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Major earthquake expected along tsunami's fault line

Another major earthquake along the same fault line that sparked the devastating 2004 Indian Ocean tsunami is likely in the next several decades—and it could unleash as much or more destruction, new research suggests.

The tsunami, which killed an estimated 250,000 people, was sparked by a magnitude 9.2 earthquake along the Sunda fault off the coast of Sumatra, Indonesia. A major 8.4 temblor and aftershocks along a southern section of that fault called the Mentawi patch shook up the region last year.

Now, analysis of coral growth patterns along the Mentawi patch suggests that the 2007 quake may have been just the first episode in an "earthquake supercycle," or set of large quakes that have occurred in the region roughly every 200 years for the past seven centuries. Sections of the Earth's crust called tectonic plates are likely to rupture again under the Mentawi patch within several decades, possibly generating a magnitude 8.8 temblor, according to research published in this week's Science.

"If previous cycles are a reliable guide, we can expect one or more very large west Sumatran earthquakes...within the next two decades," co-author Kerry Sieh, a professor at the California Institute of Technology's Tectonics Observatory, said at a press conference, according to Reuters.

Were such a quake to cause another tsunami, it could equal or exceed the damage of the 2004 disaster in the country's Aceh province, which bore the brunt of the death then, write the authors, who are also from the University of Minnesota, the Indonesian Institute of Science and National Taiwan University.

The scientists studied coral because—like growth rings on trees—the reefs record the history of the sea level where they grow. When tectonic plates push the ocean bed up, the sea level goes down, and coral can no longer grow vertically. It can, however, grow outward, so those cross sections reveal the pattern of tectonic movement.

Indonesia unveiled a new tsunami warning system last month.

Earthquake researchers at the University of Nevada, Reno yesterday simulated a magnitude 8.0 temblor on a bridge model, testing whether future construction technologies that incorporate nickel-titanium bars, elastomeric materials, and polyvinyl fiber concrete would withstand such a quake. The bridge columns swayed and cracked when scientists shook the tables where the concrete model was built, the university reports.

“These were all new designs, and we’ve learned they performed better than conventional construction,” M. Saaid Saiidi, the simulation's principle researcher, told the school's blog. “Of the three new designs we tested, two of them had very little damage. We are quite pleased with the results so far.”

For more on earthquakes, see our in-depth report.

Dead reef killed by 2007 magnitude 8.4 earthquake/Science

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