Tsunami built up low-lying Maldives

At Phi Phi Island, Thailand, the tsunami had a much greater impact. Picture / Reuters

The devastating 2004 Boxing Day tsunamis in the Indian Ocean hit the low-lying Maldives head-on but actually built up some of the islands, an Auckland University geologist says.

Loss of life on the Maldives as a result of the tsunami was relatively low - about 108 people - although almost every island was hit and the effect on human structures such as jetties and housing, water and health services and tourism infrastructure was severe.

But Paul Kench said less than 5 per cent of the land area was significantly changed by the tsunamis, the Discovery Channel reported on its website.

Dr Kench's before-and-after study of 13 small islands in the archipelago of 300,000 people off the coast of Sri Lanka showed the low-lying coral atolls were tougher than they looked.

"We looked for any evidence of change," said Dr Kench, whose team had surveyed the 13 small islands in 2002 and 2003, and were in a perfect position to assess the effects of the tsunamis that stuck in 2004.

The research has just been published in the March issue of the international scientific journal Geology.

The researchers found the tsunamis were not nearly as high at the Maldives as along other coasts because there was no continental shelf to build them up.

Instead, Dr Kench said, the highest in the series of tsunamis from the Great Sumatra-Andaman earthquake were only about 3m high, which washed over the 1.5m to 2m-high atolls and then kept racing toward Africa.

Most of the islands were inundated, but there were no thundering walls of water, and the islands were also spared any backwash, which doubled the scouring effect in other countries.

In the Maldives, the tsunamis scoured only the eastern sides of the islands. As much as 300mm of sand was deposited on one island, with the others gaining 50mm to 100mm.

- NZPA