Large, Icy Avalanches Plague A Saturn Moon

Ice avalanches on Rhea behave differently than those on Iapetus. On Rhea, ice lands in a debris pile beneath the crater wall instead of scooting miles into the crater. Rhea is roughly the same size as Iapetus and has an icy surface, but it’s not out-of-round. Its topography is less rugged and its craters are not as deep. So, on this icy moon, icefalls do not gather speed, and the ice never becomes slippery (Photo : NASA/JPL/SSI/LPI)

If you think that landslides on Earth are formidable, you should see the ones on one of Saturn's moon.

"We see landslides everywhere in the solar system," says Kelsi Singer, graduate student in earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, "but Saturn's icy moon Iapetus has more giant landslides than any body other than Mars."

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The reason for these massive landslides is due to the topographical nature of the moon.

Not only is the moon out-of-round, but the giant impact basins are very deep, and there's this great mountain ridge that's 20 kilometers (12 miles) high, far higher than Mount Everest," says William McKinnon from the Washington University in Saint Louis.

"So there's a lot of topography and it's just sitting around, and then, from time to time, it gives way."

The giant ice avalanches even behave strangely. A lot of the landslides seem to lose their friction on the way down. Instead of simply tumbling down, the landslides can even move horizontally due to the eclectic nature of the moon.

Scientists from the team are looking for a reason why this possible. So far, they have speculated that cushions of air of or an incredibly lubricated surface is responsible for this phenomenon.

There are more mechanisms proposed for fiction reduction than I can put on a PowerPoint slide," Singer said.

"Landslides on Iapetus are a planet-scale experiment that we cannot do in a laboratory or observe on Earth,. They give us examples of giant landslides in ice, instead of rock, with a different gravity, and no atmosphere. So any theory of long runout landslides on Earth must also work for avalanches on Iapetus