Wavenumber-frequency analysis of landslide-generated tsunamis at a conical island. Part II: EOF and modal analysis

In this paper the Empirical Orthogonal Function (EOF) method is applied to extract from the experimental data, related to landslide-tsunamis around the coast of a conical island, the spatial modes that contribute to the wave field. For each mode the wavenumber and the frequency are calculated by analyzing the shape along the coast and the time function. The relevant modes are then compared with those obtained through numerical eigenanalysis of the long wave equation around the considered island. It was possible to associate each EOF mode with some eigenvectors and the corresponding eigenfrequencies, both on the basis of the spatial shape, the wavenumber calculated along the coast and the frequency. Results confirm that landslide-generated waves propagate along the coast as trapped edge waves and the zero-th order mode is the most important. Further of exploring the physics, it is believed that this paper can be of use as some of the most relevant and straightforward techniques for modal identification are applied to the same problem and dataset.