Posted for Ashley Yeager

The earthquakes aren’t over for the Indonesian island of Sumatra. In 2004, a devastating 9.2 magnitude earthquake and tsunami killed 225,000 people when it struck the Indonesian area. Now new research suggests that the area, part of a belt of intense seismic activity known as the “Pacific Ring of Fire”, could take another hit in the future.

Geologists have been monitoring the area using satellites to measure ground movements. They’ve also studied geological evidence of what has happened there in the past. Surprisingly, despite a series of quakes in 2005 and 2007, measurements of the quake zone around the Mentawai islands off Sumatra’s west coast show there is still a large amount of stress built up in the region. The findings are published in the 4 December issue of Nature.

In the 2007 quakes, for example, “the slippage of the [tectonic] plates was patchy, and it didn’t release all the strain that had accumulated”, first author of the new study, Ali Ozgun Konca, says in a California Institute of Technology press statement. In fact, only a quarter of the energy that had accumulated since 1833 was released, leaving enough pent-up to trigger another giant earthquake at any time.

“We may have to wait a long time, but there’s no reason to think it’s over,” says Jean-Philippe Avouac, director of Caltech’s Tectonics Observatory a coauthor on the paper.

The results suggest that the event could be anywhere between magnitude 8.2 and over 9, John McCloskey, a geophysicist at the University of Ulster, UK, who was not involved in the research, told New Scientist.