UPI in English  |   UPI Arabic  |   UPI en Español  |   UPIU

Study: Earthquakes have distant impacts

Published By United Press International
BERKELEY, Calif., Sept. 26 (UPI) -- A large earthquake in the East Indian Ocean triggered temblors worldwide for nearly a week by priming distant faults to rupture, seismologists say.

The April 11 earthquake off Sumatra was unusually large and, like a few other recent large temblors, triggered small quakes during the 3 hours it took for seismic waves to travel through Earth's crust.

However some faults weren't rattled enough by the seismic waves to fail immediately but were primed to break up to six days later, researchers at the University of California, Berkeley, reported Wednesday.

Seismologists said their analysis found five times the expected number of quakes during the six days following the April 11 quake and aftershock.

The findings should be a warning to those living in seismically active regions worldwide that the risk from a large earthquake could persist -- even on the opposite side of the world -- for more than a few hours, researchers said.

"Until now, we seismologists have always said, 'Don't worry about distant earthquakes triggering local quakes,'" earth and planetary science Professor Roland Burgmann said.

"This study now says that, while it is very rare -- it may only happen every few decades -- it is a real possibility if the right kind of earthquake happens."

It is possible the East Indian Ocean quake triggered a cascade of smaller, undetectable quakes on distant faults that led to larger ruptures later on, Burgmann said.
© 2012 United Press International, Inc. All Rights Reserved. Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.

Photo Gallery
1 of 1
Tour de France concludes in Paris
Race winner Bradley Wiggins of Great Britain (C) stands between second place finisher Christopher Froome of Great Britain (L) and third place finisher Vincenzo Nibali of Italy on the presentation podium following the final stage of the Tour de France in Paris on July 22, 2012. Wiggins of Great Britain became that country's first ever overall winner of the Tour de France. UPI/David Silpa