Coral could
slow tsunamis

Illegal coral mining may have
intensified destruction around
Sri Lanka, a study says

The December tsunami waves that veered around the southern tip of Sri Lanka into its southwestern coast, stripped of coral reefs by illegal mining, might have been subdued by the natural barriers, according to a study in the Aug. 16 edition of Eos.

Eastern Sri Lanka took the brunt of the Dec. 26 tsunami, triggered by the worst earthquake in 40 years. Lead study author Harinda Joseph Fernando traveled to southwestern Sri Lanka to study damage in areas where coral was being mined.

Hundreds of eyewitness accounts, diver observations and wave measurements were collected to determine that coral mining had breached natural barriers, funneling water onshore and intensifying destruction, said Fernando, professor of mechanical engineering at Arizona State University in Tempe, in the article published by the American Geophysical Union.

"It was surprising how these corals -- they're not jutting out of the ocean -- how much resistance they can have to the extent that the water column can deflect to a low-resistance area" where coral has been removed, Fernando said in an interview yesterday.

The tsunami killed more than 200,000 people and left as many as 5 million in need of basic services in a dozen Indian Ocean nations, according to the United Nations Web site.

Scientists studied the southwestern coast between Akuralla to Dodanduwa. That area took hits from two or three waves that slammed into the southern tip of Sri Lanka.

"The front of the tsunami was on the east coast. It took a turn at the southern tip and the waves start bending at the edges," Fernando said.

Another wave was reflected from India's coast or the Maldives, they said.

In Hikkaduwa, the tsunami rose to a height of about seven to 10 feet, washed inland about 164 feet, with no deaths. The area has rock reefs and its hotel strip has coral reefs.

"The hoteliers were adding seed coral to let them grow for the tourists in glass-bottom boats," said Fernando, who is from Moratuwa, on Sri Lanka's western coast.

From Hikkaduwa north to Akuralla, where residents reported extensive coral damage, the toll on people and property was extensive. A 33-foot wave roared a mile inland at Peraliya, sweeping a train aside and causing about 1,700 deaths.

"Last year when I was visiting I saw this" coral removal, Fernando said. "This time I went and talked to people from the area. It's like a cottage industry."

"They put dynamite and blow them up and get coral and fish," Fernando said. The coral is used in making paint and sold to collectors and merchants who sell it to tourists, he said.

The damage in the area was unrelated to coastline features such as headlands and river channels, the scientists wrote.

Funding for the research came from the British Broadcasting Corp., which filmed a documentary called "Tsunami: Anatomy of a Disaster;" the National Science Foundation, the Earthquake Engineering Institute and the U.S. Geological Survey.