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Save Cruise Ship Ports!!
On August 28, 2016 the Carnival Vista cruise ship’s wake caused over $200,000 in damage leaving the Marina del Nettuno in Italy. I estimate the ship, traveling at 6mph would displace about 1200 cubic meters of water per second per side. If the cruise ship would pump one cubic meter of air per second on the port side of the ship at a depth of 10 meters, the wake would be rendered impotent. The math is simple and is based on the fact that bubbles displace and are displaced by water as they rise to the surface. Also, since it takes a bubble 30 seconds to rise to the surface, there will always be 30 cubic meters of air in the water at any given moment. For further discussion contact me at [email protected]. Thanks! John LeRoux
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January 30, 2018 On the evening of January 22 a 7.9 magnitude earthquake occurred over 2000 miles north of the Islands. A tsunami warning, something of a figurative wake up call, was issued. Most of us literally slept through it. We have made great strides in initiating evacuations in the event of a tsunami threat. On the other hand, our strategy for protecting property from damage is the same all around the world: First—hope there is not a tsunami. Japan has a “Plan B” in case hope doesn’t work. They’re spending billions on seawalls. Sadly, the track record of the seawalls already in place when the 2011 tsunami struck was not impressive. Seawalls wouldn’t be ideal here. I believe large concrete walls between our resort hotels and the ocean could be detrimental to tourism. I suggest the people of Hawaii adopt a “Plan B” of our own. We know that a tsunami wave is merely energy being transferred efficiently through the water. If we could disrupt the efficiency of that energy transfer anywhere in the tsunami’s path, we would end up with a much smaller wave as it reaches our shore. I believe that releasing air into the wave from near the ocean floor is one way to weaken a tsunami. The amount of energy required to create a tsunami wave is enormous, but it is not infinite. The amount of air in a tiny bubble is small, but it is not infinitesimal. When the energy flowing from an earthquake to our islands encounters a bubble, a tiny bit of wave energy is lost. That energy is expended pushing the bubble up and out of the way. That same bubble then robs another bit of the wave’s energy as it rises toward the surface, and so on. I’ve calculated that a 1 cubic centimeter bubble displaces, and is then displaced, by 42 cubic centimeters of water in the first second of its journey upward. As this bubble moves up from the depths it grows larger and moves faster, so the multiple of water displaced increases. It turns out that 1600 cubic meters of compressed air released at 500 meters of depth would knock 10 meters off the top of a tsunami wave heading toward a mile wide section of beach. More significantly, if an infrastructure had existed to pump air into the deep ocean shortly after a dangerous earthquake had been detected, over 270,000 lives could have been saved in the 2004 and 2011 tsunamis. I came up with these numbers using a calculator, a few well known math formulas and a spreadsheet. In fact, though, there are as many ways to stop a tsunami as their are recipes to make a meal. Once you start thinking about tsunamis, or storm surges for that matter, it’s difficult to let it go. A method of stopping tsunamis at sea is so superior to a large fixed structure on the shore that it’s surprising it hasn’t been tried. We all know what happens when air gets into a garden hose. Most of us know what happens when air invades the fluid reservoir of a piece of hydraulic machinery. Skeptics of this approach can see for themselves how many pulls of a spray bottle’s trigger it takes to expel 4 ounces. Next, try the same thing with soda water. You’ll find that the less than 1% of gas in the soda water (by weight or volume) decreases the efficiency of the energy being used to spray the water by over 20%. It’s hard to imagine any plumbing or hydraulic system that wouldn’t become less efficient when you put air in the pipes. Let’s continue to hope there is never another tsunami, here or anywhere, and be grateful that we have a wonderful early warning system. But I believe in this “Plan B” and would love to hear from those interested in this idea. I’d especially like to hear from anyone who believes this idea doesn’t hold water (pardon the pun)! I can be reached at [email protected].
