Model of Tsunami Generation by Collapse of Volcanic Eruption: The 1741 Oshima-Oshima Tsunami

Tsunamis generated by landslides are less studied than those caused by fault motion because of the low frequency of such events and the complexity of the generating mechanism. We carried out hydraulic experiments that simulated a debris flow rushing into water. Using parameters obtained from those experiments, we revised a numerical two-layer model to take into account three kinds of shear stress—bottom friction, horizontal viscosity, and interactive force—and the form drag of the debris flow. We then compared our model results with those from the hydraulic experiments. Then, the improved two-layer model was applied to the 1741 Oshima-Oshima tsunami to reproduce the tsunami height along the Hokkaido coast and the Korean Peninsula in the Japan Sea.