Tsunami Modeling in the South American Subduction Zone Inferred from Seismic Coupling and Historical Seismicity

Throughout its history, South America has experienced megathrust earthquakes which have produced large tsunamis, devastating coastal cities in the near and far field. Studying these phenomena is important for tsunami hazard mitigation in this region. We propose 10 earthquake scenarios along the South American subduction zone on the basis of the seismic history of each region, seismic-geodetic coupling, general scaling relationships, among others. Tsunami run-up (coastal amplification) is then estimated using 200 nonuniform stochastic sources for each scenario, totaling 2000 simulations. Our results show great variability in run-up distribution along the Nazca-South America subduction zone, with some of the most affected areas being Valparaiso in Chile, with a most likely scenario of 20 m of run-up and a maximum scenario of 33 m; and Lima in Peru, with 25 and 40 m for the most likely and maximum scenarios, respectively. Similar results are seen in Iquique and Huasco in Chile. We have also identified 17 coastal locations with a higher vulnerability due to local amplification of tsunami run-up and two instances in which a regional amplification can occur due to tsunami directivity and coastal barriers. We conclude that tsunami hazard remains high along the coast of South America, even in areas where great earthquakes have recently occurred.