Tsunamis are unpredictable, and fantastically powerful aquatic disasters. A series of enormous waves blast ashore sweeping away everything and everyone in their path for hundreds of meters.
You can be half a mile from the ocean and still be overtaken, drowned and killed by tsunami waters. Even staying away from the ocean won’t keep you safe; tsunamis can occur in any sufficiently large body of water that undergoes massive displacement, including large lakes and bays.
Surviving a tsunami requires some kind of advance notice, a solid plan and quick action. Waves anywhere from 10 to a hundred feet tall will be assaulting your position on dry land traveling at 25 to 35 miles per hour. There is no time to delay when a tsunami is inbound.
But that isn’t going to be you. Armed with the knowledge contained in this guide you’ll be able to see the signs that indicate a tsunami is imminent and get to safer ground in time.
What is a Tsunami?
Tsunamis are sometimes called tidal waves, and often imagined to be Titanic singular waves hundreds of feet tall. While waves that gargantuan are not completely unheard of, they are atypical of a tsunami.
In fact, tsunamis don’t have anything to do with the tides at all. Instead, tsunamis are a series of waves (called a wave train) that speed towards the shore after a body of water has undergone a massive displacement event. This displacement could be caused by all kinds of things. By far, the most common are undersea earthquakes.
Landslides that take place above or below sea level are also likely culprits, as are volcanic eruptions and even celestial bodies like meteorites, comets or asteroids impacting a large body of water.
Humanity can even get in on causing a little tsunami action by doing something really crazy like detonating a nuclear bomb beneath the sea.
Have you ever thrown a rock into a pond, or dropped your bar of soap in the bathtub? Notice the rings of water that race away from the impact point? That is essentially what a tsunami is, just on a humongous scale.
Compare what forms a tsunami with actual tidal mechanics. Normal ocean tides are affected by wind and the gravitational pull of the moon. They are more or less regular, gentle and predictable.
The tide goes in and out. Up and down. But not tsunamis: tsunamis only travel in one direction and that is up and over, far inland.
This is because the displaced water will be compressed and rise as it nears shore and it has far too much water closing in right behind it for it to slow down, ebb and retreat.
A tsunami, singular, is actually a series of waves, plural. After the initial wave impacts the shore the remainder will follow up and impact in intervals, possibly a few minutes, possibly a few hours.
Each one is extremely dangerous, and the first wave is often not the worst. This can lull victims into a false sense of security. The damage potential of each wave and a tsunami is nothing short of massive.
An unimaginable quantity of water being driven at high speed packs nearly incalculable force and will sweep away any human, cars and even buildings easily.
After the tsunami is finally, truly over, the affected area will be utterly flooded, and survivors will be forced to deal with that in the aftermath.
Tsunami Affected Areas
Tsunamis can affect any land that borders a large body of water and a significant amount of the coastline inland from the water’s edge. As alluded to above, this includes major lakes, fjords, bays and naturally all of the oceans.
Tsunamis are frighteningly common in the Pacific Ocean, especially all of the Pacific Rim countries in Southeast Asia due to the preponderance of volcanoes and other tectonic activity in the region, and to a lesser extent along the United States Pacific Coast. Other frequently tsunami-affected seas include the Caribbean and the Adriatic.
Don’t get too complacent if you are landlocked, either. Places all around the globe that are far from the ocean’s edge have seen untold death and destruction from tsunamis.
Major lakes in the United States and in Europe have spawned tsunamis after they were struck by titanic landslides breaking loose off of nearby mountains.
It might be hard to fathom, but you must remind yourself that anytime and anywhere you’re local to a major body of water you could be at risk of a tsunami.
All that is required is an impact and displacement event of sufficient magnitude to shift a huge quantity of water. That will create a tsunami almost every time.
Tsunami Indicators and Warning Signs
Despite all of our scientific advances, innovations in sensor technology and general body of knowledge concerning meteorology and hydrology tsunamis simply cannot be predicted as reliably, or with any kind of certainty compared to other natural disasters.
Undersea earthquakes are the event that will reliably spawn tsunamis more than any other occurring regularly, but even so sometimes massive earthquakes will fail to spawn tsunamis at all while mild ones will. The reason is a mystery. We just don’t have enough data to say for certain.
We haven’t let that deter us, however: the United States and other countries that are commonly tsunami-affected have taken it upon themselves to install tsunami sensors and various alert systems in areas that are likely to be regularly or severely impacted by them.
These monitoring systems typically “listen” for undersea earthquakes as the primary alert mechanism. Depending on the locality, the alert can go out over public address, radio, television or by phone.
But even in the absence of these more advanced scientific systems, tsunamis you will have warning signs most of the time. Wherever you might be near the water, if you can feel an earthquake occurring you should expect a tsunami in the aftermath.
You should also keep one ear tuned to local news, as any story that reports a major meteor impact out at sea should have you worried about a tsunami also.
