مجله پژوهش های دانش زمین
پیاپی 53 (بهار 1402)

The city of Ardabil is surrounded by faults, including the large seismic fault of Astara, which throughout seismic history of the region, several earthquakes have occurred along that. The focal depth of most earthquakes is low and close to the surface (5 to 30 km) at Ardabil. In this research, 7 linear sources and 23 regional sources have been identified. After aggregating historical and instrumental earthquake information, the reliability and completeness of the catalog should be evaluated. Due to the lack of reports of small earthquakes in historical data and the new periods of instrumental data, there is always an incomplete seismic catalog for a region. Because the existing catalog covers a long period of time, it contains temporal and spatial heterogeneities. The Stepp method is used to calculate the completeness of the catalog. Most earthquakes in this region have a depth of less than 40 and according to the cumulative distribution diagram, also most earthquakes have a focal depth of less than 20 km.

To carry out this research, the recorded earthquake data of the region taken from 4 sites IIEES, ISC, NEIC and University Geophysics Tehran, and Matlab, Zmap, Kijko and Ez-frisk software were used. Seismic device data used in the region includes details related to the earthquake spring, such as: date, time, latitude and longitude, magnitude and related seismic information, which are used to determine the seismic source of the faults. Data analysis for earthquake risk has been done using Ez-frsik software. In this study, the earthquake catalog for northwestern Iran has been examined in three-time series:A: historical earthquakes (period before 1900 AD); B: Systematic earthquakes of the first period (1900 to 1963) and C: Systematic earthquakes of the second period (1963 to 2020).

Kijko and Sellevoll method was used to determine the seismicity parameters of Ardabil region. This method has useful capabilities in using the list of heterogeneous earthquakes which is consistent with the characteristics of seismic data of Iran. The functions used in the Kijko program include the distribution of final values for earthquakes before the 20th century, which are often large but with high error, and the Gutenberg-Richter function for recorded earthquakes and using the statistical method of maximum likelihood estimation. In this method, it is also possible to simultaneously use historical and recorded earthquakes by making appropriate classifications by considering the magnitude error, threshold magnitude, and maximum magnitude differently for each category. It is also possible to somehow include the effect of seismic absences or lack of information in the calculations. The estimated seismicity parameters, including the maximum magnitude of the earthquake (Mmax), the coefficient β and the annual volume λ in the 100 km area using the Kijko method, are:Mmax=7.7, β=1.86, λ=0.9The probability of the event or return period of earthquakes is another parameter that are calculated by this software. The return period increases greatly with the increase and the probability of an earthquake event decreases in a certain period of time. For example, in a 100-year period, the probability of an earthquake with a magnitude of 6 is 90%.

Graphs show an increase in the return period of earthquakes, so the probability of an earthquake event in a certain period of time decreases. Earthquake risk map for PGA was performed on bedrock with 1% damping for a return period of 475 years in a set of networked points at 0.05 ° × 0.05 intervals. According to the acceleration set for the city of Ardabil, this area is divided into 4 micro-zones. The results show that the acceleration values ​​in this range for PGA vary from 0.19 in the north to 0.21 in the southwest. It should be noted that the acceleration values ​​are the same throughout each designated area, so the city of Ardabil can be introduced as one of the cities with moderate risk in seismic activity.

Migmatites are silisic rocks form in middle to high degree metamorphic territories, at lower to middle continental crust and through water producing reactions (Makrygina, 1977; Brown, 1979; Ashworth, 1985). During intrusion of Chah-Bazargan batholith in the Barrovian-type Qori-Neyriz regional metamorphic rocks at 170 Ma (Fazlnia, 2017), some pieces of these rocks were trapped in the magma and endured intense metamorphism and anatexis. They show stromatic and nebulitic magmatic structures. In the present study, the stable mineral assemblages, conditions, and factors affected partial melting in the Chah-Bazargan migmatites are investigated using phase diagrams and petrographic evidence.

The nebulitic migmatites representing the highest metamorphic degree and close and gradational relationships with peraluminous granites in the area were sampled. Petrographic studies were performed on the thin sections to determine mineral assemblages of peak metamorphic condition. The phase diagrams were calculated using whole-rock analyses reported in Fazlnia (2017) and TheriakDomino software (de Capitani, 2010).

