You can consider the following point for writing your essay;
In the Indian Ocean, an earthquake occurred in the year 2004. The epicenter of the quake was in Indonesia. However, it resulted in the tsunami, which devastated and killed more than two thirty thousand people. A tsunami is the aftermath of a strong earthquake in sea or ocean.
We have seen many calamities and tsunami in past as well has caused many devastation. It causes damage by either smashing with water along the coastal area or by draining the land.