The magnitude 8.8 quake that struck near Maule, Chile, Feb. 27 moved the entire city of Concepcion 10 feet to the west. [via wired]
Precise GPS measurements from before and after the earthquake, the fifth largest ever recorded by seismographs, show that the country’s capital, Santiago, moved 11 inches west. Even Buenos Aires, nearly 800 miles from the epicenter, shifted an inch. The image above uses red arrows to represent the relative direction and magnitude of the ground movement in the vicinity of the quake.
The analysis comes from a project led by Ohio State earth scientist Mike Bevis that has been using GPS to record movements of the crust on Chile since 1993. The area is of particular interest to geoscientists because it is an active subduction zone, where an oceanic plate is colliding with a continental plate and being pushed into the Earth’s molten mantle below.
The world’s largest recorded earthquakes since 1900 have all occurred in subduction zones, including the largest quake ever recorded, which was a magnitude 9.5 in 1960 in Chile not too far from February’s earthquake. The second largest was a 9.2 in Alaska in 1964, and the third was the magnitude 9.1 Sumatra quake of 2004 that created the tsunami that killed more than 200,000 people. The fourth largest quake was a magnitude 9 on Russia’s Kamchatka peninsula.
Bevis’ team hopes to add 50 more GPS stations to its current 25 to better measure the movement and deformation of the crust that will continue for years.
“The Maule earthquake will arguably become one of the, if not the most important great earthquake yet studied,” said project scientist Ben Brooks of the University of Hawaii in a press release. “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.
Images: University of Hawaii