PetrographyThe main textures of nebulitic migmatites are granoblastic and poikilioblastic, although porphyroblastic texture can be observed in places. Stabe mineral assemblage cordierite + spinel + garnet + prtithic K-feldspar + plagioclase together with dissolved silimanites and biotites inclusions represent the peak metamorphic condition. Corundum + spinel sympetectic around the cordierites also form in high metamorphic degrees (Whittington et al, 1998). With increasing metamorphic degree, the biotites and cordierites become less and the more, respectively.Phase diagramsThe P-T phase diagram was calculated in Na2O-CaO-K2O-FeO-MgO-SiO2-H2O (NCKFMASH) chemical system with fluid as pure water and in excess. According to it, mineral assemblage feldspar + chlorite + biotite + muscovite + quartz was stable at temperatures below 550 °C and represents hornblende hornfels zone of the area metapelitic rocks. Partial melting occurs at 700 that increases up to 750 °C with pressure increasing. The assemblage feldspar + garnet + biotite + cordierite + quartz melt + H2O observed in the xenoliths occurs a pressures below 5 kbar. Although, comparing calculated almandin isopleth for garnet and phlogopite for biotite with chemical compositions of these minerals represented in Fazlnia (2017) indicates that anatexis could onset in lower temperatures.According to the calculated T-XCO2 diagram, the partial melting occurs in lower temperatures with increasing in CO2 content of the fluid. Also, T-XO2 diagram show that presence of sufficient O2 in the environment could decrease the partial melting temperatre to below 700 °C. Moreover, the T-Mg# diagram (Mg# = MgO/MgO+FeO) reveals that low Mg# contents of these rocks (0.2 – 0.3) could trigger anatexis in temperatures below 700 °C.

Falling of metapelitic xenoliths in Chah-Bazargan batholith producing magma caused intense contact metamorphism and partial melting. In the peak condition, the assemblage cordierite + spinel + K-feldspar + garnet + palgiocasle together with corundum + spinel intergrowth on cordierite formed. Based on the calculated phase diagrams, anatexis occured in temperatures 700 – 750 °C and pressures less than 5 kbar, however, chemical compositions of the garnets and biotites from the xenoliths show that it could onset in lower temperatures. The T-XCO2, T-XO2, T-Mg# diagrams reveal that increasing CO2 and O2 and high FeO contents of the protolith probably triggered anatexis in lower temperatures.

Today, the conversion of old and abandoned mines into a tourist complex with titles such as geoparks has become a topic of the day in the word. There are also many abandoned mines in Iran that At least some of them can be converted into tourist destinations and contribute to the livelihood of local communities. The subject of this article is to study the characteristics of Konijkola historical coal mine in Ziraab city, especially Shahtunnel in Shahid Beheshti University, in order to establish a mining -museum park with the aim of planing and entrepreneurial that located in Talar watershed.
For this study, a descriptive-analytical method was used and all available documents from about 1320 until now in the archives of Central Alborz Coal Company and also oral interviews with managers, experts, engineers and retired technical workers were used to obtain the necessary historical information. In addition, with extensive fieldwork, this information was mapped, reconstructed, and purposefully analyzed to establish a mining -museum park.
The ShahTunnel, its outer area and other facilities were defined as mining- museum park. In this research, the aim is to change the use of the tunnel and its grounds to create geotourism and a mining- museum park while preserving the mining heritage. In order to turn the Shahtunnel into a suitable underground space for mining tourism, it is necessary to make the cross section of the tunnel bigger and the arc tube to be 7.3. Traffic can be done both on foot and by mining wagon. In addition, at a distance of 350 meters from the mouth of the Shahtunnel, a 90-meter-long underground space with a cross section of 13.8 arc should be designed and excavated in order to establish a suitable place for exhibition and store of stones, fossils and mineral artifacts. Also, Farvardin tunnel in the east of Shah tunnel with a length of 150 meters needs to be reconstructed and repaired. For ventilation of Shahtunnel and Farvardin tunnel, a CBM6 fan device, a CBM5 fan device and air conditioning tarpaulin are required, respectively. The total length of Farvardin tunnel, Shah tunnel and the connecting tunnel of these two is 900 meters. Due to the location of this mining- museum park within the boundaries of Shahid Beheshti University, the scientific aspect of this tourism complex will quickly be in the minds and will quickly become a national, regional or even global brand.
The area of the outer ground of Shahtunnel, including natural resources, is 32 000 square meters, which can be divided into 4 blocks in terms of geotourism and mining- museum park. Block No. 1 is located on the northwestern front of the mining- museum park and its main components include the entrance, tourist guide, construction of a parking lot and office building, and design of sidewalks in the direction of the coal shot. Block No. 2 is located in the western part of Zabhdarreh River and the capabilities of this block include sidewalks with slate stones of mines, marginalization of the river with native stones, installation of plaques on stone outcrops and trees for training and environmental knowledge and design of the space inside the tunnel for the exhibition and mineral products store. Block 3 is located in the east of the river and includes a museum to display the old mining facilities, mining tools and a specialized library with wood and stone materials and in accordance with the local architecture of the region. The main components of block number 4 are the hotel, accommodation suite and market.

