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Tsunami Generation and Runup Due to Three-dimensional Landslide

Large-scale experiments have been conducted in a wave tank with a 104 m-long, 3.7 m-wide, and 4.6 m-deep wave channel with a plane slope (1:2) located at one end of the tank; part of the experimental setup is shown in Fig. 1. A solid wedge was used to model the landslide. The triangular face had a horizontal length of $b$ = 91 cm, a vertical face with a height of $a$ = 45.5 cm, and a width of $w$ = 61 cm (Fig. 2). The horizontal surface of the wedge was initially positioned either a small distance above or below the still water level to reproduce a subaerial or submarine landslide. The block was released from rest, abruptly moving downslope under gravity, rolling on specially designed wheels (with low friction bearings) riding on aluminum strips with shallow grooves inset into the slope. The wedge was instrumented with an accelerometer to accurately define the acceleration-time history and a position indicator to independently determine the velocity and position time histories. Wedge positions are given in Fig. 3 for the two cases presented here.

Figure 1: Picture of part of the experimental setup.
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A sufficient number of wave gages were used to determine the seaward propagating waves, the waves propagating to either side of the wedge, and for the submerged case, the water surface-time history over the wedge. In addition, the time history of the runup on the slope was accurately measured. Time histories of the surface elevations and runup measurements for two cases are presented in Figs. 4 and 5 for the submerged cases with $\Delta = -0.025$ m and $\Delta = -0.1$ m, respectively. While a total of more than 50 experiments with moving wedges, hemispheres, and rectangles were conducted (Liu et al., 2005), the wedge experiments were used as benchmark tests in the 2004 Catalina Island, Los Angeles, California workshop (Liu et al., 2008). Details and more experimental results can be found in Liu et al. (2005).

Figure 2: Schematic of the experimental setup. Gage locations where time histories of the surface elevation and runup measurements are provided: gage 1 at $(x, y) = (1.83, 0)$, gage 2 at $(x, y) = (1.2446, 0.635)$, runup gage 2 at $(x, y) = (0, 0.305)$, and runup gage 3 at $(x, y) = (0, 0.61)$. While $x$-axes follows center cross section pointing seaward $y$-axes follows the initial shoreline starting from center cross section.
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Figure 3: Time histories of the block motion for the submerged case with $\Delta = -0.025$ m (data here) and $\Delta = -0.1$ m (data here).
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Figure 4: Time histories of the surface elevation (gage 1 and gage 2) and runup (runup gage 2 and runup gage 3) measurements with respect to still water level for the submerged case with $\Delta = -0.025$ m.
\includegraphics[width=4.5in]{SP3053_figA31_helvetica.eps}

Figure 5: Time histories of the surface elevation (gage 1 and gage 2) and runup (runup gage 2 and runup gage 3) measurements with respect to still water level for the submerged case with $\Delta = -0.1$ m.
\includegraphics[width=4.5in]{SP3053_figA32_helvetica.eps}

References:

Liu, P.L.-F., T.-R. Wu, F. Raichlen, C.E. Synolakis, and J. Borrero (2005): Runup and rundown generated by three-dimensional sliding masses. J. Fluid Mech., 536, 107-144.

Liu, P.L.-F., H. Yeh, and C. Synolakis (2008): Advanced Numerical Models for Simulating Tsunami Waves and Runup. Advances in Coastal and Ocean Engineering, 10, 250 pp.