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Seawalls are a waste of money
A 3 cubic millimeter bubble is displaced by 111 times its volume per second by water. A cubic meter of air divided into 3 cubic mm bubbles would be displaced by 111 cubic meters of water per second as those bubbles headed toward the surface. As bubbles rise they speed up and grow larger, increasing that multiple. The forward energy of a tsunami wave would be diminished severely by a relatively small amount of pressurized air released into the water!
I’m available to speak on this topic, or I’m happy to respond to email inquiries.
John LeRoux 1/8/2017
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9 Cubic Meters of Air=1 Seawall
First, think of a bubble of air at 500 meters of depth. It absorbs its size worth of energy every centimeter as it rises to the surface. Another name for a liter is 1000 cc’s. There are 1000 liters in a cubic meter. We’re talking 9 million cubic centimeter bubbles, each one growing and speeding up as it ascends!
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DIY Tsunami Mitigation 12/21/17
If you’d like to protect 100 meters of shoreline from a 10 meter tall tsunami you can do so with a high pressure scuba tank. If you have 1 tank every 100 meters you can protect an entire city. If anyone is interested in the math, contact me, John LeRoux at [email protected]. Hint: I presume a bubble rising to the surface is displacing water in a manner similar to a wave moving forward. More details to come, or see my book: Wave Goodbye--Simple Tsunami Mitigation
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A New Industry is Born! 12-15-17
I am so certain that compressed air can stop tsunamis and storm surges, which will render seawalls obsolete, that I will soon be performing a wave tank experiment at the largest facility I can afford. If you know an insurance risk analyst, a compressor manufacturer, a seaside homeowner or an unfocused thesis writer, please have that person write me at [email protected]. I’ll return all emails (even nasty, clever ones) and am willing to speak anywhere in the US for a fee! I’m especially eager to hear from people who believe tsunamis can’t be stopped--and who know why!
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Stop Tsunamis Without Seawalls
How to Stop Tsunamis and Storm Surges—Math Free Version!
All of the conclusions of this article are supported by math done by me. If you’re interested in any of the underlying calculations, email me at [email protected]. Thanks! John LeRoux
A tsunami wave, or any ocean wave, is energy moving through the water. Water moves forward and backward, up and down, like the piston rod of a steam locomotive. Water remains in the same position relative to the ocean as the wave moves on. The piston stays in the same position relative to the locomotive as the train moves on. If we can weaken or shrink the water’s (or the piston’s) movement, we can weaken the wave or slow the train.
A tsunami wave’s duration is 18 minutes. It travels faster with a larger wavelength in deep water, and slower in shallow water. Once a tsunami gets started it takes very little energy to turn it into a chain of 3,4,5 or more waves traveling through the ocean. The earthquake (usually) that started the tsunami provided all of the energy the wave or waves are ever going to get. A tsunami wave demonstrates a highly efficient conservation of energy, but it cannot gain energy.
Here’s how a tsunami works: First, remember that any water rising toward a crest had to come from an equal volume of trough. The energy of the moving water, initiated by an earthquake, pushes water up and forward. Let’s call a drop of water sitting on the surface “Bob.” When the leading edge of the wave reaches “Bob” he gets pushed forward and up and becomes part of the moving wave. When the crest of the wave reaches the point that “Bob” now occupies, he and his neighbors begin falling down and back to his original home. This falling pushes the wave forward with almost no loss of energy.
It’s important to realize that the water moves very slowly, and the energy moves very quickly. It’s analogous to a garden hose full of water. When you turn on the tap, the water might flow out at 3 MPH. The water at the end of a 300 yard long hose might start coming out within seconds….
That’s the principle of tsunamis!
…..unless there is air in the hose!
That’s the principle of tsunami mitigation!
If you can release air into the oncoming wave at a depth of 300 meters or more, you can de-energize a tsunami completely. A total of 30 cubic meters of compressed air released deep in the water ahead of a tsunami will do the work of 1 mile of seawall. It can be released in one spot, or divided among several locations and the effect will be the same.
