New Zealand Quakes Made Earth's Crust Weaker

How nasty were the deadly quakes that hit New Zealand one after another in 2010 and 2011? So bad that they appear to have seriously weakened the Earth's crust, scientists reveal in a new study. Geologists had previously believed that the strength of the Earth's crust was more or less constant. But in New Zealand, the researchers used seismic waves to create an image of the rock, and found areas deep below the surface that were dramatically weaker, spreading out 3 miles around the fault, LiveScience explains.

"Such widespread weakening is not common, and has not been previously reported," says the study's leader. While the quakes didn't record particularly high magnitudes, they released an abnormally high amount of energy. The quakes wound up leaving 185 people dead, and destroying roughly a third of the buildings in the city of Christchurch. (More geology stories.)