US scientists have found evidence of a mega tsunami that had hit Tonga in the past few thousand years and say another giant wave could strike the region again.
The scientists from the University of Texas studied massive boulders of coral, some the size of a house, found 400 metres from the shoreline on Tonga's main island Tongatapu.
Team leader Dr Matthew Hornbach says it's likely the boulders were deposited when a nearby underwater volcano exploded some ten to hundred-twenty thousand years ago.
Dr Hornbach says such an event could happen again.
"We know that these things have happened in the past. These are highly active volcanoes that are constantly erupting and there's good evidence that they are always pretty active, so I think yes it could happen, every few hundred or few thousand years you will have an eruption event. Whether or not a tsunami will occur, it's hard to say, but it's a possibility."
Dr Matthew Hornbach says Tonga and surrounding countries should consider plans in case such an event repeats itself.