In the movie :
Ultimately, after a last-ditch effort to use all of Earth's missile-borne nuclear weapons to destroy the comets fails, "Beiderman" impacts in the North Atlantic Ocean near Cape Hatteras, sending out a tsunami over 400 meters tall that floods out the global Atlantic coastlines and reaches as far inland as the Ohio and Tennessee Valleys. Jenny, her father, and Sarah's parents all die, along with countless more. Every city near the Atlantic Ocean is destroyed, including New York City, Philadelphia, and Washington, D.C. Leo and Sarah manage to get high enough in the mountains to avoid the wave, along with thousands of others" see:
http://en.wikipedia.org/wiki/Deep_Impact_(movie)
As you can see , in real life the tallest recorded tsunami was 524 m ! Below is a link to this mega-tsunami.
http://t14web.lanl.gov/Research/TDAC2000/mader.tsunami.00.pdf
July 9, 1958: A huge landslip caused a tsunami in the fjord shaped Lituya Bay, Alaska, USA. It travelled at over 150 km/h. It was the worlds tallest recorded tsunami at 524 m (1719 ft).
1883 - Krakatoa explosive eruption The island volcano of Krakatoa in Indonesia exploded with devastating fury in 1883, blowing its underground magma chamber partly empty so that much overlying land and seabed collapsed into it. A series of large tsunami waves was generated from the collapse, some reaching a height of over 40 metres above sea level.
Tsunami waves were observed throughout the Indian Ocean, the Pacific Ocean, the American West Coast, South America, and even as far away as the English Channel. On the facing coasts of Java and Sumatra the sea flood went many miles inland and caused such vast loss of life that one area was never resettled but went back to the jungle and is now the Ujung Kulon nature reserve.
For instance, the tsunami which hit the island of Hokkaido on July 12, 1993 created waves as much as 30 m (100 ft) tall - as high as a 10-story building. The port town of Aonae was completely surrounded by a tsunami wall, but the waves washed right over the wall and destroyed all the wood-framed structures in the area. The wall may have succeeded in slowing down and moderating the height of the tsunami but it did not prevent major destruction and loss of life.