Landslide tsunami case studies using a Boussinesq model and a fully nonlinear tsunami generation model

Abstract

Abstract. Case studies of landslide tsunamis require integration of marine geology data and interpretations into numerical simulations of tsunami attack. Many landslide tsunami generation and propagation models have been proposed in recent time, further motivated by the 1998 Papua New Guinea event. However, few of these models have proven capable of integrating the best available marine geology data and interpretations into successful case studies that reproduce all available tsunami observations and records. We show that nonlinear and dispersive tsunami propagation models may be necessary for many landslide tsunami case studies. GEOWAVE is a comprehensive tsunami simulation model formed in part by combining the Tsunami Open and Progressive Initial Conditions System (TOPICS) with the fully nonlinear Boussinesq water wave model FUNWAVE. TOPICS uses curve fits of numerical results from a fully nonlinear potential flow model to provide approximate landslide tsunami sources for tsunami propagation models, based on marine geology data and interpretations. In this work, we validate GE-OWAVE with successful case studies of the 1946 Unimak, Alaska, the 1994 Skagway, Alaska, and the 1998 Papua New Guinea events. GEOWAVE simulates accurate runup and inundation at the same time, with no additional user interference or effort, using a slot technique. Wave breaking, if it occurs during shoaling or runup, is also accounted for with a dissipative breaking model acting on the wave front. The success of our case studies depends on the combination of accurate tsunami sources and an advanced tsunami propagation and inundation model.

Submarine landslides at the eastern Sunda margin: observations and tsunami impact assessment

“…Following Watts et al (2003), an initial wave distribution can be used to approximate the sea surface deformation provoked by the mass movement. It is argued that during the acceleration phase of a slide, most of the tsunami energy is invested in potential energy.…”

“…Here, we want to concisely summarize their approach and the formulas we applied in this publication. For the complete line of argumentation involved in this formulation, we refer to the original publications (Watts et al 2003;Grilli and Watts 2005;Watts et al 2005). …”

Submarine landslides in the Santa Barbara Channel as potential tsunami sources

“…This is the only time at which Geowave can transfer the surface elevation from TOPICS to FUNWAVE, and this time is fixed by landslide dynamics that are specific to each event. Geowave has been extensively validated through tsunami case studies (e.g., Watts et al, 2003). Geowave has almost always reproduced tsunami observations the first time a simulation is performed, and it has usually reproduced all tsunami observations.…”

“…Using typical values found from similar model runs, we adopt the following reasonable values: ρ b =1900, ρ o =1025, C m =1.17, and C d =1.44. We follow Watts and Grilli (2003) and further assume 1), that landslide deformation increases center of mass acceleration by 40%, 2), that landslide length increases by 35% of the distance traveled by the center of mass, and 3), that the landslide nose increases its distance from the center of mass by 16% of the distance traveled by the center of mass. These assumptions allow us to reproduce the elongation and final deposit thickness of each landslide.…”

The hydrodynamics of landslide tsunamis: current analytical models and future research directions

“…In an attempt of simplifying such complex dynamics, Watts et al (2003) initially neglected the direct bottom forcing and assigned a hot-start condition at the free surface from SMF tsunami generation. Such an initial condition was then to be implemented in tsunami propagation and inundation models.…”