This protocol is better than seawalls for obvious reasons, such as being less obtrusive and somewhat portable. It is also better than a seawall because it takes the energy of a wave off the top, in other words it can turn a 15 meter wave into a 5 meter wave. A 10 meter tall seawall is worse than useless in stopping a 15 meter tall wave.
I’m happy to speak to any group in the USA on this topic. If you own a beachfront property, are looking for a thesis topic, have an interest in civil defense or insurance risk analysis, please write. My book is called “Wave Goodbye—Simple Tsunami Mitigation.” I believe this is the first hint of an entire new industry—Tsunami Mitigation!
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This book explains how to stop tsunamis
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How to stop a tsunami 11/26/17
How much gas has to be dropped ahead of a tsunami wave to render it impotent? Relatively, not that much. If 100,000 extra cubic meters of energy are pushing through our 10 meter wide example, and it takes 1000 seconds for this wave to pass, the crest part will take 500 seconds. This means 200 cubic meters will be pushing through a point every second. If you released a 22.5 cubic meter balloon at the bottom of the sea into the wave it would be displaced by 10 to 40 cubic meters of falling water per second (depending on the speed of the ascent). This means that the wave would be weakened by 5% to 20% through the portion passing the rising balloon. If the balloon is released during the trough part of the wave it will decrease the speed of the propelling falling water, and thus weaken the wave. It’s easy to imagine that water on the far side of the balloon will have less pressure than the water elsewhere in the wave.
Releasing air instead of water ahead of a wave will be even more efficient at mitigating the energy than a balloon. Air in a balloon can be compressed by deep water, but free air cannot.
Another factor that must be considered is that gas expands as it rises. The most critical part of a tsunami is the portion being pushed above, or dropped below, the surface. This is the area where our added gas is at its largest volume.
Finally, if the gas breaks the surface in a tumultuous manner, it will bring a large amount of water upward out of the ocean. Typically, when this water falls back to the surface it brings more air with it than was in the water to begin with. The breaking part of the wave spills ahead and splashes into the water just ahead of the leading edge of the wave. This foam then becomes part of the wave as the energy catches up. This new part of the wave is terrible at pushing water forward. It’s so light compared to the foam-free water pushing it that it gets thrown ahead, bringing more foamy water into the oncoming wave. When a wave breaks the foam doesn’t disappear, it spreads. This means that artificially breaking the wave, well out to sea, can weaken it to nothing before it ever gets near a beach.
How much of a tsunami wave could be weakened by 500 liters of liquid nitrogen? Since 1 liter turns into about 2/3 of a cubic meter of gas at sea level, 500 liters would be 333 cubic meters. If we presume we can keep 300 cubic meters of gas in the water for the entire 18 minutes of the wave we can make a serious dent in a tsunami.
Let’s say we release 500 liters of liquid nitrogen ahead of a wave that is similar to our example. It’s now 1 meter high, and carrying 200 cubic meters of energy per 10 meter section, per second. If the nitrogen bubbles are 1 centimeter in diameter, they will rise at over 3 meters per second. Over a 1 kilometer section of wave, the incoming energy will be 20,000 cubic meters per second, while the water falling into and displacing the bubbles will be 900 meters per second.
This example works at any point in the wave, but let’s consider if this wave hits the rising nitrogen bubbles at the nadir of its trough. The energy which was lifting the surface of the water by 2 meters from trough to crest is now 4.5% weaker. Therefore, the wave crest will be 9 centimeters lower. The momentum of the water falling will be weakened by 4.5%. This wave will have been weakened by over 17% trough to trough, as the new trough is only 82.81 centimeters below sea level.
If another boat dropped another 500 liters of liquid nitrogen in front of this wave 1 kilometer closer to the shore, the gas would be approached by a weaker wave. Instead of moving water at 200 cubic meters per second it would be moving at 166 cubic meters per second. 900 cubic meters of falling water would take 5.4% of the remaining energy away. The new crest would be 73.8 centimeters and the new trough would be 65.8 centimeters below sea level.
