A bore is a wall of turbulent water that can be several meters high, and can rush onshore with great destructive power. Behind the bore is a deep and fast-moving flood that can pick up and sweep away almost anything in its path, such as what happened in Papua New Guinea in 1998 when more than 2,000 people were killed and villages destroyed. Minutes later, the water will drain away as the trough of the tsunami wave arrives, sometimes exposing great patches of the sea floor. But then the water will rush in again as before, causing additional damage. This destructive cycle may repeat many times before the hazard finally passes.
Persons caught in the path of a tsunami have little chance to survive.
They can be easily crushed by debris or they may simply drown. Children and the elderly are particularly at risk, as they have less mobility, strength, and endurance. Tsunamis typically cause the most severe damage and casualties very near their source. There the waves are highest because they have not yet lost too much energy to friction or spreading. In addition, the nearby coastal population, often disoriented from the violent earthquake shaking, has little time to react before the tsunami arrives.