Numerical Simulation of Submarine Landslide Tsunami Due to 1946 Aleutian Tsunami Earthquake

The 1946 Aleutian Earthquake is one of the most famous tsunami earthquakes. This earthquake, which occurred off the coast of Unimak Island, generated a huge near-field tsunami that could not be explained by the tsunami generated by the fault movement. Submarine landslide is believed to be the second source. The realistic submarine landslide-generated tsunami with the earthquake source model is determined in this paper. Submarine landslide-tsunami simulation was conducted in two phases. In the first phase, both tsunami and submarine landslide were numerically computed. Tsunami Squares method previously developed were improved for deep submarine landslide and applied. In the second phase, tsunami propagation and run-up were computed with the finite differential method. Calculation results well explained the survey data in the near field. At Scotch Cap lighthouse, which was destroyed in this event, the computed tsunami height was 23.9 m, enough height to destroy the lighthouse. Results show the compact pattern of tsunami run-up height distribution which was expected from the previous study. The improved landslide-generated tsunami computation method well reproduced the characteristic of submarine landslide tsunami.