Experimental modelling of tsunami generated by underwater landslides
Preliminary results from a set of laboratory experiments aimed at producing a high-quality dataset for modeling underwater landslide-induced tsunami are presented. A unique feature of these experiments is the use of a method to measure water surface profiles continuously in both space and time rather than at discrete points. Water levels are obtained using an optical technique based on laser induced fluorescence, which is shown to be comparable in accuracy and resolution to traditional electrical point wave gauges. The ability to capture the spatial variations of the water surface along with the temporal changes has proven to be a powerful tool with which to study the wave generation process. In the experiments, the landslide density and initial submergence are varied and information of wave heights, lengths, propagation speeds, and shore run-up is measured. The experiments highlight the non-linear interaction between slider kinematics and initial submergence, and the wave field. The ability to resolve water levels spatially and temporally allows wave potential energy time histories to be calculated. Conversion efficiencies range from 1.1%-5.9% for landslide potential energy into wave potential energy. Rates for conversion between landslide kinetic energy and wave potential energy range between 2.8% and 13.8%. The wave trough initially generated above the rear end of the landslide propagates in both upstream and downstream directions. The upstream-travelling trough creates the large initial draw-down at the shore. A wave crest generated by the landslide as it decelerates at the bottom of the slope causes the maximum wave run-up height observed at the shore.