Tsunami quake caused 1000km seafloor rupture

LONDON - The earthquake that triggered December's devastating Indian Ocean tsunami caused a 1000km rupture in the sea floor say scientists.

Using data from 60 Global Positioning System monitoring sites in southeast Asia, scientists at ENS/CNRS research institute in Paris calculated the unprecedented scale of the quake.

"We show that the rupture plane for this earthquake must have been at least 1000 kilometres long," said Christophe Vigny who headed the research team.

The magnitude 9.15 earthquake, the biggest in 40 years, erupted off the coast of Indonesia's Sumatra island. It triggered a tsunami that left up to 232,000 people dead and missing in 13 Indian Ocean countries.

Indonesia, Sri Lanka, India and Thailand were most affected.

Vigny and his colleagues used displacement data recorded at the GPS sites across southeast Asia to construct and test models of the length of the rupture and the direction of thrust.

The satellite navigation network sites in Indonesia, Malaysia and Thailand were between 400 to 3000km from the epicentre of the December 26 quake.

"Small but significant seismic jumps are clearly detected more than 3,000 kilometres from the earthquake epicentre," Vigny said in a report in the science journal Nature.

Scientists have warned that a second earthquake in South Asia on March 28 increased stress on fault lines in the region, making it more vulnerable to another rupture and a tsunami.

- REUTERS