Hollywood movies may have wrongly depicted massive waves wiping out coastal cities when an asteroid crashes into the ocean, a new study has found.

New simulations show that real asteroids do not make a splash because the crash releases most of its energy hurling water up into the atmosphere, and very little on making waves.

"The folklore has been that tsunamis from impactors will be the danger," said Galen Gisler from Los Alamos National Laboratory in the US.

Researchers ran 3D simulations that modelled wave formation from falling rocks of various sizes and found that the waves formed by smaller asteroids resemble landslide tsunamis on Earth.

"The splash wave can be very dangerous - out to tens of kilometres - but beyond that, they fall away more sharply," Gisler said.

He found that most of the energy (80 per cent) from an impact is spent vaporising water and forming a crater, 'Space.com' reported.

The remaining 20 per cent throws most of the liquid water up into the atmosphere, where it has the potential to affect weather patterns, said Gisler.

He estimated that only a tenth of one per cent of the kinetic energy from an impact is spent forming waves. Those waves can still be massive, but they break up quickly.

"It is very ineffective at actually producing a wave. The waves do not propagate very well," Gisler added.