Many people acted heroically in the aftermath of Hurricane Katrina. The Coast Guard, for instance, rescued some 34,000 people in New Orleans alone, and many ordinary citizens commandeered boats, offered food and shelter, and did whatever else they could to help their neighbors.
Tidal waves, or tides, are a predictable, com-mon occurrence along coastal communities, generated by forces beyond Earthâthe gravitational pull of the sun and moon. However, tsunamis are not predictable. They are often generated by earth-quakes, volcanic activity, and slope failure.idal waves, or tides, are a predictable, com-mon occurrence along coastal communities, generated by forces beyond Earthâthe gravitational pull of the sun and moon. However, tsunamis are not predictable. They are often generated by earth-quakes, volcanic activity, and slope failure.
The resulting waves can be extremely dangerous and devastating to low-lying coastal areas as they enter shallow water and hit the shoreline. A tsunami can occur at any state of the tide and even at low tide it will inundate coastal areas if the incoming waves surge high enough. Tsunamis may occur in large lakes. About 86% of all tsunamis result from so-called sea-quakes.