Tag Archives: Planetary science

Credit: Ian Joughin, CC BY-NC-SA 3.0

Building a Better Glacial Speedometer

Greenland is the land of escaping lakes. In the summer, when soot lands on the ice sheet’s snowy surface and the Sun begins to melt the snow, bright blue lakes form on top of the ice. Just as on land, the water seeks a way down.

Sometimes, instead of carving surface channels, water trickles into the ice sheet through crevasses and vertical shafts called moulins. In the most dramatic cases, a lake can burst through a kilometer-thick ice sheet and rush to the bottom of the glacier in a forceful waterfall. There, under high pressure, water may help the glacier glide a little faster over the rock below.

Just how fast, however, is the subject of an ongoing debate. Continue reading

The Sound of Sliding

December-2013-coverWhen a landslide tore through a remote Alaskan valley in July, no one was there to bear witness. But hours later, geoscientist Colin Stark of the Lamont-Doherty Earth Observatory spotted the event in the pattern of seismic waves passing through the Earth’s crust. Within days, using data from earthquake sensors and satellite images, he and colleague Göran Ekström were able to estimate, from their lab in New York, the landslide’s size, and even determine its path.

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