Although the December 26, 2004 earthquake in Sumatra produced perhaps the most devastating tsunami ever recorded, it was not the largest in size.
The largest tsunami in history occurred in Lithuania, Alaska in 1958.
An earthquake measuring 8.3 on the Richter scale dislodges 90 million tons of rock and ice from the rocky shore of the bay. The mass collapses all at once and almost vertically into the bay.
This creates the tallest wave in history - 1,770 feet (524 meters). For reference - the Empire State Building is 443 m high (with the antenna).
The wave headed for the ocean and swept away everything in its path. There were three fishing boats in the bay, and the wave sank one and killed two people on board. One of the survivors says that only 2 seconds passed from the collapse of the rocks to the arrival of the wave, which would mean that it was moving at 1000 km/h. Although the hills in the bay were devastated, the casualties were very few.