Colombo, Sep 11 (IANS): Sri Lanka and much of the Indian Ocean region are vulnerable to as large or even larger tsunamis than the one that resulted from the 2004 magnitude 9.2 Sumatra earthquake, says a study.

The Dec 26, 2004 Sumatra earthquake resulted in a trans-oceanic tsunami, killing more than 200,000 people.

Sri Lanka, and much of the Indian Ocean, is affected by large tsunamis at highly variable intervals, showed the study on the frequency of past giant earthquakes in the Indian Ocean region.

"The accumulation of stress in the region could generate as large, or even larger tsunamis than the one that resulted from the Sumatra earthquake," researchers said.

For the study, the researchers collected and analysed 22 sediment cores - materials trapped within are scanned to re-construct past ocean conditions - from Karagan Lagoon, Hambantota in south-eastern Sri Lanka, to examine the historical record of giant earthquakes along the Sumatra-Andaman subduction zone, where the Indo-Australian plate and Eurasian plate meet.

"These results are very important to better understand the tsunami hazard in Sri Lanka," said lead author of the study, Kelly Jackson from the University of Miami (UM) in the US.

"A scary result is a 1,000-year time period without a tsunami, which is nearly twice as long as the lull period prior to the 2004 earthquake," said Falk Amelung, professor of geophysics at UM.

"This means that the subduction zone is capable of generating earthquakes almost twice as big as in 2004," Amelung added.

The study appeared online in the journal Geology.