Posted by --! on August 24, 2005 at 10:07:26:|
David Adam, science correspondent
Wednesday August 17, 2005
Thousands of people were killed when the Boxing Day tsunami struck Sri Lanka because poachers had removed coral reefs that would have shielded the coastline from the worst of the waves.
Scientists from the US and Sri Lanka who have surveyed the area say the pattern of destruction onshore matches the illegal mining of coral offshore.
In the south-western town of Peraliya, where the research team found coral removed, a 10-metre wave surged more than a mile inland and killed 1,700 people when it swept a passenger train 50 metres off its tracks. Two miles south in Hikkaduwa where the intact coral reef is protected by hotel owners as a tourist resource, the wave reached a height of three metres, and went inland just 50 metres, causing no deaths.
The difference is not attributed to coastline features but the fact that the intact coral, just a few metres from the beach, blocked the wall of water and significantly reduced its height.
Witnesses to the tsunami reported a visible shrinking in the wave when it hit coral. In other places, the blocked water surged through man-made holes in the coral reefs and went on to lash the shore with greater force.
Intact coral reefs could explain how the low-lying Maldives escaped relatively unscathed despite being in the direct path of the tsunami.
Harinda Joseph Fernando, a Sri Lankan fluid dynamics expert at Arizona State University who led the research, said governments needed to be more careful about stopping coral poaching and the destruction of beaches' natural defences. His team published its findings yesterday in Eos, the newspaper of the American Geophysical Union.
Mining for coral is big business in Sri Lanka where it is sold to tourists and used in paint making. The government rarely enforces laws against the practice.