Quick facts:
A tsunami can reach speeds in excess of 600MPH (jet plane).
The speed will diminish as it reaches deeper or more shallow water.
As the wave reaches shallow water it will rise from the ocean and generally it's between 50 and 100 feet high before it hits dry land.
Such waves generally have a 1,000 feet reach inland.
The largest recorded wave was 1,722 feet which hit Lituya Bay Alaska in 1958. This is due to the nearness of the land to the epicentre of the underwater earthquake. Lituya Bay was virtually wiped off the face of the Earth.