The south Asian tsunami of 2004: A magnitude 9.15 undersea
earthquake occurred just north of Simeulue island, off of
Indonesia's Sumatra Island on the morning of 2004-DEC-26. It was
at a depth of 30 km (19 miles), extended over about 1,200 km
(over 700 miles), and caused a sudden rise in the adjacent
seabed by several meters. The total energy released was
equivalent to about five hundred megatons of TNT. This was more
than 200 times the total explosives used during World War II --
including the two nuclear bombs. It caused the crust of the
entire Earth to vibrate by at least a few centimeters. It
triggered other earthquakes as far away as Alaska.
Reverberations could still be detected by sensitive instruments
a week later. It altered the earth's rotational speed,
shortening each day by about 3 microseconds. There have been
only two other earthquakes of greater magnitude since the year
1900. In all three cases, the rise in the seabed displaced
sufficient water to generate a massive tsunami (a.k.a.
teletsunami,