It was an undersea earthquake caused by subduction and triggered a series of devastating tsunami along the coasts of most landmasses bordering the Indian Ocean.
Where the most damage was caused and why?
The great earthquake of December 26, 2004 was extremely damaging and resulted in many deaths. However most of the destruction and deaths were caused by the catastrophic tsunami waves it generated. Massive tsunami waves wiped out entire coastal areas across southeastern Asia, Sri Lanka, India, Thailand, Myanmar and the islands in the Andaman Sea and the Maldives in the Indian Ocean.
How the shape of beaches affected the amplitude of the wave?
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 water can no longer handle the volume of water, the wave will rise up on top of the sand in the shallower water and break. If the land form creates a gentle slope then the tsunami will appear as 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.
Whether scientists detected the earthquake in time to warn people about it?
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 systems 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.
Why most people did not get a warning??
One of the few coastal areas to evacuate ahead of the tsunami was on the Indonesian island of Simeule, very close to the epicenter. Island folklore recounted an earthquake and tsunami in 1907, and the islanders fled to inland hills after the initial shaking yet before the tsunami struck. On Maikhao beach in northern Phuket, Thailand, a 10-year-old British tourist named Tilly Smith had studied tsunami in geography class at school and recognized the warning signs of the receding ocean and frothing bubbles. She and her parents warned others on the beach, which was evacuated safely. John Chroston, a biology teacher from Scotland, also recognized the signs at Kamala Bay north of Phuket, taking a busload of vacationers and locals to safety on higher ground.
What can be done to reduce the loss of life and damage if another tsunami occurs in the same area??
Have people warned so the can escape the tsunami in time.
Build seawalls so you can reduce the wave from being very strong.
Reduce the number of buildings near the sea so the damage is reduced.
Reduce the population living I seaside areas to reduce the deaths.