Water weighs roughly 1,700 pounds per cubic yard. With a power such as this, water can easily demolish any structure not built to withstand this amount of force. Imagine a surge the size of a hurricane (roughly 50 miles) and the amount of devastation it might cause. Most of the damage caused in a hurricane is due to the storm surge because the water rushes with tremendous force at the base of a structure, making it collapse. Nine out of ten hurricane fatalities are caused by the storm surge. Dunes are built on the mouths of beaches to prevent surges. They act as a wall to hold the water so it cannot pass into residential areas and cause damage. Sometimes, however, the dunes prove to be useless.