Journal of Spatial Analysis

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Risk Assessment of Selected Path Railway between Isfahan and Ahvaz against Earthquake. Journal of Spatial Analysis Environmental Hazards 2018; 4 (4) :19-32
URL: http://jsaeh.khu.ac.ir/article-1-2574-en.html

The earthquake is a natural disaster that damages structure and lifeline and is simply inserted into human artifacts. For this reason the structures and lifeline, earthquake loads shall estimate and in order to provide its design.in Iran earthquake, risk of natural disasters is dominant. It should be noted that Iran in recent years, an earthquake with a magnitude of 7.5 Richter scale or more frequently experienced. Focus most historical and instrumental earthquake along the northern margin of two young belts (Kope-Dagh and Alborz Mountain) and south (Zagros Mountains to the northwest - southeast) is located. The relative risk of different regions in the 2800 earthquake building and Housing Research Center Indicate that is about 73 percent of the main lines of the rail network in the regions with high relative risk and especially the Zagros mountain areas are the greater risk of earthquake. Construction of railway lines between Esfahan and Ahvaz on stage in this research study that evaluated against earthquake risk path it has selected. The research study also Zagros mountain interval passes and bridges, tunnels and numerous curves.
Rail between the two cities Esfahan and Ahvaz is studied.  In the years between 1050- 2011, more than 350 earthquakes occurred in the area, the biggest earthquake with a magnitude of 6.8 Richter scale in 1384 had the highest value. In this area there are 615 fault reverse fault Zagros Iran’s biggest fault zones perpendicular to that direction. Distinguishing feature of this exist geomorphologic unit including   high Zagross (Lordegan - Brojen), Zagross folded (Baghmalek - Lordeghan) and Khuzestan plain (Ramhormoz - Ahvaz), in addition to different geological units covers. The beginning and end of the range in a wide range of railroad in Ahvaz not consolidate the young sedimentary soils passes, the diversity of geological formations in the Zagros that most of the sedimentary formations have been broken by numerous faults. Based seismic study in the south Zagros bar is located. In this study evaluated the risk period.
The data used in this study are planned rail route Esfahan – Ahvaz  scale 1:250000 preparation of the Islamic republic of Iran railway research center, geological maps 1:100000  the geological survey Iran, satellite images IRS LISS III  the armed forces geographical organization, historical and device earthquake data geological survey. Thus, in the first stages of investigation historical and device earthquake based on semivariogram model and Kriging interpolation method, historical and device earthquake zones calculated. Fault lines of, geological maps 1:100000  mining and were used; of aster the 30 meter resolution ,slope ,Curvature, Profile, elevation it was prepared; lineaments, rippling unit, land use and vegetation cover of satellite images IRS LISS III it was prepared. For the analysis of variable composition due to the lack of homogeneity in terms of scale, the need to unify them was based on the degree of membership. Then, based on Gaussian fuzzy membership function was adjusted. In this study, sure to select the correct of gamma, merging were the values0.7, 0.8, 0.9 and 0.95. Then, were evaluated by Statistical Zone and select suitable gamma.
Obtained seismic zones on the basis of semivariogram model and Kriging interpolation method showed that rail lines in three intervals smaller than 4 Richter scale earthquake is facing. Whereas earthquake greater than 4.5 Richter scale on quaternary alluvial deposits are located, in addition to its range with a maximum magnitude of earthquakes on faults and lineaments as well as difference corresponded to the sudden formation. The case study is Iran’s biggest fault zones and more than 350 earthquakes occurred the 1000 year that adaptation layers fault, earthquakes and also historical earthquakes, indicates active region in terms of earthquake. Using a combination of variables of overlapping functions vegetation cover density, land use, historical earthquakes,4-5 earthquakes, greater than 5 earthquakes, change height level layer, slope, Curvature, Profile, faults and lineaments and drainage density layers; the amount of risk  in gamma0.8 earthquake was detected because the results showed that recent gamma have greatest difference between variables and classes risk. Zoning in 4 commodity risk respectively without risk, medium risk, high risk and very high risk classified and two long range and a short interval of railway on the scope of their compliance with the maximum risk.
 
The results show that in terms of topography, geology and system faults and joints related fractures there are tremendous diversity that diversity causes the damage of the earthquake differently. In other words proved to be highly destructive earthquake with magnitude of this range is different. Most gender diversity in both land and exposed the fault lines pass through the system, is one of the Shareza to Ardekan and other the Ramhormoz to Baghmalek. So magnitude earthquake in rail track will be a lot of changes. The beginning and end of the rail passes of new alluvial sediments lands due to being detached and empty spaces, the near Esfahan and Ahvaz areas are involved in the escalation vulnerability. Deposits range in the vicinity Gandoman and of wheat rail lines Izeh the screw with range of motion will face intensified by the earthquake.  There convex reflects of Dizajan to Izeh intensification of earthquake in vulnerable parts of the range. Seismic records of more than 5 Richter scale and shallow depth because of lack of data has little effect the result of risk that need to be considered as evidence of potential risk.