This analysis doesn’t take the breaking of the wave into account. If it could, the result of the gas addition would be even more impressive!
If you have any thought on this arithmetic, or if you know anyone who would like to discuss this idea, please write me, John LeRoux at [email protected]. If I ever get an email I’ll write back!!
#tsunami#seawall#disaster mitigation#storm surge#Fukashima#Tsunami evacuation#liquid nitrogen#coastal flooding#wave goodbye#tidal wave
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A bit better tsunami sample
In yesterday’s theoretical tsunami, created in a 4000 meter deep channel, the estimated wave height should be 18 centimeters. I used the wrong numerator yesterday and estimated 1.8 meters. I arrived at that figure by distributing the 100,000 cubic meters of additional water on the crest side of the wave over its 10 meter width, 106.5 kilometer breadth (half its wavelength) and 4000 meter depth. The result was the average height of this wave would be 9.8 centimeters, so the top of the curve would be around 18 centimeters.
If the channel were cut in half to 5 meters the wave would obviously double to 36 centimeters at its crest. This type of thing happens when the mouth of the bay is much larger than the waterfront, such as in Hilo, Hawaii.
If instead the depth of the water lessened to just 200 meters the wavelength would shrink to 48 kilometers. Distributing the same 100,000 cubic meters of additional water to this more compact wave would result in a height of 41.7 centimeters over sea level, or a wave height of 80 centimeters.
At a depth of 50 meters the wavelength is 23 kilometers. The average height is 87 centimeters higher and the wave is 1.6 meters.
At 5 meters of depth the wavelength is 7.6 kilometers, the average height is 2.63 meters over sea level, and the wave height is 5 meters above the surface.
It’s impossible to say what the wave height would be at the shoreline, as there would be too many extra variables despite the precise measurements of the example. There is, however, a maximum amount of water that can make it up to land in this exercise. That figure is 100,000 cubic meters. That number represents the same amount of water that was displaced in the first place. There is no mechanism for a wave to gain energy by merely traveling through the ocean. If this wave retained its 10 meter width it could produce a wedge of water on land 10 meters high and 2,000 meters inland. Structures existing in that “flood plain” would allow the water to travel further inland.
This is the worst possible scenario for this wave.
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A description of tsunamis
Today I’m going to create a sample tsunami wave with words, and show how it can be stopped!
Suppose you had a 10 meter wide channel filled with seawater. Let’s say it’s 4000 meters deep and the length is many thousands of kilometers. You can start a wave in this channel by moving water, preferably at the closed end. One hundred thousand cubic meters of material added to this end of the channel would displace one hundred thousand cubic meters of water already sitting there. You could accomplish similar waves by dropping a column of concrete 5 meters by 5 meters by 4000 meters, or several smaller columns with the same total volume. It would have to displace that water quickly to make a wave.
If this displacement became a tsunami wave, and in this case it certainly would, this wave would travel at 713 kilometers per hour, and the wavelength would be 213 kilometers.
The simplest way to conceptualize our sample is to think of it like this: All of the water in the first 2.5 meters of channel simply moved over by 2.5 meters. If it took 1 second to get out of the way of the incoming disruption each drop of water moved at 9 kilometers an hour. Since there was already water in that position, that water had to move 2.5 meters to get out of the way. And so on. It’s easy but wrong to conclude that every for 10 kilometers of wave travel 400 million cubic meters of water are displaced. That conclusion can be defended arithmetically but is not practically valuable, as after the wave passes, every drop of water is roughly back to the spot it occupied before the wave passed through.
