Compilation and validation of indicators for assessing the vulnerability of urban peripherals to earthquake (case study: rural settlements in the Tehran metropolitan area)

Due to the increase in population and the increase in the interaction between humans and the natural environment, humans are more exposed to the risk of natural disasters. Despite all the progress made in recent decades, the negative effects of natural disasters are still felt, and mankind has not been able to significantly reduce the damage caused by natural hazards. Earthquake is one of the natural hazards that cannot be predicted and causes many damages every year. Iran is considered one of the most earthquake-prone countries in the world and has historically witnessed many severe earthquakes. In this context, the Tehran metropolitan area is one of the areas with a high risk of earthquakes in Iran, which, in addition to the risk of earthquakes due to the high population density, has a high potential for vulnerability to earthquakes. So far, several studies have been conducted in connection with the vulnerability of urban spaces located in the Tehran metropolitan area, but the vulnerability of rural spaces located in the Tehran metropolitan area has not received much attention from researchers. The first step to analyzing natural disasters and assessing vulnerability to hazards is to identify and determine appropriate indicators. Since in the studies carried out so far, the identification of earthquake vulnerability assessment indicators according to the specific characteristics of peri-urban spaces has not been done, the purpose of this study is to compile and validate appropriate indicators for assessing the vulnerability of rural settlements located in the Tehran metropolitan area.

This study is applied research, and it is descriptive-analytical in terms of method. The research approach is a mixed method (qualitative-quantitative). The qualitative part of the research has been done by using a systematic review of research sources and checking the content of similar articles. From this point of view, the indicators for assessing the vulnerability of rural settlements against earthquakes have been identified. After that, the appropriateness of each index was determined using the Delphi method and the opinions of experts. In the quantitative part of the research, using descriptive and inferential statistics such as mean, standard deviation, coefficient of variation, and One-sample t-test, indicators have been refined and validated. The statistical population of this research included all the experts and people specializing in the field of vulnerability to environmental hazards, of whom 40 experts were selected as a sample by using the purposeful sampling method.

In this study, 38 scientific articles related to the research topic have been identified by using a systematic review of sources to identify indicators of vulnerability to earthquakes, and 98 indicators have been identified by examining their content in the first step. This number has reached 41 indicators after performing initial refinement, removing irrelevant items, and merging similar items. These indicators, categorized in the form of three components that make up the concept of vulnerability, include exposure, susceptibility, and resilience. For validation, the indicators have been provided to the experts through the design of a questionnaire. The analysis of the results from the collection of questionnaires reveals that the component of being exposed to risk has three indicators. Each of the three indicators has been considered appropriate by experts in terms of the average, standard deviation, coefficient of variation, t-statistic value, and significance level. The susceptibility component has 17 indicators, two of which are in poor condition in terms of mean, standard deviation, coefficient of variation, t-statistic value, and significance level, and 15 other indicators are in good condition and have been approved by experts. The resilience component has 21 indicators, two of which are in poor condition in terms of mean, standard deviation, coefficient of variation, t-statistic value, and significance level, and 19 other indicators are in good condition and have been approved by experts. Finally, among the identified indicators, 37 of them were approved as suitable indicators for assessing the vulnerability of peri-urban rural settlements against earthquakes.

The findings of the study demonstrate that the values obtained for the indicators of risk exposure are at a more suitable level than the indicators of the other two components, confirming the expert consensus and agreement about the indicators of risk exposure. After that, there are the susceptibility component and the resilience component in terms of the experts' agreement. The results of this research, in terms of scientific application, provide a suitable platform for researchers in the fields of geographic sciences, environmental sciences, social sciences, disaster sciences, and other related specialized fields, each of which in some way studies the concept of vulnerability to earthquake hazards.