2. The earthquake was caused by subduction and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean.
3. The wave generated by a tsunami is really a large swell. Swells continue along until they meet the resistance of shallowing water. When the depth of the water can no longer handle the volume of water, the wave will rise up on top of the sand in shallower water and break. If the land form creates a gentle slope then the tsunami will appear as a very strong tidal flow. If the shore is steep then the swell will rise up and break against the beach. Most damage is not done by a large crashing wave, but by the sheer volume of water that is flowing onto the land and carrying debris along with it .
4. Despite a lag of up to several hours between the earthquake and the impact of the tsunami, nearly all of the victims were taken completely by surprise. There were NO Tsunami Warning system in the Indian Ocean to detect tsunamis or to warn the general populace living around the ocean. Tsunami detection is not easy because while a tsunami is in deep water it has little height and a network of sensors is needed to detect it. Setting up the communications infrastructure to issue timely warnings is an even bigger problem, particularly in a relatively poor part of the world.
