Population and building vulnerability assessment by possible worst-case tsunami scenarios in Salinas, Ecuador

Abstract

Ecuador has been prone to experience earthquakes and tsunamis linked to events in the subduction zone between the Nazca and the South American plates. The main objective of this investigation was to assess the population and buildings vulnerability by a possible worst-case Tsunami scenario in the highly touristic city of Salinas—Ecuador. The vulnerability of buildings was investigated by Fragility Functions (FFs) and Vulnerability Index, while the population vulnerability was assessed by FFs. The population of permanent residents (42,860 inhabitants) and tourists (highly variable, but reaching up to 40,163 tourists/day and 4790 tourists/night) were separately studied during nine public holydays/long weekends (i.e., when the population density reaches critical levels), and during daytime/nighttime. In the selected scenario (i.e., hypocenter: 100 km southwest of Salinas, ocean depth: 2 km, and 8.0 moment magnitude), the flood area covered 43% of Salinas county and 43–85% of urban parishes. The most populated areas were exposed to inundation. According to FFs analysis, between 16,380 and 45,410 people would be affected by a tsunamigenic wave during the day and between 7386 and 10,037 during the night of Christmas and Declaration of Independence holydays, respectively. Elderly, handicapped, underage, and tourist were the most vulnerable groups. A total of 2227 structures would be affected by tsunamigenic wave (FFs), representing 40% of exposed structures to the flood area (i.e., 2.03–6.63 m maximum flood depths). A total of 3160 buildings showed Vulnerability Indexes ranging from medium to high. Results from this study would assist in the identification of hazard areas, safe zones, shelter buildings, evacuation routes/times in this densely populated touristic city.