Earth: Permanently Deformed By Chilean Earthquakes?

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Has Earth been permanently deformed by earthquakes in Chile?

More than a century of research suggested that the planet rebounds after quakes, with the crust springing back like elastic over the course of months to decades.

Now scientists aren't necessarily sure that's the case.

Earth Quake

Richard Allmendinger of Cornell University says that earthquakes of magnitude 7 or greater caused caused the crust in northern Chile to crack permanently.

Structural geologist Allmendinger and his graduate students went to Chile to study something else, he told NBC News, but made a surprising discovery.

Once there, "our Chilean colleague, Professor Gabriel González of the Universidad Católica del Norte, took us to a region where these cracks were particularly well-exposed."

In northern Chile, "the driest place on Earth, we have a virtually unique record of great earthquakes going back a million years," Allmendinger said.

"Our record of upper plate cracking spans thousands of earthquake cycles."

Researchers say a small but significant 1-10 percent of the deformation caused by 2,000 to 9,000 major quakes over the past 800,000 to 1 million years was permanent.

The alterations to the Earth that are not being reversed involve cracks varying from millimeters to meters large in the crust of the Atacama Desert.

The study, April 28 in the journal Nature Geoscience, "calls into question" the previous models that geophysicists currently use to study quakes.

"Their models generally assume that all of the upper-plate deformation related to the earthquake cycle is elastic - recoverable, like an elastic band - and not permanent."