or velocity structure of the Earth has long been a goal of the world’s seismologists. For the first few decades of seismological research, the investigation on velocity structure was restricted to the determination of one-dimensional models of the solid Earth and of various regions within it. Seismologists are currently obtaining three dimensional velocity models and are working to resolve finer and finer features in the Earth. The knowledge of seismic velocity structure of the crust and the upper mantle is important for several reasons: these include accurate location of earthquakes, determination of the composition and origin of the outer layers of the Earth, improvement of our ability to discriminate nuclear explosions from earthquake, interpretation of large-scale tectonics and reliable assessment of earthquake hazard. The Iranian part of the Alpine-Himalayan collision zone consists of an assemblage of lithospheric blocks, features a complex tectonic setting, which results from the collision and convergence of the Arabian plate towards Eurasia, thus investigation of the structure of the lithosphere and the asthenosphere of the Iranian plateau is of great interest.
The North West of Iran is affected by important seismic activity concentrated along the North Tabriz Fault. In recent centuries, more than five successive and destructive seismic events have occurred along the North Tabriz Fault. The North West of Iran is particularly rich in geological and Most of NW Iran is located in a volcanic arc zone of Cenozoic age, including the Quaternary. Some of the main geological features in the North western of Iranian plateau include the Sahand Volcano, the Urmia Lake, salt deposits, travertine deposits, springs, limestone caves, tectonic structures and Cenozoic vertebrate fossils. Sahand and Sabalan peaks are the most prominent geological as well as topographic feature in the region.
The aim of this study is to obtain two dimensional tomographic maps of Rayleigh wave group velocity of the Northwest part of Iran plateau. To do this, the local earthquakes data during the period 2006 to 2013, recorded at 10 broadband stations of the International Institute of Earthquake Engineering and Seismology (IIEES) were used. firstly, Rayleigh wave fundamental mode dispersion curves using single-station method were estimated. In single-station method after the preliminary correction, Rayleigh wave group velocity for each source-station using time-frequency analysis (FTAN) were estimated. After estimating group velocity dispersion curves, using a 2D-linear inversion procedure, the group velocity tomographic maps for the period 2-50 s were obtained. Each tomographic map has been discretized with a grid of 0.5° of latitude per 0.5° of longitude. The results at period 5 s show a low velocity anomaly beneath the Sabalan volcano, whereas beneath the Sahand volcano a high velocity anomaly is observed. At period 10 s the results are different. Beneath the Sabalan volcano a high velocity anomaly is observed, whereas beneath the Sahand volcano and also along the Urumieh-Dokhtar Magmatic Arc a low velocity anomaly are observed. At period 20 s in most of the study area, a low velocity anomaly is observed. The results at period 40 s are different, so that a low velocity anomaly in the southern part and a high velocity anomaly in the northern part are observed.

Multi-Criteria Decision Making methods have progressed extensively in the past decades and have been applied in various disciplines. Application of them in different fields of geology, especially in assessment of geological hazards which are usually multi-criteria in character, can be very helpful. Studies such as the present study will widen their uses in various fields of geology. Volcanic eruptions in the past centuries attest that stratovolcanoes are more hazardous than other volcanoes and their activity may be disastrous. Hence, in this study, multi-criteria decision making methods of EN-SAW and ANP have been applied to assess and rank the reactivation hazard of Iranian stratovolcanoes (Damavand, Taftan, Bazman, Sahand, Sabalan, Bidkhan and Mesahim) as a case study. So, firstly, the criteria useful in their hazard assessment were selected which include the age of the latest eruption, the presence or absence of tectonic regime creating the volcano, the status of post volcanic activities (e.g. hot springs) and the extent of erosion. Afterwards, they were scored by several experts and lastly, by applying EN-SAW and ANP methods and using Super Decision software, the reactivation hazard scores of these volcanoes were determined and they were ranked. In both these methods, the Damavand volcano ranked first. So, its reactivation potential is higher than other ones and must given the first priority, its threats must be evaluated, its hazard zoning maps should be prepared and (as a kind of monitoring) a seismic station can be established. According to the applied methods, Bazman, Taftan and Sablan volcanoes acquired nearly the same scores. So, ranking after Damavand and it is recommended that they be considered as semi-active (dormant) volcanoes. The condition for Sahand volcano is not clear. However, Bidkhan (in Bardsir town of Kerman) and Masahim (North of Shahrebabak town) both acquired very low scores. So, they are considered as inactive and are not hazardous.