According to the outcrops of volcanic and intrusive rocks with different compositions and ages in the northwest of Iran, the magmatism of the northwest of Iran has been introduced under the titles of Talash and Arsbaran tectonomagmatic zone (Berberian, 1981; Aghazadeh et al, 2010, 2011; Castro et al, 2013). The Talash zone in the east of the Western Alborz-Azerbaijan zone, like the rest of Azerbaijan and Urmia-Dakhtar magmatism, has experienced the peak of magmatism in the Eocene to Oligomiocene (Vincent et al, 2005; Shafaii Moghadam and Shahbazi Shiran, 2010). Volcanic rocks in the northeast of Lahrud are andesitic, basaltic eruptive outcrops and plutonic internal alkaline, calc-alkaline and Shoshonitic masses (Vincent et al, 2005), which continue to spread significantly beyond the borders of the country. Eocene volcanic rocks are seen in the 1:100,000 maps of Lahrud with a northwest-southeast trend. In this research, the lithological, geochemical and petrogenesis characteristics of volcanic rocks in the north of Lahrood in the Khanali Daresi section have been evaluated.
Volcanic rock outcrops in the study area were first evaluated in the field and 45 samples were taken from different parts and then 20 thin sections were prepared from the samples for petrographically studies by using an Olympus type polarizing microscope. Then 11 fresh samples were sent to MS Analytical Laboratory in Canada by Zaminriz Kavan company for chemical analysis and determining the main oxides of whole rock.
Eocene- trachy-andesite and trachy andesy basaltic rocks in northwestern Iran, north of Lahroud (Ardabil province), Extruded with northwest-southeast trend. These rocks have hyalomicrolith porphyritic textures and have plagioclase as major minerals with minor amphibole, pyroxene, biotite and opaque minerals and alkali feldspar minerals. The productive magmas of these rocks are of potassic and shoshonitic nature of Roman type. The parent magma of these volcanic rocks is affected by the fractional crystallization process and Eu / Eu * ≤ values (0.83 to 1.08) indicate plagioclase separation in the magmatic reservoir. Negative anomaly of Ta Ti, Nb in the spider diagrams and enrichment of the LILE and LREE index indicate the effect of subduction environments component in generation of g these rocks. Ba / Nb ratios of 45 to 131, La / Sm ratios of N above 2 and Th / Ce ratios of 0.13 to 0.2 indicate enrichment correlations with melting of subducted sediments during subduction. Also, low Ba / Rb ratios from 0.10 to 15.2 and Rb / Sr ratios from 0.07 to 0.1 indicate melting of phlogopitic bearing source with shoshonitic nature in genesis of these rocks. primary magmas of these rocks form from partial melting of less than 10% matosomatized phlegopolite bearing spinel- lherzolite source and melting of magmatic subduction sediments during subduction in the post-Collisional setting.
 
The geochemical characteristics of the studied samples indicate their enrichment and formation in connection with the subduction environment. This indicates a continental volcanic arc in the experimental diagrams of determining the tectonic environment. The primary magma of volcanic rocks consists of the melting of less than 10% of spinel-phlogopite mantle and metasomatized with subduction factors and associated sediments.

