If you mean the latest one which was on December 26, 2004,it happened off the western coast of Sumatra, Indonesia. It was the fifth largest earthquake in recorded history and generated massive tsunamis, which caused widespread devastation when they hit land, leaving an estimated 230,000 people dead in countries around the Indian Ocean including South and Southeast Asia, including parts of Indonesia, Sri Lanka, India, and Thailand.
http://en.wikipedia.org/wiki/2004_Indian_Ocean _earthquake