In this example, the water that started moving at 9 kilometers an hour when the wave was formed by a 1 second event, has pushed water ahead at the speed of 1 kilometer per hour while the wave is moving at 713 kilometers an hour. Remember the initial movement lasted just 1 second, but it took an incredible amount of energy to move 100,000 cubic meters of water 2.5 meters. Once the wave gets started it is highly efficient in conserving that energy. If this wave is 100% efficient it will be able to move 100,000 cubic meters of water indefinitely.
However, the water being moved is taking a short round trip. The original movement of water was 2.5 meters. As long as the depth of the ocean remains at 4000 meters, that 2.5 meters is as much lateral movement as a drop of water is going to get. Furthermore, since there is no net movement of water by the wave, that drop of water will move back 2.5 meters after the wave crest passes, leaving it essentially where it started.
Here’s how it works: The leading edge of a tsunami wave reaches a given point in our channel. This wave is traveling at 713 kilometers an hour and it moving along the entire depth of our sample channel. It still contains enough energy to move 100,000 cubic meters of water 2.5 meters. The crest of this wave is being formed by water being pushed forward at 1 kilometer per hour. The crest portion of the wave is half the wavelength, or 106.5 kilometers. The energy in this example is enough to create a gentle, large wave reaching 1.8 meters over mean sea level at its crest. The trough portion of the wave is the inverse of the crest. If a drop or a gallon of water is moving forward in the ocean at 1 kilometer an hour, it’s pushing water already there forward. That “push” travels at 713 kilometers per hour. When the leading edge of the “push” reaches a given point in the ocean it starts to crowd the water already there. A drop of water sitting on the surface will be nudged forward by the incoming wave. For the first 4.5 minutes of this tsunami’s journey that drop of water will be pushed forward 2.5 meters and up nearly 2 meters as it becomes part of the wave’s crest. Since there is no loss of energy and no net movement of water this single drop will join its neighbors in falling down and back after reaching the crest. It will move back 5 meters and fall nearly 4 meters in the next 9 minutes and end up at the nadir of the trough. This forward and back movement is neutral when looking at crest to crest or trough to trough of a group of waves.
The energy that was needed to lift 100,000 cubic meters of water up and ahead is retained as that mass falls down the back side of the wave, propelling it forward.
Spoiler alert: Tomorrow I’ll talk about the problems caused by tsunamis. Hint: What if the depth of water decreases?
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Hurricane Mitigation
11/16/2017 A brief digression. Hurricanes can be weakened by pumping water from the chilly deep ocean into the area of sea energizing the storm. This technique would be particularly effective if used on the south side of a Northern Hemisphere tropical depression. Cooling the ocean surface to < 79 (F) over 3% of its energy source would diminish the rotation. Covering 75 square miles of ocean surface with 1 inch of cold water would take the amount of water displaced by 25 cruise ships. If you’d like to discuss the math write me at [email protected]. Thanks for reading!
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Tsunami Post # 11
“The Butterfly Effect” is a theory which is used as a metaphor in science. It says a small variation in the initial stages of a process can result in huge changes at the end. For example, take the 50th route of 50 billion, round that number to 10 digits after the decimal point and raise that to the 50th power. You’ll end up with 50 billion plus 55 or so. The reason the theory refers to butterflies is the belief that a random butterfly’s wing flap can set in motion a chain of events that eventually creates a tornado. Rather than hunting down suspicious butterflies, I suggest we look at this theory as an encouragement for us to disrupt an unwanted process well after it starts. And to interfere with something a bit more substantial than the flapping of an insect’s wings. Of course I’m talking about putting air in the path of a tsunami. When you see air start to show up in a wave the air never gets overwhelmed by the smooth, air-free part of the wave. Rather, the white water of the wave break spreads and the energy of the wave dissipates quickly. It’s conceivable that this small weakening of a tsunami can be the key to turning a potential disaster into an annoyance.
Perhaps you believe that “The Butterfly Effect” is rubbish and not worth a moment of your time. I would agree with that, if we’re talking about the movie!
