Aug 11 2014

Icequakes triggered by earthquakes

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In 2010, a powerful magnitude-8.8 earthquake struck off the coast of central Chile, rocking much of the country and producing tremor as far away as Argentina and Peru. But a new study suggests its effects were felt even farther away—in Antarctica. In the wake of the Maule temblor, the scientists found, several seismic stations on the frozen continent registered "ice quakes," probably due to fracturing of the ice as the planet's crust shook. Earthquakes are already known to affect Antarctica’s ice shelves, thanks to the tsunamis they can spawn. Tsunami waves can propagate for great distances across the ocean; if the waves reach Antarctica’s ice shelves - the floating platforms of ice surrounding the continent—they can push and pull on the ice, promoting fractures and ultimately helping large chunks of ice break off, or calve.
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Jul 22 2013

Antarctica Ice Sheet less stable than previously thought

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Earth continues to hit temperature and greenhouse gas milestones—just a couple of months ago, multiple stations measured carbon dioxide concentrations in the atmosphere of 400 parts per million, the highest in several million years. Many studies have tried to estimate how much and how rapidly the two great ice sheets covering Greenland and Antarctica might melt—and the one reassuring point has been the apparent relative stability of the eastern (and, by far, larger) half of the Antarctic Ice Sheet. Now, a new study of past melting in East Antarctica suggests that over the long haul, the "stable" ice sheet may be more vulnerable to warming than thought. To study possible future melting of the ice sheets, many scientists look to the past. Current warm temperatures and high greenhouse gas conditions are reminiscent of the warm Pliocene Epoch that lasted from 5.3 million to 2.6 million years ago. "Early and middle Pliocene global temperatures and greenhouse gas concentrations are probably the closest analog in Earth's history to the present climate on this planet and the climate conditions we will encounter before the end of this century," says Claus-Dieter Hillenbrand, a sedimentologist at the British Antarctic Survey in Cambridge, U.K., who was not involved in the study.
Categories: News