Opus Tsunami 3 - Science

The science behind tsunamis, from my book "Opus Tsunami." You're receiving the entire book free, chapter by chapter, because you're a valued subscriber!

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Science

Never trust a tsunami, no matter how small it looks. Far too many people rush to the shore to see one for themselves when they learn that there’s tsunami inbound.

For example, following the 2011 tsunami which shattered Japan, thousands of people in Hawaii, California, and Australia flocked to the coastline to catch a glimpse of that same tsunami. Luckily it was small enough by the time it reached North America that most people were safe, although there was at least one death in California. These people didn’t heed warnings. They wanted to film it. They wanted to see it for themselves. But if there’s one natural disaster that people should stay away from, it’s a tsunami.

That’s because tsunamis are one of the most destructive forces of nature on the planet, and it all stems from the way they’re born, how they move, and what happens when they hit land. Those who understand the mechanics behind a tsunami know to get away as soon as possible. 

For starters, tsunamis are not regular waves. Regular waves are caused by a combination of wind and tide, which means it’s only the surface of the water which is moving. In fact, despite appearances, in a regular wave, the water itself is barely moving. Instead, the molecules that make up water are transferring energy from one column of water to another, which is why waves often appear to be standing still on the surface of the water. Think of a game of telephone: the message is going from one person to the next, but the people themselves aren’t moving. That energy ripples through the surface of the water and breaks on the shore when gravity pulls the crest of the leading waves down. This is how regular wind-driven waves work.

Not so with tsunamis. 

Another mistake people make is to call tsunamis “tidal waves” but this is a misnomer, as tidal waves are simply larger normal waves. They’re big, but they don’t pack much of a punch. A tsunami is an entirely different beast. 

Tsunamis consist of the entire body of water lurching forward at high speed. In this case, the water is moving. All of it. From the surface of the water to the bottom of the ocean floor. This phenomenon is a result of a massive displacement of the water. In the case of the 2004 Indian Ocean tsunami, the seabed suddenly reared up by over 60 feet when the subduction zone snapped. The result was that all of the water above was violently pushed up and away, creating one of the biggest tsunamis in recorded history. But other seismic events can cause a tsunami as well. The US Tsunami Warning Center writes 

“Large earthquakes below or near the ocean floor are the most common cause, but landslides, volcanic activity, certain types of weather, and near earth objects (e.g., asteroids, comets) can also cause tsunamis.” (National Weather Service - Tsunami Warning Center)

There are lots of things that can cause a tsunami. While earthquakes cause the majority of them, landslides have been known to create monster tsunamis as well. For example, in 1958 a small earthquake rocked Lituya Bay, Alaska. This earthquake caused part of a mountain to collapse into the coastal bay. The result was a mega-tsunami that reached 1700 feet (524 meters) in height. This wave was taller than the Empire State Building in New York City. 

It ravaged the coastline of the bay, tearing away the sides of hills and mountains. Thankfully the bay was uninhabited by people, and there were only two deaths. One witness, a local fisherman named Howard Ulrich who was boating with his eight-year-old son at the time, saw the wall of water rise up in front of them. He said 

“It was a mountain of water, filled with logs, coming right at us.”