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CO2 and the Preservation of the Race
The race I’m talking about is the Escape From Alcatraz Triathlon. On June 11, 2017 the swim portion of this race was cancelled, due to rough water. You can’t really have an Escape From Alcatraz without the escape from Alcatraz. if a dozen large CO2 canisters had been opened up and the gas released in the waters near Alcatraz Island, any incoming waves would have broken there. This would have allowed the rest of the bay to remain somewhat calmer.
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Tsunami Post # 9
I goofed yesterday! The figure of 6.2 mm was the radius of the rising 1 cc bubble. The diameter was around 1.25 cm. -- I feel like I’ve not painted a clear picture of a tsunami wave. How’s this?: You have a large hose or pipe full of water. Let’s say the capacity of that pipe or hose is 10 liters per 1/2 meter of length. You then spend 9 minutes trying to force 50 more liters into one end of the hose or pipe. That additional water will move 2.5 meters into the hose (pipe) and will force the water already there to move forward. If the energy is moving at yesterday’s 713 km per hour, the first indication that something is happening in that pipe will be felt 107 km down the line after 9 minutes. If there are, say 60 liters of air in that pipe/hose anywhere along that 107 km of line, the energy will stop there. No water will be moved past the air bubble, no mater how long the hose/pipe is. In a tsunami wave more than just one “pipeline” of energy can be stopped with air. Consider a situation where, as soon as the air stops one pipeline’s energy, that air moves to an identical pipeline just above it. If the interior diameter of this hose/pipe were 64 cm this magical transfer of air from pipe to pipe would occur 6250 times in a 4000 meter stack of pipes. Since these pipes have a diameter of 64 cm there would be 156,250 stacks of pipes covering a 100 km lateral swath of ocean. These means that 9,375 cubic meters of compressed air released at the ocean floor would’ve defended 100 kilometers of Indonesian coastline, even without considering the fact that air expands as it rises in water!
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Tsunami Post #8
400 million kilograms of air is a lot. In truth, it would be worth it to stop a tsunami. Actually the amount of air necessary to stop a tsunami would be a small fraction of that. At 4000 meters of depth a 2004 sized tsunami would move water molecules forward 2.5 meters in 9 minutes, once the wave was established. After 9 minutes the molecules that were first moved 9 minutes earlier will be at the peak of the wave. For the next 9 minutes those molecules will fall back to their original position. The water is moving slowly but the wave is moving at 713 km per hour. A 1 cc bubble of compressed air released at the ocean floor will be displaced by 1 cc of water. Since this bubble’s diameter is around 6.2 mm this process will be repeated over 645,000 times before that bubble reaches the surface. By the time that bubble reaches 10 meters of depth it will have grown to 200 cc’s with a diameter of 3.6 centimeters. The rising bubbles’ water displacement is competing with the 2.5 meters per 9 minutes of water molecule movement, not the speed of the wave. Since the bubble has no forward bias as it rises, the water displaced by bubbles subtracts energy from the wave.
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Tsunami Post #7
To quote zen master Shunryo Suzuki, "In the beginner's mind there are many possibilities, but in the expert's there are few." Suppose we wanted to protect 10 km of beach from an Indian Ocean sized tsunami. A 100% efficient wave would contain enough energy to lift just under .1 cubic kilometers of water onto the shore. A 35 by 2 meter seawall would contain 700,000 cubic meters of concrete and weigh over 1 and 2/3 billion kg. A .1 cu km bubble would absorb all of the energy of that wave if placed anywhere in the 10 km swath of ocean between the quake and the shore. This same result would be obtained with many bubbles totaling .1 cu km in aggregate volume. Since compressed air weighs around 4 grams per liter, a cubic meter would weigh 4 kg. This means that the absolute top end estimate of the amount of air necessary to completely neutralize a strong tsunami heading toward a shore is 400,000,000 kg by weight, less than 1/4th of the weight of concrete necessary.
But wait there’s more!
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