Cobb: An Ex-Bodysurfer's View of the Tsunami

January 01, 2005

An Ex-Bodysurfer's View of the Tsunami

Now that I've eyeballed several of the tsunami videos, I have to say a few things.

As a native Californian body surfer, I'd say that none of those waves looked extraordinarily high. The one that did show a big break looked to be about 8-10 foot as far as I could tell. That's a big wave, but not a huge wave. At my peak, an 8 footer was about all I could handle. Six footers I could handle for an hour or so and then I'd be exhausted, but there are a huge number of variables, most importantly the shape of the beach. The reason I mention this is that if I were on the beach and I was surprised by a good sized wave, my instinct is to swim towards it.

This is not just a gung ho thrillseeker attitude, it's the way to survive. The massive force of the wave is in the break. If you stand still, the whitewater is going to knock you over, there's no way around that. But if you get behind the wave, you're a lot safer.

I don't know exactly how a tsunami wave is different than a storm wave coming in, and I am not trying to downplay the force of any wave. But if there's going to be a 10 foot swell and you're on the beach, get into the water. There's no way you can tell if there's going to be shrapnel in the water when you make your decision so you'd have to depend on instinct. Sooner or later you're going to have to swim out. But I'd much rather be in the deep water offshore than in the shallow water where all kinds of lumber and glass is in the current.

On the other hand, I've heard accounts where folks said that the beach receded about 3/4 of a mile. When I heard that people were going down where the water used to be and picking up fish I was kind of astounded. Didn't they figure out that the water was going to come back? But that would be consistent with what I saw in the Phuket video which looked like a very shallow profile. Phuket would be mush all day, no breaking waves. So when the tsunami did come in, it would look like a broad band of whitewater instead of a cresting wave. The break didn't look as if it were travelling much faster than ordinary storm waves either.

The most dangerous scenario I can imagine would be where the beach has a medium rise, no seawall of any sort and then drops down onto relatively hard ground with small buildings. If as you go inland, the elevation drops even slightly below sea level, all that flotsam would go rushing fast. I've heard tell of a 30 to 50 foot rise in the ocean. Three or four sets of 8 to 10 foot waves on a tide that rises 50 feet in an hour would make a huge mess. So when I saw pictures of scores of dead bodies floating in broken lumber, I knew just what kind of mess that could be.

I fear drowning more than just about anything, and I was a pretty decent swimmer. I used to bodysurf all day long back in the day, and was a certified Junior Guard. That's the 'highschool' of California beach lifeguarding, so I know a little something about reading the shore. What's very tragic about a lot of these deaths is that I'm sure a lot of them were caused by people getting caught in the break and then twisting ankles and breaking legs trying to get away. When you're running in water and don't know what the bottom is like, that's sure to happen, especially if you're panicked. Even 3 foot mush will knock a strong man over. If you're on concrete, you're screwed.

In confined spaces, the situation would be more like whitewater on a river. Five feet of water falling 10 feet, like down a short flight of stairs, could be absolutely deadly. People caught in the doorway to a basement or the driveway to an underground parking structure would surely be in trouble. Add the random piece of furniture or tree branch; yike.

Posted by mbowen at January 1, 2005 10:54 PM

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Comments

The main difference between tsunami and run-of-the-mill waves is not, contrary to the popular '70s disaster flick image, wave height but rather length, so to speak. The sheer distance between the troughs means that the wave just keeps coming and coming, long past the shore's ability to shunt it off. With nowhere else to go, the water comes rushing in. Just imagine someone suddenly turning on a high-current river flowing through town. Then the river flows the other way. Do it a couple of times and it seriously compromises the structural integrity of most buildings.

Posted by: submandave at January 3, 2005 02:25 PM

That's true. Looking at the waves at Sri Lanka, particularly the video taken by the Aussies from the top floor of a hotel overlooking the courtyard, I could see that those were a couple of pretty quick sets. The water level rose very quickly as the break from the second wave came over before the first had receded. That would have been the unusual part about riding that wave -- the 'shore' never comes.

Posted by: Cobb at January 3, 2005 09:44 PM