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Chilean Quake Observers Say Patterns Are Predictable

Installation of a Creepmeter on the Plate-Boundary Observatory in Chile, the device measures tektonic motions to a hundredth of a millimeter along a fault zone. (Image credit: GFZ)

The shifts and breaks in Earth's crust from the massive earthquake that shook Chile in February were predicted by German scientists based on their studies of past earthquake stress, the scientists now say, adding that their technique could be used to anticipate the fractures from future quakes.

Researchers from the GFZ German Center for Geosciences were able to anticipate and record the magnitude 8.8 temblor in its entirety using a modern network of instruments on the ground, making it the largest earthquake so thoroughly monitored.

According to the researchers, the complex fracture pattern created by the earthquake centered near Concepción, in central Chile, had been seen in the area before. GPS observations that track subtle movements of the Earth's surface showed the same pattern of stress had accumulated during tectonic plate movement since the last major earthquake there, 175 years earlier.

The researchers used GPS observations to reconstruct the deformation of land along the Chilean coast during the decade preceding the Feb. 27 earthquake.

A computer simulation showed the connection between observed surface deformations and locking between tectonic plates. Using this information, researchers were able to "image" the stress buildup and predict that the stress release of the next quake would be similar to the stress release during the one of 1835, which had been observed by Charles Darwin.

When the earthquake struck Feb. 27, they found the stress release was very similar to what they had predicted, they report in the Sept. 9 edition of the journal Nature.

Because of this pattern, the researchers say certain indicators of the onset of these earthquakes can be used to forecast the magnitude and possible fracture patterns of future earthquakes.

"It thus offers a unique opportunity to compare detailed observations prior to the earthquake with those taken during and after it, and to re-evaluate hypotheses regarding the predictability of such events," said study team member Onno Oncken, head of the GFZ center's Department of Geodynamics.

The GFZ German Center for Geosciences, based in Potsdam, is part of the national Helmholtz Association of scientific and medical institutes.

The center said the quake removed all the stress that had built up since Darwin's time, making it unlikely that an earthquake of similar magnitude would recur in the area in the near future. It added.

However, "earthquake prediction is still impossible," study co-author Matthias Rosenau told OurAmazingPlanet.

OurAmazingPlanet Staff