Beyond this, there are two common indicators of tsunamis that you can see and hear much of the time.
If you are within sight of the water where it meets the shore, and you notice the tide going out too far and too low, too quickly, you must seek shelter at once: the so-called “big dip” of the tide running far out will typically precede a tsunami’s arrival by a few minutes.
If you see this eerie phenomenon you have no time to waste! An auditory signal you might perceive is a loud, freight train-like roaring coming from the sea, also sometimes described as a sort of whooshing sound. If you hear this strange roar you will likewise only have a few minutes to get to safer ground.
Here is the checklist of possible tsunami warning signs:
- Earthquake: Earthquakes commonly instigate tsunamis, and though you might not always feel the quake that starts one, if you can feel the earth shaking while you are near the ocean you must immediately take action after the shaking stops to avoid the possible tsunami likely to follow.
- Roaring or Whooshing: If you can hear a sustained, loud roaring or whooshing sound coming from the ocean, it is almost certain that a tsunami is on the way. Do not wait, seek shelter immediately!
- Unusual or ill-timed High Tide: Every now and then, a tsunami will strike the shore unevenly, meaning one section of the shore may see an unusually high surge where the rest of the shore may not. If you notice a wave that comes way, way too high on shore, but is not otherwise terribly destructive you need to act. There’s very likely a tsunami incoming and the next wave will be a doozy.
- Sudden drop and pullback of tide: The opposite is also true. A sudden pull back of the tide that goes way lower than usual is a sure indicator of a tsunami. If you can see parts of the ocean floor that you usually can’t during low tide, you’ve got a tsunami incoming.
Seiche Waves: Similarities and Differences
Seiche waves are often described in the same breath as tsunamis since they have similar effects on people and cities on dry land, but the actual physics of a seiche wave and a tsunami are quite different.
Seiche waves occur in entirely contained or semi-contained bodies of water when they are acted against by wind and atmospheric pressure.
A strong, steady wind can in essence push some of the water far to one side of its container. This will result in a noticeable drop in the water level on one side, and a rise in the water level on the other, where the mass of water has been pushed.
When the wind stops blowing, water wants to return to its normal level and rushes back to the low side.
The resulting action works sort of like a tsunami on a smaller scale. These waves are typically less powerful than tsunamis in almost every instance, although they can be dangerous enough to have caused several deaths and considerable destruction in the past, including significant damage to buildings and even bridges.
The North American Great Lakes are particularly known for seiche waves.
Tsunami Warning! Seek Safer Ground!
If you know for certain or suspect that a tsunami is incoming you must take action at once. You could receive an official warning or notice one of the signs listed above. Either will suffice: you have to go!
Don’t take down your umbrella, don’t gather up your picnic basket; grab your loved ones and head away from the water to higher ground! There will be no time to react at all if you stick around to wait and see.
When a tsunami wave makes landfall, it could be anywhere from 10 to 100 feet high, and by the time it actually reaches the shore it is traveling at least 20 miles per hour. If you know anything about the physics of water, you know that its density provides it with tremendous power when it is moving.
Imagine a significant fraction of the ocean itself hurtling towards the shore at high speed. There is power you cannot imagine. The speed of a tsunami means you’ll have very little time to react; preemptive precaution and escape is the only defense.
Where do you go? The ideal answer is at least 1 mile away from shore and to the highest possible point above sea level. Authorities recommend a minimum safe height of 100 feet.
After the initial surge passes, stay where you are! There will statistically be several more waves on the way, and they could be right behind the first one. Also remember what I said above; the first wave is rarely the strongest.
What should you do about a tsunami if you are in a boat or other watercraft? The answer depends on how close you are to shore.
You might be surprised, but tsunamis are rarely dangerous out in the middle of the ocean. All that momentum and mass only gathers destructively when they near the shore.
In the middle of a body of water, they often race past harmlessly with people on board vessels none the wiser. It is an entirely different story when they do reach the shore though, as that is where they rise rapidly and crash sweeping everything with them.
If you are in a boat and very near shore, I mean right near shore or the dock, your best bet is to tie off and head in land to someplace high as described above.
If you’re not near shore and get a tsunami warning, your best bet is to head for open water as fast as you can, directly steering in to any waves that may be coming your way. If you’re far from shore when the tsunami hits, you will be safe from both the impact and the subsequent recession.
Surviving Before, During and After a Tsunami
Any comprehensive disaster survival plan must incorporate procedures to follow not only during a disaster, but also before and after.
The following tsunami guidelines have been provided by FEMA and the United States DHS. Countless hundreds of millions of dollars in research have furnished these guidelines and they were crafted by the best and brightest disaster readiness and tsunami scientists in the world, so I suggest you listen up!
Before a Tsunami Occurs
All of the steps in this phase are to take place before a tsunami occurs, meaning when you aren’t worried about a tsunami bearing down on you.