Mazraeh deposit is located at 20 Km north of Ahar, Eastern Azerbaijan, North-West of Iran. The area is situated in the Western Alborz – Azerbaijan geotectonic zone. Intrusion of the Oligocene – Miocene Sheyvardaagh batholith in to the older carbonate and volcanoclastic rocks is responsible for contact metamorphism, contact metasomatic mineralization, and formation of schist, hornfels, marble and epidote - garnet Skarn. This batholith is a subduction-related calc to sub alkaline, peralominous and S-type granitoids. Due to the extensive Tertiary magmatism, skarnization and extensive alterations, this zone is one of the remarkable Fe, Au, Cu-mineralization in Iran. Therefore, a lots of research and investigations have been done by the Geological Survey of Iran and different government and private companies. The following paper is results of our research about Cu -Fe- Au skran mineralization in the Mazreh area, NW of Iran.

This research was conducted in two parts, field and laboratory analysises. In the field section, after carrying out geological surveys and detailed examination of 6800 meters of drilling cores from 61 boreholes, a total of 60 samples were chosen from 21 selected typical boreholes of different sizes. About 36 samples from intrusive rocks choosed to preparing thin sections for petrographic studies and major chemical analysis by XRF. Also, 24 samples from mineralized zones were selected for preparation of polished sections, mineralographical study and geochemical analysis by ICP-OES.

Major alterations are chloritic, propilitic and sericitic which have close genetic relationship to mineralization zone. The main mineralization stage occurs as exoskarn in garnet-epidote skarn type. The major rock forming minerals in the skarn are garnet (adradite and grossularite), epidote, actinolite, chlorite, biotite, sericite and amphibole. Mineralogical paragenesis consists of magnetite, pyrite and copper sulfides such as chalcopyrite, bornite and covellite, hematite (especularite), goethite and malachite. The mineralization is vein, veinlet and disseminated type. The main mineralization stage occurs in retrograde skarn. Average value of Cu is 16284 ppm, FeOt 35.05 percent, Au 3380 ppb and Ag 9.94 ppm. There is no correlation between the values of Au and Cu as well as Ag and Au with S. It seems that Au mineralization is not simultaneous with Cu skarn mineralization but Ag mineralization is simultaneous with skarn phase. The geological, mineralogical and geochemical data show that the granitoid batholith of Mazraeh area is a fertile pluton with Cu – Fe-Au skarn mineralization.

The mineralogical and geochemical data show that Sheyvardaagh batholith intrusive rocks are S-type and inlmenite series. Tectonomagmatic setting of these granitoid batholith lies within subduction-related calc to sub alkaline, peralominous and S-type granitoids. A/NK and A/CNK diagram shows these granitoids are close to fertile Fe-Cu-Au granitoid batholith and related skarn. The geological, mineralogical and geochemical data show that the granitoid batholith of Mazraeh area is a fertile pluton with Cu – Fe-Au skarn mineralization.

We would like to express our gratitude to the management and respected staff of research and development affairs of the National Copper Industries of Iran (Sarchshme) for supporting of this research and to the staff of the National Copper Company located in Ahar and Warzghan cities for their cooperation in the field visit and sampling.

