Taking a technical look at the tsunami

Tim Lougheed

The world has become familiar with the images of human toll taken by the tsunami that swept through the Indian Ocean on December 26, 2004, killing in excess of 300,000 people.

	(Top photo) Professor Murat Saatcioglu, right, listens to Thai ambassador Snanchart Devehastin. (Bottom photo) Professor Ioan Nistor gives a technical explanation.

Civil engineering professors Murat Saatcioglu and Ioan Nistor are some of the experts now taking a hard look at the technical dimensions of this catastrophe to determine its implications for other settlements along the world’s coastlines. For two weeks at the end of January, they composed one of the first teams to survey and analyze the structural damage in some of the worst hit parts of Thailand and Indonesia.

On March 16, 2005, Saatcioglu and Nistor provided some of their findings to a packed auditorium, an audience that included Thai ambassador Snanchart Devahastin. Their presentation opened with a comprehensive collection of dramatic amateur and news videos taken in areas where the tsunami struck.

Saatcioglu, who is president of the Canadian Association for Earthquake Engineering, said that much of what he found in Thailand and Indonesia reminded him of other places he has visited in the wake of major seismic events.

Nistor, who specializes in coastal engineering, described the tsunami as a secondary effect, caused by the displacement of a tremendous volume of water when part of the sea floor dropped below another part. The result would have been scarcely detectable to anyone out at sea, where a wave no higher than a metre would have been seen traveling along the surface, although at a speed of hundreds of kilometres an hour. However, once that wave reached shallower water, it grew to daunting proportions, sometimes reaching 10 metres in height as it crashed into some shorelines.

The damage caused by this wave differed significantly from typical earthquake damage. Saatcioglu recalled taking a while to appreciate the profound impact of “debris,” which included objects like automobiles and huge boats that were carried as far as 3.5 km inland, wrecking many buildings in ways that neither water nor an earthquake alone would have done.

In fact, he noted that when the tsunami struck, the resulting pressure on some buildings was much less than that of an earthquake, and properly designed buildings did survive the assault. He saw evidence of this on Phi Phi Island, where the wave swept over. “Even though the entire island was devastated,” he said, “there were a number of hotels that stood up very well.”

Timber-framed dwellings, not unlike most Canadian homes, did not stand up as well, however. Showing a picture of Vancouver situated on low-lying Pacific coastline that differs little from the areas struck by the Indian Ocean tsunami, he suggested that a comparable wave would create the same kind of scarred landscape.

Similarly, he added, the relatively sparsely populated west coast of Vancouver Island would absorb a lot of the impact of any such wave before it reached the city. Also there is a good chance that structures built to withstand earthquakes would hold up to any such tsunami.

“This is something of a wake-up call for all of us,” concluded Saatcioglu.