Chilean quake moved entire city ten feet west

Posted by Emma Woollacott

The massive earthquake that struck the west coast of Chile last month moved the entire city of Concepcion at least 10 feet to the west, and shifted other parts of South America as far away as the Falkland Islands and Fortaleza, Brazil.

The magnitude 8.8 temblor is believed to be the fifth most powerful since instruments have been available.

Buenos Aires, a continent away from the quake’s epicenter, moved about an inch to the west. And Chile’s capital, Santiago, moved about 11 inches to the west-southwest. The cities of Valparaiso and Mendoza, Argentina, northeast of Concepcion, also moved significantly.

The research team deduced the cities’ movement by comparing precise GPS locations before and after the quake using the 25 GPS stations of the Central and Southern Andes GPS Project (CAP).

"By reoccupying the existing GPS stations, CAP can determine the displacements, or 'jumps', that occurred during the earthquake," said Mike Bevis, professor of earth sciences at Ohio State University, who said.

He said CAP hopes to expand this network to monitor the postseismic deformations that are expected to occur for many years.

Ben Brooks, an associate researcher with the School of Ocean and Earth Science and Technology at the University of Hawaii and co-principal investigator on the project, said that the event, tragic as it was, offers a unique opportunity to better understand the seismic processes that control earthquakes.

“The Maule earthquake will arguably become one of the, if not the most important great earthquake yet studied. We now have modern, precise instruments to evaluate this event, and because the site abuts a continent, we will be able to obtain dense spatial sampling of the changes it caused.

“As such the event represents an unprecedented opportunity for the earth science community if certain observations are made with quickly and comprehensively,” Brooks said.