Controlling industrial pollution sources in order to protect the environment is one of the management strategies in the path of achieving sustainable development, which requires predicting the concentration of pollutants in a specific radius of the chimney and mathematical models can be similar. Air pollution is one of the most important environmental problems in industrial areas and its release from the chimney and its distribution in the atmosphere of any area causes serious damage to the ecosystem of adjacent lands. In point pollution sources such as chimneys of industries and refineries, the spread of pollutants depends on factors such as physicochemical properties of the emitted material, chimney characteristics, meteorological conditions and surface topology.
In the present study, in order to achieve this approach in the middle mountain plain of Tabriz, the concentration of pollutants emitted from 20 chimneys of Tabriz oil refinery with AERMOD model for a radius of 10 km was predicted. In this study, using meteorological data, land use layer, digital elevation model and chimney characteristics, distribution and concentration of pollutants from the chimneys of Tabriz oil refinery including SO2, NO2, CO and PM2.5 was predicted using the AERMOD model. The AERMOD model is a permanent state distribution model that can be used to determine the concentration of various pollutants in urban and suburban areas. The AERMOD model has two modules including AERMET and AERMAP. The AERMET module is related to the preparation of meteorological and land use data files and the AERMAP module is related to the characteristics of the chimney, pollutants and the digital elevation model. AERMET module data include wind direction and speed, cloud cover, relative humidity and surface air temperature (2 meters above the ground) in a period of one hour, which is in the range of meteorological data of Tabriz Synoptic Station in the interval Estimated time from 2010 to 2020. Using the information provided in the two modules, the distribution of pollutants from the chimneys were calculated using the AERMOD model.
Annual wind rose plot showed that the dominant wind is from the east and the first-degree wind is from the west. The results of the model prediction showed that the concentration of CO 8h was 0.5 to 20 ug/m3; The concentrations of SO2 and NO2 1h were between 5 and 100 ug/m3, and the concentration of PM2.5 24h was between 0.5 and 10 ug/m3, which were less than standard emit. East winds transfer pollutants to the northern of the Sahand, southwest of the oil refinery, and accumulate at altitudes of less than 1500 meters. The highest concentration of atmospheric pollutants is in Kheljan city in the southwest of Tabriz oil refinery and prevailing winds have caused the pollutants to move away from Tabriz plain and not have much impact on the environmental ecosystem of Tabriz plain. Pollutants under the influence of prevailing winds, have accumulated in the northern foothills of Sahand and in the southwestern part of Tabriz oil refinery and their maximum limit is in the range of 1450 to 1500 meters, but from this level (1500 m altitude) onwards, as the altitude of the place increases, the concentration of air pollutants decreases. Due to the establishment of the boundary layer, the maximum concentration of air pollutants is at an altitude of 1450 to 1500 meters in the southern foothills, from which the concentration of gases and suspended particles from the chimney is reduced.
In the mid-mountain plain of Tabriz, the concentration of pollutants leaving the chimneys of the oil refinery is less than the standard limit and does not have much effect on various ecologies and ecosystems. Due to the presence of prevailing east winds, the maximum concentration of gaseous pollutants and particulate matter in the northern foothills of Sahand and in the ambient air of Khaljan urban settlement and the wind has caused pollutants from the city of Tabriz, which is located east of the oil refinery. It is moving away and flowing to the southern mountains, and in the metropolis of Tabriz, these pollutants are very low.

The ozone is produced and destroyed by photochemical reactions between highly energetic ultraviolet photons and some gas species present in the stratosphere, especially the oxygen. Ozone was identified in the atmosphere by Schonbein (1867) and Chapman (1930) formulated the first set of chemical reactions in an attempt to explain the existence of an ozone vertical structure (Madhu, 2016). Ozone formation starts when a highly energetic photon coming from the sun with wavelength shorter than 242 nm dissociates an oxygen molecule resulting in two atoms of monoatomic oxygen (Langematz, 2019). Then given the high reactivity of atomic oxygen, these atoms quickly react between each other to form ozone. The ozone effectively absorbs the highly energetic ultraviolet radiation. The result of this absorption is the dissociation of ozone in molecular and atomic oxygen for wavelength shorter than 325 nm (Castillon, 2014; Douglass et al, 2014). Ozone is also destroyed through the recombination with atomic oxygen. The set of mechanisms presented above represent the Chapman Cycle. Atmospheric dynamics is known to be a major factor in the variability of stratospheric ozone distribution over the tropics from year to year. There is considerable evidence that the atmospheric total ozone amount is strongly influenced by the stratospheric circulation. Ozone is first formed in the tropical troposphere and then transported to the tropical stratosphere using Brewer-Dobson circulation. This circulation, systematically transports ozone from tropics to the middle and high latitudes (Gerber, 2012). Stratospheric sudden warming (SSWs) is a violent phenomenon in the winter polar region (Kodera, 2006). In a minor warming the temperature gradient reverses over a range of altitude at or below 10hPa and zonal wind at 10hPa is weakens but does not change its direction. When a major sudden stratospheric warming’s events occur, the zonal mean temperature at 10hPa around the polar cap for latitudes north of 60°N suddenly rises and increases by the 25K over period of several days and zonal-mean zonal wind reversal at 10hPa and 60oN during the winter from November to March (Moradi,1399). In this paper five major SSWs, one minor SSWs and one year without SSWs events were considered to study the variability of total column ozone over the polar cap region.

