The weight and speed of the Tsunami

The quake of Northern Sumatra set off a tsunami that eventually reached the shores of North and South America.

From what is reported, this wave started at about one metre (3.1 ft) in depth.  Its breadth was nearly 800 miles.  To reach the coast of Africa it had to travel at least 500 miles.

According to the calculations based on James Berkland's article "Water Weight". (See copy on this website or visit: 

Sea water weighs a little under a million tons per square mile (per foot of sea-water).

At three feet deep, 3 million tons per square mile.

800 x 500 = 400,000 square miles (this is just the coast of Africa, it went on diminishing as it went, to the coast of the Americas.)

This means 3,600,000,000,000 tons of water was displaced at 500 miles per hour.

3.5 trillions tons at 500 miles per hour!!

If you are an expert on these things, please correct this.  Otherwise, laymen as we are, we can begin to understand why there may have been an earth wobble created by this one event.