| چکیده انگلیسی مقاله |
Abstract
Earthquakes are among the most devastating natural disasters, causing significant damage to human society. Therefore, assessing seismic vulnerability and developing strategies to mitigate this risk are critical issues today. Abdanan County located in southern Ilam Province is particularly susceptible to earthquakes due to numerous fault lines, a history of destructive seismic events, and inadequate adherence to safety standards. This study aimed to measure and evaluate the earthquake vulnerability of the county. To conduct this research, we first prepared digital layers representing the factors influencing earthquake occurrences. We then standardized the criteria maps using fuzzy membership functions and weighted the criteria through the CRITIC method. Finally, we employed the multi-criteria analysis method of ARAS to create a zoning map with 5 vulnerability levels. The results indicated that the most significant variables affecting vulnerability were the distance from the earthquake epicenter (weight: 0.153), land use (0.133), geological formation (0.130), and distance from faults (0.125). According to our findings, approximately 22.20 to 30.35% of the county’s total area fell within the very high vulnerability category. Additionally, the cities of Abdanan, Murmuri, and Sarab Bagh, along with 40 villages, were classified as having very high vulnerability, while 16 villages were categorized as highly vulnerable. Furthermore, using the rock curve method and a sub-curve level of 0.80, we found that the accuracy of the ARAS method in identifying and zoning the vulnerable areas of Abdanan County in relation to earthquake risk was very promising.
Keywords: Hazard, Earthquake, Multi-Criteria Analysis, Geographic Information System (GIS).
Introduction
Earthquakes are among the most destructive natural disasters, consistently inflicting severe damage on human society. According to United Nations reports, earthquakes are the most significant natural disaster in Iran, with a catastrophic event occurring approximately every 10 years, resulting in widespread homelessness and loss of life (Mohammadpour, 2019, p. 78). Creating a zoning map to assess residential vulnerability to earthquakes is an effective method for identifying at-risk areas (Heidarimozaffar & Tajbakhshian, 2022, p. 75). In this study, we focused on zoning the vulnerability of settlements in Abdanan County to earthquake risk, employing the ARAS multi-criteria algorithm to accurately estimate the seismic risk in this region using both spatial and descriptive data.
Materials & Methods
This study was applied in nature and employed a research methodology that integrated data analysis, Geographic Information Systems (GIS), and multi-criteria analysis techniques. We utilized ArcGIS, Idrisi, and Excel software for image processing and data analysis. To assess earthquake hazards, we first identified the key factors influencing vulnerability, including slope, Digital Elevation Model (DEM), geology, land use, distance from the epicenter of previous earthquakes, proximity to communication routes, distance from population centers (both cities and villages), distance from rivers, and distance from fault lines. Next, we prepared information layers corresponding to each factor within the GIS environment. Standardization of these layers was performed using fuzzy membership functions, while factor weighting was conducted using the CRITIC method. The final analysis was carried out using the ARAS multi-criteria method. After developing the vulnerability map for Abdanan County regarding earthquake risk, we evaluated the model’s accuracy using the ROC curve.
Research Findings
The results from the ARAS method indicated that 531.12 km2 of the total area of Abdanan County fell into the very high vulnerability category, while 726.22 km2 was classified as high vulnerability. Additionally, 687.50 km2 exhibited medium vulnerability potential. Meanwhile, 336.89 and 110.99 km2 were categorized as having low and relatively low vulnerability potential, respectively. A comparative analysis of altitude and slope factors against the final vulnerability map revealed that these at-risk areas spanned various altitudes, ranging from 200 to 2000 m and slope classes from 5° to 80°. In terms of land use, residential areas, agricultural land, forest coverage, and medium pastures constituted the majority of regions with high and very high vulnerability potential. When comparing the distance from population centers to the zoning map, it became evident that vulnerable areas were situated within 0 to 1000 m of these centers. Regarding the distance from communication routes, regions with high vulnerability potential were typically located farther away, between 1000 and 5000 m from these routes. Additionally, the analysis of proximity to rivers indicated that highly vulnerable areas were found within close range, specifically 0 to 800 m from water sources. Notably, the population density of cities and villages tended to cluster near these water sources. Furthermore, areas classified as having very high and high vulnerability were located in close proximity to previous seismic foci, particularly within 0 to 1000 m of these sites.
Discussion of Results & Conclusion
The findings of this study indicated that the most significant factors influencing earthquake occurrence in the study area were distance from the epicenter, land use, geological formation, and distance from fault lines. Our analysis revealed that approximately 22.20 and 30.35% of the total area of Abdanan County fell within the very high and high vulnerability categories, respectively. Additionally, the cities of Abdanan, Murmur, and Sarab Bagh, along with 40 villages, were classified as having very high vulnerability, while 16 villages were designated as being in the high vulnerability zone. These results highlighted the considerable seismic risk faced by the region. Given the potential for earthquakes to cause devastating financial and human losses, it is crucial for responsible organizations to heed the findings of this study. They should implement appropriate protective measures developed in consultation with experts to mitigate risks and enhance community resilience against seismic events. |