Imagine a massive earthquake under the ocean, triggered by the movement of tectonic plates along the Pacific Rim. It creates huge waves that travel at high speed towards the shores of many countries. People are unaware of the danger, going on with their lives, as the deadly tsunami approaches.
From a bird’s eye view, we see the waves spreading across the water towards land. A faint glow appears on the horizon. It is a force field that protects the coast from the impact. The tsunami hits the barrier and loses all its power, leaving the land unharmed.
This might be a scene from a sci-fi movie, where humanity has found a way to defend itself from natural disasters. But what can we do in reality to protect our coastal areas from such threats?
This is how I came up with the idea of the Tsunami Diffusion Array (TDA). I was sitting on a beach near Malibu, California, watching the waves crash on the rocks. The tide was rising. I looked down for a moment and when I looked up again, I saw a big wave coming towards me. It seemed like it would soak me. I tensed up, but nothing happened.
The wave had broken over a rock formation that was much smaller than the wave itself. It had dispersed the wave’s energy so much that it barely reached my feet. I was intrigued.
I examined the rock formation more closely and realized what was going on: it was a natural diffuser. The rock had been eroded by the water over time, forming five rows of columns that were offset from each other. Each column had a rough triangular shape, pointing towards the ocean like an arrowhead. They were perhaps made of different materials that wore off at different rates.
The rock formation acted as a perfect device to split and redirect the wave into itself. The columns in each row cut the water flow into smaller streams. Each stream was angled towards the next one, creating a collision that reduced the wave’s energy. The remaining water flow continued to the next row of columns, repeating the process.
The rock formation was much smaller than the wave, but it still managed to weaken it a lot. The wave was not curling, but flat, like a small wall of water. It had a lot of energy, but it was absorbed by the effects of the rocks. The water was about two feet deep, and the rocks were about one and a half feet above the resting waterline. The wave was about three feet high and moved at about 12-15 mph. The rocks stopped the wave in less than 13 feet, with some help from the slope of the shore.
The TDA would have to be adapted to different conditions, such as the shape and size of the sea floor, the tides, the wildlife, the shipping routes, and the area to be protected. But the basic idea and structure would be the same: a series of “channeling towers” that would split and redirect the waves. The towers would be arranged in rows that were staggered from each other. The whole array would form a slight curve that would face the sea. The curve can be seen from above in Figure 2 below. The location and shape of the array might vary.
The channeling towers could be about half as tall as the waves they are meant to stop. But this might change with more research and better design. The tower would look like a wedge pointing out to sea. The pointy end would split the water flow. The round backside would reduce wind drag. The angle of the wedge would depend on how the water should be redirected, and how strong the tower should be to resist the wave. The edge of the tower could be shaped to improve water flow. The top of the tower could have different forms to make it more aerodynamic. It could be a dome or a fin.
In an ideal scenario, one that would need a lot of technological progress, the array would be able to hide under the water or the sea floor. It would be made of very strong nanomaterials that could extend and retract like an antenna, and have guaranteed strength to no break or loosen from the sea floor. Maybe the array would be activated by early warning systems that detect earthquakes. Maybe each tower would move using magnets and electricity. Maybe there would be underwater power sources that use heat from the earth’s crust. These are some of the possibilities for the future. But we can also build something that works now, even if it is not as fancy.
A TDA that could be built now would probably be made of concrete and metal and fixed in place. This would still be better than building walls or oversized breakwaters to protect the coast. Those are not always possible or effective. A TDA would use less materials and have less impact on the coast. Though it would be imperative to make sure the structure could withstand massive force to avoid coming loose and launching with the wave inland to devastating results.
I also thought about how the TDA would affect the coast and its life forms. How would it change the tide and the creatures that depend on it. In a futuristic version with towers that can move up and down, this might not be a problem. But with a permanent TDA, we would have to do more research and planning.
If the TDA is too close to the shore, it could harm the tidal life. But we could find ways to avoid this, like making openings for fish to swim through. The towers could also be designed to only stop waves that are higher than normal. Underwater, they could let the water flow more freely. It might also be possible to put the TDA farther from the shore, where the sea floor is deeper. This way, it could still stop the tsunami waves without affecting the regular tides.
We would also have to think about how the TDA would affect the public and the businesses. Would people like to see the array near the shore? This would depend on how the TDA is built. For example, how far from the shore and how close to each other the towers are. They could also be painted to blend in with the sky and the water. The TDA could be designed to use as few towers as possible.
What about the ships that need to pass through? If the TDA is too big to go around, maybe there could be a wider gap in the array that is angled. This could let the ships go through safely, without reducing the TDA’s ability to stop the waves.
The TDA could also have other functions. It might be a good place to generate wind or tidal power. The tsunami could damage this equipment, but it might still be worth it in the long run. The towers could also be used for communication, radar, observation, or even defensive weapons.
Like many inventions, the TDA would have pros and cons. It would need a lot of research and planning. It would also depend on the resources and technology we have. Many questions would come up. How much do we need it versus how much does it cost? How would it affect the people and the environment? How big a coast could the TDA cover?
The TDA is a proposed device that could reduce the impact of fast tsunamis by diffusing their motion energy. However, it would not be effective against slow tsunamis that have more kinetic energy. To protect against those, the TDA might need additional features that could absorb the force of the wave. The TDA could still save many lives and properties from fast tsunamis, which are more common and unpredictable.
In concluding, the Tsunami Defense Array is a concept that could potentially save millions of lives and billions of dollars from the threat of tsunamis. It is inspired by a natural phenomenon that I observed on a beach. It is based on the idea of using channeling towers to split and redirect the waves before they reach the shore. The TDA would have to be adapted to different conditions and locations, and it would have to balance the benefits and the drawbacks. It would also have to consider the impact on the public and the environment, and the possible alternative uses of the towers. The TDA is not a reality yet, but it could be one day, if we have enough motivation and innovation.
Illustration by Lorenza Cecconi