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Daily Astorian -
The tsunami two years ago in American Samoa has given scientists a chance to examine an issue that often seems of little significance in the immediate aftermath of these massive disasters; the little-seen, rarely studied but often frightening damage done to offshore coral reefs.
A new study by scientists from Oregon and Michigan, done with a remotely operated undersea vehicle (ROV) surveyed large areas of that area's coral reefs, and revealed significant damage from sediment, debris, and the enormous forces of both the incoming and outgoing waves.
Corals are delicate living organisms that can only survive in shallow, nearshore areas where they get adequate sunlight.
That's also where the tsunami wave action is most violent, and they are especially vulnerable to its impacts; but often ignored in the understandable concern about terrestrial damage and loss of life.
"Very little until now has been known about the impact of tsunamis on coral reefs," said Solomon Yim, a professor of structural and ocean engineering at Oregon State University and co-author of the study, which was supported by the National Science Foundation.
"These are huge forces and often these events have happened in remote locations of the world where we had little opportunity to study them," Yim said. "American Samoa gave us the chance to use some very sophisticated equipment to gain a much better understanding of what damage is being done to coral reefs, and what might be done in the future to help reduce it."
On Sept. 29, 2009, a magnitude 8.3 subduction zone earthquake near American Samoa sent waves crashing into many islands, destroying buildings and eroding coastlines with waves up to 20 feet high that came almost a mile inland and killed more than 180 people.
It was the world's largest earthquake that year. The onshore devastation was heavy. Although not seen at the time, so was the underwater damage to coral reefs.
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