Model shows effects of giant meteorite strike

Posted by Emma Woollacott

Ever wondered exactly what would happen if a massive meteorite hit the Earth? Princeton University scientists can show you.

They've created a new model that, they say, can more accurately simulate the seismic fallout of such an impact by taking into account Earth's elliptical shape, surface features and ocean depths. Current models use a featureless sphere.

The model simulates how seismic waves generated by a meteorite collision would spread across and within the planet.

"After a meteorite impact, seismic waves travel outward across the Earth's surface like after a stone is thrown in water. These waves travel all the way around the globe and meet in a single point on the opposite side from the impact known as the antipode," says lead author Matthias Meschede of the University of Munich.

Our model shows that because the Earth is elliptical and its surface is heterogeneous those waves travel with different speeds in different areas, changing where the waves end up on the other side of the world and the waves' amplitude when they get there. These waves also are influenced by the interior."

The researchers started by simulating the meteorite strike that caused the Chicxulub crater in Mexico 65 million years ago, an impact two million times more powerful than a hydrogen bomb that's believed to have triggered the extinction of the dinosaurs.

They found that the impact's seismic waves would be scattered and unfocused, resulting in less severe ground displacement, tsunamis, and seismic and volcanic activity than previously theorized.

There's a prominent theory that the meteorite triggered huge volcanic eruptions that changed the climate, originating in the Deccan Traps in India - roughly on the opposite side of the Earth from the Chicxulub crater at the time. But the new model implies this is unlikely.

"Regarding the mass extinction, we saw from our measurements that a Chicxulub-sized impact alone would be too small to cause such a large volcanic eruption as what occurred at the Deccan Traps," says Meschede.

"Our model shows that the antipodal focusing of the seismic wave from such an impact was hugely overestimated in previous calculations, which used a spherical-Earth model."