Chile Earthquakes: How They Have Deformed The Earth

A new study reveals that earthquakes can permanently deform the Earth, based on information obtained from earthquakes in Chile.

While most research conducted over the past century claims that the Earth typically rebounds after earthquakes, the new research conducted by a team of researchers, led by Cornell University's Richard Allmendinger, reveals that crust in northern Chile cracked as a result of earthquakes of magnitude seven or higher.

"My graduate students and I originally went to northern Chile to study other features," Allmendinger said. "While we were 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."

"I still remember feeling blown away — never seen anything like them in my 40 years as a geologist — and also perplexed," Allmendinger told OurAmazingPlanet. "What were these features and how did they form? Scientists hate things like this unexplained, so it kept bouncing around in my mind."

The dry region of northern Chile is a particularly good location for the study of earthquakes, preserving thousands of earthquake cycles, far more than those preserved in other regions. Because of the higher degree of cycle preservation, the researchers were able to examine earthquake behavior over a longer period, facilitating pattern recognition. They found that between one and 10 percent of the Earth's deformation that took place as a result of 2,000 to 9,000 earthquakes over the past 800,000 to one million years was permanent. These deformations manifested themselves as cracks in the Atacama Desert.

"It is only in a place like the Atacama Desert that these cracks can be observed — in all other places, surface processes erase them within days or weeks of their formation, but in the Atacama, they are preserved for millions of years," Allmendinger said. "We have every reason to believe that our results would be applicable to other areas, but is simply not preserved for study the way that it is in the Atacama Desert."

The results suggest that deformations resulting from earthquakes are less elastic than previously thought. The study is published online as of April 28 in the journal Nature Geoscience.

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