Massive waves like a tsunami could inundate coastal cities if an asteroid were to plunge into the oceans at certain locations, says a computer simulation of the same.
If it hits the continental shelf off the Maryland coast, the asteroid could produce 23-foot-high (seven metres) waves that would flood New York to Georgia while a similar impact off the coast of California could flood major power plants along the coast.
Big asteroid impacts like the one believed to have sounded the death knell for dinosaurs 65 million years ago are rare. Smaller ones like the 2013 Chelyabinsk in Russia that have potential for damage albeit on a smaller scale are more frequent.
It is the danger from these smaller asteroids that the present Lawrence Livermore National Laboratory work tries to gauge with a computer simulation.
Asteroids of about 165 feet (50 metres) in diameter crashing into the ocean could produce waves up to 10 feet (3 metres) high, the study notes.
Even a five-foot (1.4-metre) rise in sea as predicted from climate change could flood many power plants on the western California coast.
But experts are questioning the accuracy of such models pointing out that much is not known about how waves would break in the ocean on such an impact.
Major ocean impacts in the past haven't caused tsunamis, H Jay Melosh, a planetary scientist at Purdue University in Indiana told Live Science.
Another upcoming study found that the Eltanin impact, which left a huge crater in the ocean floor off the coast of Chile 2.1 million years ago, didn't cause a tsunami despite being caused by an asteroid measuring 0.9 to 1.2 miles (1.5 to 2 kilometres) in diameter.
Melosh points out that chances are that a big wave triggered by an impact would be turbulent and break immediately right next to the impact and not be carried as a tsunami.
Interestingly, a recent study which looked at fractures in the Barberton greenstone rock belt in South Africa concluded that a massive asteroid 48 kms wide struck the ocean basin 3.26 billion years ago near present day South Africa, deforming the seafloor, generating seismic waves and giant tsunamis several hundred feet high.
The impact released a huge amount of energy and even permanently altered the tectonic plates of the early Earth, the study said. But that class of asteroid impacts are rare.