In this study we have used the daily mean data from the Modern Era Retrospective Analysis for Research and Applications version 2 (MERRA2) and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) assimilated data. From the MERRA2 data, zonal wind and temperature were obtained at 10hPa and total column ozone from 01 July 1991 to 30 Jun 1992 (1987-1987, 2008-2009, 2010-2011, 2012-20113, 2016-2017 and 2017-2018). The zonal mean temperature (total column ozone) averaged around the polar cap for latitudes north of 60°N (63°N). This is a good measure of the overall temperature and total column ozone content in the polar vortex. The average east-west (zonal) wind speed for 60°N. This is near the peak of the polar jet maximum. The study region covers 0.0° to 357.5° geographical longitudes and 60°N to 90°N geographical latitudes. From the NCEP/NCAR data, zonal wind and temperature daily were presented by a horizontal resolution of 2.5° ×2.5° at 10hPa in region study at different case studies and averaged from 0.0 to 357.5o geographical longitudes around the 60°N to 90°N geographical latitudes. To study the distribution of total column ozone during the sudden stratospheric warming events, five major SSWs, one minor SSWs and one year without SSWs events were identified (Table 1). To represent the total column ozone variations during the sudden stratospheric warming; the daily total column ozone in this cases are analyzed. Table 1. Characteristics of sudden stratospheric warmingRowYear tYPEDuration (days)growth(day)maturation(day)decline (day)12010-2011Without  SSWs----21991-1992Minor18---31986-1987Major6637171242016-201712110152012-2013296121062017-2018291221572008-20094616426 

The results showed that the during the five major SSWs events (one minor SSWs and one year without SSWs evens), total ozone column over polar cap region is increases (decrease) and the anomaly of this quantity is always positive (negative) compared to the long-term average. Furthermore, in during major SSWs events there observed an increase of 29-70 DU in total ozone column from the average value over the pole cap and if the major SSWs is strong total ozone is found to rise by 99-104 DU. The positive anomaly total column ozone in the polar cap is more in growth and maturation of the major SSWs and less in the period of decline. The longer the growth and maturation period and the faster of reduce of the zonal mean zonal flow, the positive anomaly total column ozone is higher. During the period of growth and maturation of major SSWs, the polar vortex and night jet are rapidly weakened, and total column ozone is better transferred from the equatorial stratosphere to the polar cap by the Brewer-Dobson circulation. During the major SSWs that warming of stratosphere, diabetic cooling on the Brewer-Dobson extra tropical down welling branch also weakens. This mechanism also increases the ozone of the polar cap by reducing the rate of ozone depletion.

In this study, the variation of polar cap total column ozone during one minor SSWs case (1991-1992), five major SSWs cases (1987-1987, 2008-2009, 2012-20113, 2016-2017, 2017-2018) and one year without SSWs events (2010-2011) was analyzed over the polar cap region. The results showed that the during the five major SSWs events (one minor SSWs and one year without SSWs evens), total ozone column over polar cap region is increases (decrease) and the anomaly of this quantity is always positive (negative) compared to the long-term average. During the major SSWs that warming of stratosphere, diabetic cooling on the Brewer-Dobson extra tropical down welling branch also weakens. This mechanism also increases the ozone of the polar cap by reducing the rate of ozone depletion.

Historical fabric generally refers to the part of a city in which most of the structure remain but the elements, components and spaces have changed. In Iranian cities, historical fabric refer to the part of urban fabric that have been formed before 1920s.  Preserving these areas plays an important role in societies' awareness of the past and cultural values, and can evoke national pride, a sense of identity and a sense of belonging in citizens. This precious human heritage has been exposed to various damages over time and many of them have been destroyed. Although the emergence of Tehran as a city in Iran does not take long, but during these two and a half centuries, many precious buildings have emerged under the influence of the ancient culture of Iran and the glory of Islamic-Iranian architecture and urban planning. Due to the irrationality of irrational urban plans, lack of protection and maintenance against events and renovations and buildings renovation or due to inappropriate interventions and restorations, an important part of Tehran heritages has been deteriorated. This paper aimed to investigate the factors threatened Tehran historical fabric

