Physical modeling of tsunamis generated by subaerial, partially submerged, and submarine landslides

In the present study, three different types of landslide-generated tsunamis (subaerial, partially submerged and submarine) were investigated through laboratory experiments that used 261 different experimental conditions. The results show that, for the near-field region, the subaerial landslide generated a higher leading wave, while the submarine landslide generated a higher second wave. However, frequency dispersion considerably influenced their propagation, with the leading wave decaying and the trailing waves being enhanced. The present study also revealed that the leading wave has higher values for wave celerity, period, and length than the second wave, regardless of landslide type. It was also shown that the celerity of the leading wave and second wave can be approximated by the solitary wave theory and third-order Stokes theory, respectively. Using the extensive experimental dataset obtained, predictive equations to estimate the maximum crest amplitudes generated by partially submerged and submarine landslides were also developed. A comparison with the experiments of previous researchers and field survey data from the 2018 Palu Tsunami indicated that these equations can estimate reasonably well the height of the generated tsunami. It was also shown that the relative mass and initial position of the landslide are influential nondimensional parameters to determine the tsunami amplitudes generated.