Ground movement of at least 0.4 inch occurred everywhere [on earth]
The quake resulted from the longest fault rupture ever observed — 720 miles to 780 miles, which spread for 10 minutes. A typical earthquake lasts for 30 seconds.
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, the 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 by 0.004 inch.
In Sri Lanka, more than 1,000 miles from the epicenter, the ground moved nearly 4 inches.
The temblor also "delivered a blow to our planet" that was felt for weeks, according to 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 scientists were able to measure for weeks afterward. A similar phenomenon was first noted in a 1960 quake in Chile.