This is a descriptive-analytical research. The data are in three categories. The first category of data taken from documentary sources such as GIS data set of 2016 Iranian Public Census of Population and Housing, Tehran’s land use, and Tehran worn-our fabric. The second category including survey data from the research project of Neighborhood Sustainable Development Document of Tehran, and the third is the evaluation was conducted by 15 experts.  In order to describe and compare the data, survey data were converted to percentage scale. The first and third category data were also were matched with the second category data according to the expert’s opinion. Then resilience map of the neighborhoods has been drawn and analyzed using GIS tools.  The study area is the historical fabric of Tehran, which is known as the Nasiri fence area. It has an area of about 1,500 hectares and was once enclosed in an octagonal wall was built in 1905. This area currently includes 21 neighborhoods.

One of the risk factors for the Tehran historical fabric is the high probability of occurring devastating earthquakes. In the earthquake risk zoning maps, it lies in a high-risk zone. Tehran has suffered from devastating earthquakes in the years 300 BC, 743, 851, 855, 958, 1177, 1384, 1830 and 1930 AD. Subsidence is also an emerging risk. Digging underground tunnels for city trains, subsidence of old aqueduct canals that have passed through historical sites in particular, extraction of groundwater and the fall of aquifers, the collapse of old sewage absorption wells is among the factors for the occurrence of this phenomenon in the city. The worned-out buildings which cover a relatively vast surface area indicate high vulnerability of the study area. In more than one third of the neighborhoods, more than half of the buildings area is considered as worn- out and in the neighborhoods of Agahi, Harandi, Rah Ahan and Foroozesh, more than 80% of the area is defined as worn -out fabric. Overcrowding can cause more vulnerability. In the neighborhoods of Pamanar, Ferdowsi, Sirus, Baharestan and Sheikh Hadi, the population density is lower than 100 and even in Pamanar neighborhood is 16.7 people per hectare. However, according to unofficial estimates, the daily population of these neighborhoods is even up to 10 times namely more than 1000 people per hectare. High proportion of tenants usually indicates greater vulnerability. In the historical fabric, in general, the proportion of tenants is high. In Darvazeh Shemiran and Harandi neighborhoods, only 23.4% and 32.4% of households live in their own homes, respectively. In two-thirds of neighborhoods, the proportion of tenants is more than 50%. Awareness and appreciation of cultural heritage can be an important factor in enabling public participation in the preservation and protection of heritage. While in the Ferdowsi neighborhood, more than 85% appreciated their neighborhood's cultural heritage, in some neighborhoods, such as Agahi and Rah Ahan, this was close to zero, indicating a lack of awareness. This is normal for Ferdowsi neighborhood due to its location near the three most important universities of Iran. The figure of 2.7 indicates the average vulnerability of the historical fabric. Meanwhile, four neighborhoods of Pamanar, Baharestan, Ferdowsi and Emamzadeh Yahya, which have more important historical monuments, have higher vulnerability. Central neighborhoods in the study area are more vulnerable than peripheral neighborhoods.

Urban historical fabric is a legacy of the past and a link among people and their ancestors. If the cultural heritage disappears from the cities, the link with the past will be disconnected which leads to cities’ loss of identity. Therefore, protecting this heritage from destruction and damage is considered to be a very important and vital task. It is worthwhile for trade and political-administrative functions of the historical fabric to be adjusted and organized, and also for its residential function to be revived and strengthened. Paying attention to cultural heritage requires a holistic approach that encompasses complex concepts as social, cultural, historical, artistic and architectural, economic, urban planning, and sustainable development. However, cultural heritage protection should not only include the capacity to withstand wear and tear over time without losing credibility and usability, but should also pay attention to the capacity of heritage resistant to natural hazards. In the meantime, preventive protection to maintain the historical fabric should be a priority.

