**1. Introduction**

Impulsive waves (i.e. tsunamis) are likely to be generated by earthquakes, landslides, volcanic eruptions, impacts of asteroids and gradients of atmospheric pressure (Løvholt et al. [1]). There are coastal areas which are particularly prone to landslide-generated tsunami risk. The destructive effects caused by the impulsive waves, generated by landslide sources, can be strongly magnified by the characteristics of the so-called "confined geometries" (e.g. bays, reservoirs, lakes, volcanic islands, fjords, etc.). Complicated physical phenomena (e.g. trapping mechanisms, edge waves, wave runup, etc.) take place as a consequence of the interaction between the generated waves and the local bathymetry controlling the tsunami propagation and interaction with the coast. Many past events of landslidegenerated tsunamis testify this reality (e.g. Lake Geneva, Switzerland, *Kremer et al.* [2]; Lituya Bay, Alaska, *Fritz et al.* [3]; Vajont Valley, Italy, *Panizzo et al.* [4]; Stromboli Island, Italy,*Tinti et al.* [5]; Papua New Guinea, *Synolakis et al.* [6]; Anak Krakatau, Indonesia, *Grilli et al.* [7]).

**Figure 1** provides good examples of areas prone to landslide tsunami hazard (upper left panel: Lituya Bay, Alaska; upper right panel: Vajont Valley, Italy; lower panels: Stromboli Island, Italy). The physical process at hand is generally characterized by smaller length and time scales than those of tsunamis generated by

### **Figure 1.**

*Pictures of areas historically affected by landslide-generated tsunamis. (a) Lituya Bay, Alaska, 1958. (b) Vajont Valley, Italy, 1963. (c) Stromboli Island, Italy, 2002. (d) Damages at Stromboli Island, Italy, 2002.*

earthquakes. The triggering mechanism (the landslide), can be classified as subaerial, partially submerged or completely submerged, depending on the initial landslide position [8, 9]. The occurrence of the landslide at the water body boundary implies that the generated impulse waves propagate both seaward and alongshore. Moreover, complicated physical phenomena due to the interaction between the waves and the sea bottom (e.g. trapping mechanisms *Bellotti and Romano* [10], *Romano et al.* [11]) are likely to plays a significant role, which comprehension is essential for designing and implementing the so-called early warning systems *Bellotti et al.* [12], Cecioni et al. [13], De *Girolamo et al.* [14].

The complex physical phenomena related, on one hand, to the landslide triggering mechanisms and, on the other hand, to the tsunami generation, propagation and interaction with the coast mechanisms are brilliantly and exhaustively described by **Figure 1** (and its description) of *Di Risio et al.* [8]. Due to its clarity and usefulness, this figure is here reported (**Figure 2** of the present manuscript). As mentioned, depending on the initial landslide position, as well as on the geometry of the near- and the far-field, the tsunami characteristics can change significantly. Therefore, to reduce and/or to mitigate the landslide-generated tsunami risk the comprehension and the right modeling of such complicated phenomena is essential. Numerous studies dealing with landslide-generated tsunamis are available in the scientific literature. Experimental, analytical, and numerical models have been extensively used (both as separated tools and in conjunction) to shed light on this complicated natural event.

*Physical and Numerical Modeling of Landslide-Generated Tsunamis: A Review DOI: http://dx.doi.org/10.5772/intechopen.93878*

**Figure 2.** *Sketch of landslide-generated impulse waves [8].*

In this chapter a special attention to the experimental and numerical modeling of landslide-generated tsunamis is given. It is important to highlight that this work has not the haughtiness to provide an exhaustive description, since the beginning to the present days, of the physical and numerical modeling techniques related to landslide-generated tsunamis. Indeed, brilliant and exhaustive review of the state of the art, as well as of the future challenges, related to the physical and numerical modeling of landslide-generated tsunamis are provided by authoritative Authors. It is worth to remember, among others, the excellent review of the physical model experiments, together with the main results and achievements, provided *Di Risio et al.* [8], as well as the exhaustive description of the landslide-generated tsunami numerical modeling techniques addressed by *Yavari-Ramshe and Ataie-Ashtiani* [15]. Thus, the objective of the present chapter lies in providing an update of the state of the art related to the physical and numerical modeling techniques of landslide-generated tsunamis, with a special focus on those studies published in the last ten years. Moreover, as far as numerical models are concerned a special attention is paid to the recently developed Computational Fluid Dynamics (CFD) techniques; in fact, the development and the application of these techniques has experienced a boost up the last decade. It is worth noticing that analytical modeling is not considered in the Chapter.

As stated, in this study a review of the physical and numerical modeling techniques related to landslide-generated tsunamis is provided. The main purpose of this study lies in describing, with no claim to be exhaustive and by adopting a flowing style, the main approaches exploited so far and in discussing the potentials as well as the limitation of the methods themselves. Moreover, the future challenges related to the present research field are discussed. This chapter in organized as follows. In the next section a review of the physical modeling techniques related to landslide-generated tsunamis is presented. Then, a section dealing with the numerical modeling techniques follows. Finally, concluding remarks close the chapter.
