The magnitude of the wave would be 1.5-2.0 metres high - far less than the 5-12 metre tsunami on December 26, 2004, said Norwegian geologist Dr Kjeel Karlsrud, who conducted a risk study recently.

"The next tsunami should happen within the next 50 to 100 years in Thailand if a quake with a magnitude of 8.5 on the Richter scale occurs underwater in the area of the Sumatra islands. The centre of the afflicted area would be similar to the first tsunami," Dr Karlsrud said.

The six provinces hit in 2004 and Koh Phrathong would still be the centre of the impact, he predicted.

"The most worrying issue is improper land use in those areas that might cause higher damage than it should," he said.

Worrawut Tantiwanich, director of the Department of Mineral Resources' Environmental Geology Division, said prevention measures were needed for the area even though the possibility of a second tsunami was a long way off.

"Warning systems and the improvement of land use in the areas potentially affected should start now," he said.

Among the suggested measures, he said, his authority had concluded that public parks should be built in particular areas as natural barriers to decrease the strength of a tsunami.

"Haad Patong should extend its emergency evacuation routes to 500 metres and add more such routes to the existing seven, while Baan Nam Khem should have 10 similar routes. Together with the efficient warning systems, these should be acceptable prevention measures," Worrawut said yesterday.

He spoke after a meeting with experts and officials from Asean countries on post tsunami measures. 

Janjira Pongrai

The Nation