Physical Modeling of Landslide Tsunamis – a Novel Generator

Landslides may pose perceptible tsunami hazards to areas commonly regarded as immune. A large number of historic and prehistoric slope failures have been reported covering a broad range of landslide volumes and resulting tsunamis. Landslide generated tsunamis were investigated in a two-dimensional physical laboratory model based on the generalized Froude similarity. The slide impact characteristics were controlled by means of a novel pneumatic landslide generator. State-of-the-art laser measurement techniques such as digital particle image velocimetry (PIV) were applied to the decisive initial phase. The wave generation was characterized by an extremely unsteady three phase flow. PIV provided instantaneous velocity vector fields in a large area of interest and gave insight into the kinematics of the wave generation process. The main wave characteristics were related to the landslide parameters driving the whole wave generation process. The physical model results were compared to the giant rockslide generated tsunami which struck the shores of the Lituya Bay, Alaska, in 1958. Further the experimental results were used as a benchmark for numerical flow simulations. A full Navier-Stokes Eulerian compressible hydrodynamic (SAGE) has been applied by Dr. Charles Mader (LANL). A novel pneumatic landslide apparatus enables the generation of three dimensional landslide tsunamis as well as direct control of the coupling between landslide motion and tsunami generation. The most advanced landslide tsunami generator will run a first experimental series in the NEES-tsunami wave basin at OSU in the summer of 2006. Acknowledgement: The presented research work from a decade of landslide tsunami experimentswas supported by the National Science Foundations (NSF) in the USA (2004-2007) and Switzerland(1997-2002). The author is a recipient of an Individual Investigator NEESR-award. ReferencesFritz, H.M. (2006). Physical modeling of landslide generated tsunami. In: A. Mercado-Irizarry and P.L.-F. Liu (eds) Caribbean Tsunami Hazard. World Scientific, Singapore, 308-324.Fritz, H.M., Hager, W.H., Minor, H.-E. (2004). Near field characteristics of landslide generated impulsewaves. J. Waterway, Port, Coastal, and Ocean Engrg., ASCE, 130:287-302.Fritz, H.M., Hager, W.H., Minor, H.-E. (2003a). Landslide generated impulse waves: part 1:instantaneous flow fields. Exp. Fluids 35:505-519.Fritz, H.M., Hager, W.H., Minor, H.-E. (2003b). Landslide generated impulse waves: part 2:hydrodynamic impact craters. Exp. Fluids 35:520-532.Fritz, H.M., Moser, P. (2003). Pneumatic landslide generator. Int. J. Fluid Power 4(1):49-57.Fritz, H.M. (2002). PIV applied to landslide generated impulse waves. In: R.J. Adrian et al. (eds) Lasertechniques for fluid mechanics. Springer, New York, 305-320.Fritz, H.M., Hager, W.H., Minor, H.-E. (2001). Lituya Bay case: rockslide impact and wave run-up.Science of Tsunami Hazards 19(1):3-22.