"29075) 1950 DA is a near Earth asteroid. It is notable for having the highest known probability of impacting Earth,
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If 1950 DA continues on its present orbit, it will approach near to the Earth on March 16, 2880. However, over the intervening time, its rotation will cause its orbit to change (by the Yarkovsky effect). Available radar and optical data suggest two possible pole directions[2]; one trajectory misses the Earth by tens of millions of kilometers, while the other has an impact probability of 1⁄300."
http://en.wikipedia.org/wiki/(29075)_1950_DA

"March 16, 2880, is the day the asteroid known as 1950 DA, a huge rock two-thirds of a mile in diameter, is due to swing so close to Earth it could slam into the Atlantic Ocean at 38,000 miles per hour. The probability of a direct hit is pretty small, but over the long timescales of Earth's history, asteroids this size and larger have periodically hammered the planet, sometimes with calamitous effects.
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For the simulation, the researchers chose an impact site consistent with the orientation of the Earth at the time of the predicted encounter: in the Atlantic Ocean about 360 miles from the U.S. coast. Ward summarized the results as follows:

The 60,000-megaton blast of the impact vaporizes the asteroid and blows a cavity in the ocean 11 miles across and all the way down to the seafloor, which is about 3 miles deep at that point. The blast even excavates some of the seafloor. Water then rushes back in to fill the cavity, and a ring of waves spreads out in all directions. The impact creates tsunami waves of all frequencies and wavelengths, with a peak wavelength about the same as the diameter of the cavity. Because lower-frequency waves travel faster than waves with higher frequencies, the initial impulse spreads out into a series of waves.
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The waves propagate all through the Atlantic Ocean and the Caribbean. The waves decay as they travel, so coastal areas closest to the impact get hit by the largest waves. Two hours after impact, 400-foot waves reach beaches from Cape Cod to Cape Hatteras, and by four hours after impact the entire East Coast has experienced waves at least 200 feet high, Ward said. It takes 8 hours for the waves to reach Europe, where they come ashore at heights of about 30 to 50 feet.
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An important feature of Ward's simulation is that it enabled him to calculate the speed of the water flows created by the tsunami at the bottom of the ocean--more than 3 feet per second out to distances of several hundred miles from the impact.

"That's like a raging river, so as these waves cross the ocean they're going to stir up the seafloor, eroding sediments on the slopes of seamounts, and we may be able to identify more places where this has happened," Ward said."
http://www.ucsc.edu/news_events/press_releases/text.asp?pid=355