抄録
Surge waves often form on the free surface of debris flows. These surge waves have the form of a hump that moves down slopes at speeds that are greater than those recorded for the free surface and the front of the debris flows. Surge waves can be very destructive. In the present study, a theoretical analysis is proposed to explain the formation and the velocities developed by these surge waves. The analysis models the debris flow material as one having a frictional-viscous resistance to flowing down slopes. Using this model, it was determined that surge waves travel on the free surface of debris flows at a speed that is two times greater than that recorded for the free surface and three times greater than the mean velocity of the debris flow. The theoretical findings were substantiated by velocity measurements on a debris flow in Sakurajima, Japan.
