Population and infrastructure vulnerability study under a tsunami scenario in the city of Manta-Ecuador

Abstract

Ecuador is a country with frequent seismic and tsunamigenic events due to its close location to a subduction zone between the plates of Nazca and South America. The main objective of this study was to assess the vulnerability of the population and infrastructure of the city of Manta-Ecuador towards a tsunami event. To evaluate the infrastructures, fragility and vulnerability index functions were used, while only fragility functions were considered for the population. Manta has a population of 249,868 permanent inhabitants. The most severe tsunami scenario impacting inhabitants and buildings was selected considering historical data, mathematical modeling, characteristics of infrastructure and population. To perform the simulation, a hypocenter was proposed: 40 km northwest of Manta, 3 km oceanic depth and magnitude moment 8. The simulation results showed floods in 6% of the total area of the city. The analysis conducted by fragility functions indicated that from 2,040 exposed people, 468 would be affected, in particular minors, elderly and disabled groups, not accounting tourists. Also, 221 structures would be affected from 843 exposed in the flooded zones with a maximum flood depth higher than 5 m representing 26% and 0.2 % of the exposed and total buildings in the city respectively. The results of this study would assist in identifying risky and safe areas, shelter buildings, routes and evacuation times during a tsunamigenic event.