TSUNAMI INUNDATION MODELING AND HAZARD MAPPING OF THE SOUTH COAST OF ECUADOR
Supervisor: Shunichi KOSHIMURA
The subduction between the Nazca oceanic plate and the Andean Continental plate describes the tectonics and seismicity around Ecuador generating great earthquakes over Mw 7.5 with return periods of 100-250 years. Historically, great earthquakes and tsunamis occurred in 1906, 1942, 1958, 1979 (north cost of Ecuador) and 1901, 1933, 1953 and 1959 (south coast of Ecuador). The study area is located in a subduction zone in the southern part of the coast of Ecuador where a seismic gap has been present since 1901. Here, most of the historical events have not been well documented and the information about the impact to the coast is limited or none. The objective of this study is to estimate the tsunami impact from potential local seismic sources in the south coast of Ecuador (offshore Salinas) proposing several scenarios to conduct a tsunami hazard assessment. The scenario simulation was conducted using TUNAMI-N2 code developed by the Disaster Control Research Center (DCRC), Tohoku University, Japan; this code is based on nested grids systems (Cartesian coordinates) in four (4) domains. The seismic source scenario was an earthquake with magnitude Mw 8.0. The results, which were evaluated based on tsunami height and inundation depth maximum values, led to two scenarios of the southwest of Salinas where the impacts would be significant. We estimated the maximum height exceeding 7.0 meters and extent of inundation over 80% (6.49 inundation depth) of the study area, and also tsunami arrival times as less as 16 minutes. These results, however, are not validated with any historical data because most of the events generated on the south coast of Ecuador are not well documented. The design of the resulting map should be adjusted to the local needs to improve the outreach of information to people in Salinas. Tsunami numerical simulation and hazard mapping are tools that can be used to mitigate the impact of tsunamis in Salinas and surroundings.