Assessing the vulnerability of urban areas and providing an optimal model to reduce damage against earthquakes (case study of Piranshahr city)

Master thesis in the field of geography and urban planning

Abstract

In general, earthquakes are one of the natural disasters that have destructive effects on human settlements and cause heavy losses of life and money to their residents. At the same time, the vulnerability of the city has a direct effect on the human casualties caused by the crisis, and the vulnerability caused by the earthquake is basically the result of the indiscriminate constructions in the boundaries of the faults, the non-compliance with the rules and standards, the inappropriate distribution of the population and facilities in the city, and it is aggravated; Based on this, checking the vulnerability of the city is considered one of the necessities of urban management. Now, considering this importance, in the present study, the vulnerability level of Piranshahr city has been evaluated. In this research, the research method is descriptive-analytical. For this purpose, in the first place, the general vulnerability of Piranshahr city has been investigated by using the relevant indicators and criteria and by using the network analysis model (ANP) and geographic information system (GIS). In the second stage, the vulnerability of the city was determined by using Hierarchical Analysis (AHP), TOPSIS, and VIKOR techniques. Finally, the spatial analysis and location of relief centers, including hospitals, fire stations, and temporary accommodation bases, were done using Nearest Neighbor, Network Analysis Model, ANP, and fuzzy logic (FUZZY) models. The results of the research show that 27% of the city's area has high and very high vulnerability, 56% has moderate vulnerability and 17% has low vulnerability. Also, neighborhoods 21, 23, 31, and 41, which are located in the worn-out (old) city and outskirts of the city, are more vulnerable than other neighborhoods in the city due to their old age, poor quality materials, fine-grained parts, inappropriate proximity of uses, and inappropriate access to hospitals, medical centers, emergency rooms, and fire departments; At the same time, the location of worn-out fabric (Imam Khomeini Street) on the edge of the mountain and non-compliance with standards in construction and structures have increased the level of this vulnerability. In the north and northeast parts of the city, where mostly the buildings are newly built and high quality construction materials have been used, also due to the presence of open spaces and newly built educational and administrative centers and the large area of ??the plots; The possibility of vulnerability in this part of the city is very low.

Key words: urban vulnerability, earthquake, Piranshahr, geographic information system

Introduction

According to population growth and increasing urbanization, the occurrence of natural disasters such as earthquakes can cause heavy losses and casualties and interrupt the development of cities and the country. The need to reduce the vulnerability of cities against this phenomenon is considered as one of the main goals of urban planning and physical planning. In this regard, the first step is to identify the degree of vulnerability of urban components and elements and analyze and evaluate it using existing models in this field to identify vulnerable urban areas and tissues and by specifying these areas to provide scientific and practical solutions in relation to reducing the effects of earthquakes.

The aforementioned issues It raises the need to change the scale of attitude towards the issue of earthquakes from buildings to urban areas. In order to implement this change of attitude, urban planning can be used as one of the main factors in dealing with the adverse effects of earthquakes, and at different levels of urban planning, it is possible to examine and provide practical solutions to reduce the effects of earthquakes at the level of cities. This research aims to take a step towards reducing seismic vulnerability in Piranshahr city by identifying and formulating relationships between urban planning and earthquake crisis management. For this purpose, several sub-topics include: identifying and selecting vulnerability assessment indicators, analyzing the impact of each of the indicators and determining high-risk and dense residential areas and scoring different vulnerability ranges as research options, producing a map of the city's vulnerability to earthquakes, locating temporary accommodation, hospitals and fire stations using fuzzy models and [1] ANP and [2] AHP and using geographic information systems [3] (GIS) and presenting strategies and policies It deals with crisis management in the scope of studies to reduce damages and losses caused by earthquakes in 5 chapters.

[1] -Atrial natriuretic peptide

[2] -Analytical Hierarchy process

[3] - Geographical Information System

1-1- Statement of the problem

One of the issues that most cities in the world are dealing with is natural disasters. A crisis is a sudden event or incident that is associated with widespread human and material damages or the causes of such damages, and requires immediate actions. Such natural events that lead to a critical situation in society are at least potentially dangerous, destructive and deadly (Alexander, 2002: 38).  Earthquake is one of these crises that shakes a part of the earth from time to time and imposes a lot of life and financial losses on people.

The danger of earthquakes covers many countries in the world and is the cause of life failures and most deaths (Smith, 2012: 199). As Iran is located on the Alpine-Himalayan earthquake belt, this country has experienced 130 earthquakes with a magnitude of 5.7 on the Richter scale during the past centuries (Ghafory-Ashtiany, 1999: 4).  According to the United Nations report, in 2003, Iran ranked first among countries in the world in the number of earthquakes with an intensity greater than 5.5 on the Richter scale and one of the highest ranks in terms of vulnerability to earthquakes and the number of people killed as a result of this accident (UNDP, 2004:12). The existence of seismic areas due to the geological location, the existence of many faults in the heart and outskirts of the cities and so on. Along with many human factors such as the urban population, the increase in low-durable urban housing, inappropriate urban planning with the earthquake crisis, all of them have increased the seismic capacity of cities. To the extent that 90% of our country's cities have become vulnerable to a 5.5 magnitude earthquake (Akashe, 1383: 495). Today, the vulnerability of cities to earthquakes is a global issue faced by experts in various fields. This situation has become more acute in countries with risky natural structures, including Iran, during recent decades (Habib, 1371: 13). What turns earthquakes into accidents is the lack of human awareness and the ability to face and deal with it. This issue is generally aggravated by the most extensive unmeasured human interventions in the natural environment, including indiscriminate constructions in fault zones, lack of or disregard for construction rules and standards (Hataminejad et al., 1388: 1).

Undoubtedly, one of the effective factors in reducing the vulnerability of cities, especially damages caused by earthquakes, is the shape and structure that the city has, and it can be done using principled urban planning and design and the attention of crisis management. Reducing the vulnerability of the city took an effective step (Habibi, 2017: 36-27). Therefore, reducing the vulnerability of cities will be realized when the safety of the city against earthquakes is considered as a goal at all levels of city planning. Improper placement of physical elements and uses of urban land, inefficient urban communication network, city infrastructure facilities and uneven distribution of urban open spaces, high age and low quality of buildings in city contexts and such things play a major role in increasing the amount of damage to cities against earthquakes, the increase of unstable buildings and houses is generally in dilapidated contexts due to physical, functional, socio-economic and The environment has an unfavorable condition and is unsafe and vulnerable to natural hazards, especially earthquakes. Although the vulnerability of the city is mainly caused by the instability of the buildings, the impenetrability of some urban structures (due to the inappropriate access of vehicles) and the compactness of the structures, which is caused by the smallness and the abundance of small parts, have intensified the low safety of these structures, especially with the occurrence of accidents. The mentioned cases are all among the categories that, due to their non-observance in the cities, have made the city vulnerable to earthquakes. Therefore, by correcting the situation of urban development in the framework of crisis management, it is possible to reduce the vulnerability of cities against earthquakes and facilitate relief. The city of Piranshahr faces a high risk of earthquake due to the existence of a fault of the same name and with a length of approximately 200 km, which has caused numerous earthquakes, as well as the extent of the city on the mountain slopes where most of the worn-out fabric of the city is located, and inappropriate constructions. Therefore, proper study and identifying vulnerable or safe routes and areas of the city according to specific criteria will reduce the damage caused by the earthquake crisis and provide the possibility of proper planning. This requires a comprehensive study to reduce the effects of the earthquake crisis.