© LiveScience.com/Fred Pollitz, USGS A map of the earthquakes triggered around the globe (shown as black dots) within a week of the April 11, 2012 earthquake off the coast of Sumatra
On April 11, a massive magnitude 8.6 earthquake shook the floor of the Indian Ocean off Sumatra. It wasn't just unusual because of its size - the 10th largest quake in the last century - it also set off a series of quakes around the world for up to six days afterward, according to a study published today (Sept. 26) in the journal
Nature.
"Until now, we seismologists have always said, 'Don't worry about distant earthquakes triggering local quakes,'" said Roland Burgmann, an earth and planetary scientist at UC Berkeley, in a statement. "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."
The study found that some quakes were triggered within a few hours, while in other places the seismic waves from the Sumatran quake primed temblors to happen for up to six days later.
The findings should remind those living in seismically active areas that the risk from a large earthquake could persist, even on the opposite side of the globe, for more than a few hours, the study scientists said.
Another study also published today suggests that the quake marks the birth of a new tectonic plate beneath the Indian Ocean.