The data comes from Global Positioning System (GPS) stations that have been dotted across Southeast Asia in a network designed to monitor land movements caused by seismic activity.

Initial estimates were of a seabed rupture that spread northwards from a point just west of Sumatra, on a weakened fault some 450 kms (250 miles) long.

But the latest paper confirms later calculations that the rupture was at least 1,000 kms (625 miles) long, ending at a point just south of Myanmar, and that it proceeded at a dizzying speed rather than at a slow "aseismic" pace.

The quake was so powerful that less than 10 minutes after the event, land in Phuket, Thailand, had been shoved horizontally by 27 centimetresinches), the sensors showed.

Movements of between five and 10mm (0.2 to 0.4 inches) were recorded at sites up to 3,000 kilometers (1,875 miles) from the quake's epicentre, according to GPS-linked monitors at Kunming, southern China; Bangalore and Hyderabad in southern India; and Sabah, eastern Malaysia.

The study, published in the British weekly science journal Nature, is lead-authored by Christophe Vigney, a geologist with France's National Centre for Scientific Research

In March, scientists estimated the temblor measured 9.3 on the Richter scale -- more than twice as powerful as originally thought and the second biggest quake ever recorded.

The event released so much strain along that particular fault that in theory there should be no quake of similar magnitude, or a similar tsunami, there for another 400 years, according to the March study, written by Seth Stein and Emile Okal of Northwestern University, Illinois.

But farther south, it is a different picture, for the tension has been displaced onto further sections of a different kind of fault, sowing the seeds for further big quakes, they said.

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