Triggereing of radiating landslide Tsunami modes around conical islands

Volcanic islands are prone to massive landslides and flank collapses, which can trigger tsunamis with devastating consequences. A notable example is the 2018 Anak Krakatau tsunami, which resulted in the loss of over 400 lives. While some of the energy from such landslides generates far-field tsunamis that propagate over large distances, a significant portion creates trapped waves that travel around the island. These trapped waves, unaffected by geometric spreading, can reach distant coastal areas on the same island, potentially causing severe localized damage.

Although numerous numerical studies have explored landslide-generated tsunamis in the context of conical islands, analytical studies that delve into the underlying physics of the phenomenon remain limited. Recent research in fluid mechanics has yet to analytically determine the discrete frequencies of trapped and radiating waves. Accurate calculation of the discrete frequency spectrum of trapped wavefields is crucial for assessing coastal hazards. In this study, we present a comprehensive analytical solution for the radiating and trapped wavefields generated by landslide sources with varying time histories on conical island flanks.