Earthquake Risk and Vulnerability Assessment Based on Wisner and Fuzzy Analytical Hierarchy Process Models in Port Cities: Case Study of Nowshahr City, Iran

Nowshahr port city can suffer a lot of damages in case of an earthquake due to its location in seismotectonics of Alborz with high seismic hazard, proximity to the sea, and expansion on isolated sediments. Therefore, the recognition and analysis of the extent of earthquake vulnerability in different areas of this port city can reduce damages and losses. This study was conducted to analyze and evaluate the earthquake risk and vulnerability and identify safe areas in the city of Nowshahr in times of earthquake.

In this study, the earthquake risk of Nowshahr city was analyzed based on the Wisner model and the application of multi-criteria decision making (MCDM) approach using fuzzy analytic hierarchy process (FAHP). Initially, the effective criteria, sub-criteria, and indicators in the earthquake risk and vulnerability components were collected through a systematic review based on previous research, field survey, and expertschr('39') opinion, and were then screened and weighed by the Delphi method. Finally, the earthquake risk and vulnerability maps were extracted and drawn using a weighted linear combination method and fuzzy index maps related to each component.

According to the findings, about 97.13% (2,810.229 ha), 2.75% (79.567 ha), and 0.12% (3.441 ha) of Nowshahr city were placed in the low, medium, and high-risk category.

Analysis of risk maps showed that the earthquake risk was higher in the central and northwestern parts of Nowshahr city than in the other areas. These areas were densely populated with heavy traffic jams, in which located high-risk facilities, such as gas lines and water and sewer networks, that reminded of the necessity of planning and urgent action regarding the improvement of urban settlements and organization of urban spaces in this region.