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Studying Chile’s Geological Shift

Posted on | March 12, 2010 | Comments Off

South America map

Map of South America showing the permanent ground motion due to the 2010 Chile earthquake.

Mānoa Associate Researcher Benjamin Brooks is co-principal investigator of a study to determine the geological consequences of the February earthquake in Chile. The massive magnitude 8.8 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 apart as the Falkland Islands and Fortaleza, Brazil. Also involved in the project is Assistant Researcher James Foster who is part of the Global Positioning Satellite processing effort at the Mānoa Pacific GPS Facility.

The February Chilean quake occurred where the Nazca tectonic plate was squeezed under, or “subducted,” below the adjacent South American plate. Quakes routinely relieve pent-up geologic pressures in these convergence zones.

The research team deduced the cities’ movement by comparing precise GPS locations known prior to the major quake to those almost 10 days later. The U.S. Geological Survey reported that there have been dozens of aftershocks, many exceeding magnitude 6.0 or greater, since the initial event Feb. 27.

These preliminary measurements, produced from data gathered by researchers from four universities and several agencies, including geophysicists on the ground in Chile, paint a much clearer picture of the power behind this temblor, believed to be the fifth-most-powerful since instruments have been available to measure seismic shifts.

Read the news release.

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