The mechanism of tsunami generation due to sector collapse modeled with solid and semi-oval objects, beads, and sands was studies by hydraulic experiments. The profiles of mass flow due to the sector collapse flow with several conditions are designed. The thickness, velocity, and apparent density at the point where the mass plunged into the water surface were measured by laser displacement meters on the slope. Wave height and period of tsunami were measured by four wave gages. As a result, we found the two types of the tsunami generation influenced by the apparent density in case of beads and sands. When the density is high, the objects go deep along the slope. When the density is low, the objects stop near plunging point, and generate tsunami like a wave making plate.