In the field of regional synergistic development, synergy is defined as the cooperation, interaction, and benefit of subsystems from the benefits of interactions. Synergy is achieved through collaboration and complementarity and requires a high level of interaction to create the necessary network correlations to compensate for interdependence. Hence, regional synergy refers to regional cooperation, close communication, and continuity of interaction. Therefore, it can be said that regional amplification is the interaction between regions and a combination of cooperation and competition between regions, which aims to achieve an optimal system in which the effects of two or more structures or functions of a partner and each other. Consistently more than the sum of the effects of individual components and functions alone, various studies have explored the concept of synergy in the development of multicenter regions, ecosystems and energy, social theories, national and regional innovation systems, and economies of scale. Urban accumulation, regional growth, business development, have been used. But what has not been evaluated is the application of this concept in the field of economic development, especially in metropolitan areas of developing countries, which are still involved in imbalance, lack of integration, functional coherence and unbalanced distribution of activities. The metropolitan area of ​​Tehran is no exception to this rule. Due to the significant concentration of manpower, resources and economic enterprises, this region is known as the beating heart of the country, which can play the role of a locomotive and railroad for national development.

The research method is quantitative. The research index has been determined according to the theoretical foundations and research background. To conduct the research, about twelve thousand companies were located in the metropolitan area of Tehran based on 28 active ISIC codes. Then, the flow of goods between the cities of the region was collected and analyzed based on the information of the Road Authority using network analysis. In order to analyze the internal relations of firms, based on the output data table, the two-region method was prepared and the relations between manufacturing firms were evaluated.

The study of industry specialization shows that the activities of radio, television and communication devices, energy production, computer and engineering activities, tobacco products and mining have the highest level of specialization over a period of twenty years. On the other hand, the study of the degree of specialization of activities shows that the coefficient of specialization of activities has decreased. This means that the cities of the province have a tendency towards similarity in industrial activities, which creates the ground for increasing synergy. A study of the spatial distribution of industries in 1975 shows that food and beverage products, other non-metallic mineral products, fabric metal products, rubber and plastic products have the most homogeneous spatial distribution in the metropolitan area, respectively. In 1995, the spatial distribution of industries tended to be more balanced, and thirteen disciplines of industrial activity tended to be more balanced in the region. Fabric metal products, construction of machinery and equipment, rubber and plastic products, food and beverages have the highest spatial balance between industries in the metropolitan area. Spatial analysis of industrial enterprises shows that the industrial enterprises of the province, affected by the factor of access and mobility of production factors, tend to disperse. In other words, the expansion of industries corresponding to the expansion of the communication network has taken place, and the returns caused by the scale in the cities of Rey, Karaj, Savojbolagh, Pakdasht, next to Tehran, have attracted economic enterprises to these cities. In terms of spatial concentration of employment, in 1996, the city of Tehran had 84% of the employment of industrial enterprises, which after two decades, this amount has decreased and reached 45.42%. In contrast, the share of other cities in the metropolitan area of ​​Rey (9/22), Karaj (8/04), Pakdasht (6/86) and Savojbolagh (6/27) has increased. The study of the degree of clustering of economic activities in the metropolitan area shows that food and beverage products, other non-metallic mineral products, construction of machinery and equipment, machinery and electrical appliances, metal fabric products, manufacturing Chemical materials and products, rubber and plastic products, medical tools, optics, textiles, have the highest rate of spatial clustering among the industrial enterprises of the province, respectively. The study of employment of industrial enterprises shows that ten fields of industrial activity constitute about 80% of employment and 78% of the number of industrial workshops in the province.

The results show that the metropolitan area of ​​Tehran has various economic and spatial capabilities to achieve economic development. Examination of indicators such as specialization, centralism, accumulation, diversity and clustering as a result of synergy shows that if the desired policies in this area of ​​the metropolitan area, the ability It plays an irreplaceable role in the development of the national economy. The study of the place specialization index shows that Tehran is still known as the most specialized city in the metropolitan area. However, over time, other cities have also increased in terms of specialization. The distribution of manufacturing enterprises in the region, according to Moran statistics, shows that after two decades, the spatial distribution of enterprises tends to become clustered. In addition, the spatial distribution of enterprises has been in line with the trend of expanding the communication axes of metropolitan areas. In examining the space accumulation index, which analyzes the situation of the whole industry with respect to continuous space, they tend to be one-sided.