[meteorite-list] New Model Predicts Fallout from Big Meteorite Strike

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 7 Nov 2011 14:59:04 -0800 (PST)
Message-ID: <201111072259.pA7Mx4tD022720_at_zagami.jpl.nasa.gov>

http://www.livescience.com/16877-model-predicts-fallout-big-meteorite-strike.html

New Model Predicts Fallout from Big Meteorite Strike
SPACE.com
November 4, 2011

A major meteorite impact on Earth could spell doomsday - or not. To
better predict what could be in store if a giant space rock slammed into
our planet, scientists have built a new model to simulate the seismic
fallout from such an event.

The model predicts how seismic waves would spread through Earth after a
meteorite collision It's the first to take into account the planet's elliptical
shape, surface features and ocean depths. In contrast, previous models have
assumed Earth is perfectly spherical and featureless, with nothing to
disrupt a meteorite's impact.

"After a meteorite impact, seismic waves travel outward across the Earth's
surface like after a stone is thrown in water," research leader Matthias
Meschede of the University of Munich said in a statement. "For the Earth, these
calculations are usually made using a smooth, perfect sphere model, but
we found that the surface features of a planet or a moon have a huge
effect on the aftershock a large meteorite will have, so it's extremely
important to take those into account."

The researchers used their new model to simulate the collision that
created the Chicxulub crater in Mexico around 65 million years ago. This
crash, which was 2 million times more powerful than a hydrogen bomb, is
thought to have wiped out the dinosaurs and much of Earth's life at the time.

The new study showed that the seismic waves resulting from the impact
would have been scattered and unfocused, causing less severe ground
displacement, tsunamis, and seismic and volcanic activity than
previously thought.

"But our results go beyond Chicxulub," Meschede said. "We can, in
principle, now estimate how large a meteorite would have to have been to
cause catastrophic events. Our model can be used to estimate the
magnitude and effect of other major impacts in Earth's past."

NASA and astronomers around the world regularly keep track of
potentially hazardous asteroids. NASA announced last month that it has
found about 90 percent of the largest, most dangerous space rocks near
our planet.

To that end, NASA is tracking a huge space rock, the asteroid 2005 YU55,
which is the size of an aircraft carrier and will fly close by the
Earth, inside the orbit of the moon, on Nov. 8. Though this is
considered a very close pass, the rock is calculated to pose no risk to
planet Earth.

Meschede developed the new model with colleagues while visiting
Princeton University through the Visiting Student Research
Collaborators program. The researchers describe their new model in the
October issue of Geophysical Journal International.
Received on Mon 07 Nov 2011 05:59:04 PM PST