Why didn't anybody know about the boxing day tsunami 2004?

Answer 1

Some people did; they recognized the signs of an incipient tsunami.

A tsunami is caused by an undersea earthquake that causes a landslide deep in the ocean. The water displaced by the landslide is propelled an hundreds of miles per hour across the oceans until it reaches the shore.

The first sign of a tsunami is that the water RECEDES; the ocean pulls way out from the shore, and only a couple of minutes later does the water flow back in in force. In Malaysia, a British family was on the beach and the 12-year-old daughter saw the sea pull away from the shore. She had read about tsunamis in school the year before, and recognized what was happening. She alerted her family and the people around them on the beach, and they all fled to higher ground and survived. In the Andaman Islands, an entire village fled to the mountains because their ancient traditions demanded that if the sea were ever to recede, the villagers should immediately gather at their mountain temple.

Many others followed the water away from the shore, and were swept out to sea.

The problem is that so far, scientists have not developed an accurate way to predict earthquakes. So earthquakes always are a surprise when they happen, even when (as here in California) everybody expects an earthquake "someday soon". Nations around the Pacific have developed a tsunami warning system designed to detect the surge of water that is the tsunami while it is still far out to sea, and to radio alerting messages to land. However, the warning buoys are expensive to deploy and require considerable maintenance, so they have not (so far) been especially effective.

Answer 2

you can't prevent a Tsunami because it's a big waves so you will die