Nature:
Last year's
largest
earthquake took place on 29 September in the Samoan islands
and, with its 12-meter-high tsunami, killed 192 people in
American Samoa, Samoa, and Tonga. As
Nature's Richard Lovett reports, evidence from buoys
tethered to the sea floor, seismographs, and GPS monitors
indicates that the seismic disturbance consisted of three
earthquakes: one of magnitude 8.1, which struck first, and two
of magnitude 7.8, which followed in the next two minutes. The
mostly horizontal displacement of the 8.1 quake would not have
unleashed a deadly tsunami on its own, but it did trigger the
other two quakes, whose mostly vertical displacement caused the
tsunami.
