Magazine / People

Interview: Author Dennis Powers on tsunamis

"One estimate is that there’s a 50 percent chance of a major eruption off the U.S. West Coast in the next 50 years," says alumnus and tsunami expert Dennis Powers. Photo courtesy of Dennis Powers

Dennis Powers (JD ’66) grew up near the New Jersey shore, where he sailed, surfed, water-skied, kayaked and fished. He has channeled his love of the sea to pen five maritime books. His first, The Raging Sea (Citadel, 2005), was about the devastating 1964 tsunami that crashed down the West Coast and centered in Crescent City, Calif.

 

Q: What happened in the 1964 tsunami?

A: The earthquake was a 9.2 magnitude that ruptured off Alaska at 7:36 p.m. on Good Friday. The tsunami traveled 2,000 miles to center on Crescent City, then traveled around the world twice. The killer wave came in around 1:45 a.m. That one measured 25 feet high and went inland 1½  miles. Thirty city blocks and 289 businesses and homes were destroyed. It smashed into fuel tanks and flamed electrical lines, creating fires that looked like World War II night naval battles. Cars were pummeled, buildings snapped off their foundations. Thirteen people drowned and scores of people were injured.

 

Q: What did you learn about tsunamis in your research?

A: Underwater disturbances — landslides or volcanic eruptions — can cause tsunamis, but most earthquakes don’t. For a destructive tsunami, an earthquake must be severe, it’s got to be offshore and there has to be an up-and-down motion. This creates the ingredients for a truly massive tragedy. That’s exactly what happened in the 2004 Indonesian and 2011 Japanese tsunamis. A tsunami is basically energy that’s flowing through the medium of water. It’s amazing to watch the way the disturbance works around continents. It refracts off underwater obstacles, finds channels — it’s almost like a living, breathing thing.

 

Q: What’s the likelihood that the U.S. will experience another tsunami?

A: The West Coast is part of the “ring of fire” where 80 percent of all earthquakes that can cause tsunamis take place. The Cascadia Subduction Zone fault line lies approximately 50 miles off the West Coast. It ruptures every 300 years or so, and the last one was in 1700. One estimate is that there’s a 50 percent chance of a major eruption off the U.S. West Coast in the next 50 years. National Geographic has stated that if such an event occurred, more than 10 million people would be “adversely affected.”

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