Last year's Sumatra-Andaman earthquake shook the ground everywhere on Earth's surface and left the planet still trembling weeks later.
The most powerful earthquake in more than 40 years, which triggered the Asian tsunami, resulted from the longest fault rupture ever observed - 720 miles to 780 miles, which spread for 10 minutes, also a record.
A typical earthquake's duration would be 30 seconds.
The December quake was the first of its size to be measured and studied by the new worldwide array of digital seismic instruments.
Those results are starting to come in, with a special section of a half-dozen research papers on the quake appearing in the most recent issue of the journal Science.
The earthquake and resulting tsunami, which swept across the Indian Ocean, killed more than 176,000 people in 11 countries and left about 50,000 missing and hundreds of thousands homeless.
The quake occurred where two of the giant plates that form the surface of the Earth grind together.
At that spot the Eurasian plate was being pulled downward by the descending Indo-Australian plate. The quake released the edge of the Eurasian plate, which sprang up, lifting the ocean floor and sending the sea water off in the giant wave that killed so many, researchers reported.
They said the higher sea floor displaced so much water from the Bay of Bengal and the Andaman Sea that sea level worldwide was raised 0.004 inch.
"No point on Earth remained undisturbed," wrote Roger Bilham of the University of Colorado. Indeed, ground movement of as much as 0.4 inch occurred everywhere on Earth's surface, although it was too small to be felt in most areas.
The earthquake "delivered a blow to our planet" that was felt for weeks, noted a team of researchers led by Jeffrey Park of Yale University.
His group calculated that the quake caused the planet to oscillate like a bell, at periods of about 17 minutes, which they were able to measure for weeks afterward. A similar phenomenon was first noted in the 1960 quake in Chile.
The initial December 26th Sumatra quake is estimated to have had a magnitude of 9.1 to 9.3; a second quake to the south on March 28th registered 8.6.
Among the other findings reported in the various papers:
- In Sri Lanka, more than 1,000 miles from the epicentre, the ground moved nearly four inches.
- The rupture spread from south to north, resulting in a Doppler effect in instruments measuring it. Seismometers in Russia recorded the quake at a higher frequency because it was moving toward them; those in Australia measured a lower frequency as it moved away.
- When the surface waves from the Sumatra quake reached Alaska they triggered 14 local earthquakes in the Mount Wrangell area.
AP