A devastating "megathrust" earthquake could occur at any time off the Indonesian island of Sumatra, according to new research. Previous quakes have failed to release all of the energy that has built up over hundreds of years, leaving the fault zone vulnerable to another large earthquake.
Using GPS, field measurements, radar data and seismological records, a team of international researchers investigated the parameters and reconstructed the events of two massive earthquakes, measuring 8.4 and 7.9 on the Richter scale, which occurred in the Mentawai area in 2007.
Previous models of how earthquakes work had suggested that the same fault would rupture in the same way and at regular, predictable time intervals. But the researchers found that the 2007 quakes ruptured only a fraction of the area affected by the giant 1833 earthquake, indicating that a tectonic plate boundary can rupture in different patterns depending on local differences in stress.
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http://www.newscientist.com/article/dn16192-megathrust-earthquake-could-hit-asia-at-any-time.html