This is the preparation phase. If you’re going to be living, visiting or working in an area that is tsunami vulnerable or tsunami-prone, you’ll have a little bit of homework to do.
- In any tsunami-prone or tsunami vulnerable area, make it a point to investigate official emergency response plans, evacuation routes, and safe areas. Learn which footpaths and roadways are marked and designated for tsunami evacuation. Make sure you learn a few alternates, also, as any roadway can become clogged by a teeming throng of evacuees during an emergency.
- Take the time to learn the typical tsunami warning signs for the area you’ll be in. Areas that have been struck by multiple tsunamis in the past will often report the same symptoms, possibly the roaring sound, or possibly the tide pulling way back.
- Fast reactions are essential for surviving a tsunami once a warning has been issued. It is well worth your time to do a couple of dry run scenarios along evacuation routes.
- Make sure you research and select safe havens and rally points based on their height above sea level. Higher is always better.
- Plan, discuss and practice an emergency comms plan with your family or people in your group. Also set up at least one mutual emergency contact who is well away from any potentially tsunami affected area.
- Sign up for any and all tsunami warning services on the local and national level. If a tsunami warning or watch is received, heed it and act.
When a Tsunami Warning is Issued or a Tsunami is Incoming
Now is the time to take preventative action.
- If you are experiencing an earthquake prior to the tsunami, drop, seek sturdy cover, protect your head and neck, and wait until the earthquake ends before you enact the rest of your plan.
- Note that if you are not within a tsunami affected zone when a tsunami warning is issued, stay where you are and wait for guidance and instructions from officials.
- If you are within the tsunami affected zone you must get to the highest available ground that is as far from the water as possible and do so as quickly as humanly possible. Do not wait for official guidance or instructions if you know a tsunami is incoming! Any delay may be fatal.
- If you cannot get far in land, take cover atop the tallest and strongest building that is nearby. If no buildings are around, find a mature, healthy tree and climb as high as you can.
- Once a tsunami wave reaches shore, you must stay out of the water at any cost. It can sweep you away, or pull you under instantly, and it will be a churning mass of wreckage and debris that can crush and mangle you.
- If you are able, keep one eye or ear on the emergency notification system for tsunami developments.
- If you are in a boat or other watercraft that is near the shore when a tsunami warning is issued tie off or anchor your boat and enact your onshore tsunami survival plan.
- If you’re in a boat or other watercraft that is not near shore when a tsunami warning is issued, you need to head out to sea as far as possible while steering directly into any waves that are approaching.
- Most importantly of all: if a tsunami warning is issued you must evacuate at once with no delay!
Surviving the Aftermath of a Tsunami
- Tune in to emergency alert systems to get updates on the status of rescue and relief efforts.
- Stay out of the flood waters left behind by a tsunami’s passage if at all possible. Floodwaters will contain physical as well as pathogenic hazards. If you are unfortunate enough to be in the existing flood waters when a secondary wave arrives, you are very likely to be drowned, swept out to sea, or crushed.
- Downed or underground power lines are likely to energize floodwaters to lethal effect. You must remain constantly alert for any potentially energized equipment.
- Be especially cautious of any building or bridge that could have been damaged by the tsunami or any earthquake that preceded it.
- Avoid using phone systems unless it is to send an email or a text. If the networks are still functional, they will be badly clogged by traffic. You won’t help matters by trying to send an emergency call even if it is a real emergency. Find an alternate way to communicate.
Pack and Keep Handy a Tsunami Survival Kit
The odds are very good that any tsunami event will displace you from your home for a significant length of time.
If you were caught out unawares and unprepared, survival may be miserable or even uncertain. A small or modestly sized backpack or messenger bag full of survival supplies is unobtrusive enough to go with you everywhere in tsunami country.
Remember, you must keep this bag with you or very close at hand: you won’t have much time to react as it is when a tsunami warning is issued or when you notice a warning sign that one may be closing it. You won’t have time to dash home and grab it.
Your tsunami survival kit should contain the following items below as a basic core.
- Food: Basic survival foods will be shelf-stable and calorie-laden food items that you can munch on while you wait for rescue or for the waters to recede. You can consider prepper staples like trail mix, beef jerky and energy bars, or go big and really pack in the calories with an MRE. Even if you’re only in for a wait of a couple of days, you’ll be glad to have the food to quell your rumbling tummy.
- Water and Water Filter: The destruction and flooding caused by a tsunami utterly ruin public water supply systems, and also stand an excellent chance of overflowing sewage systems to nasty effect. A quality water bottle combined with a high performance portable filter and water sterilization tabs will give you several options for making questionable water safe to drink, and will definitely spell the difference between that and dehydration.
- First Aid Kit: A small first aid kit should be able to take care of minor injuries and some pretty major wounds. You and other people are likely to sustain both during a tsunami if you are unlucky or just slow to react. Note that this item won’t do any good if you don’t have the skills to use its contents effectively. Make sure you get training and then practice with your medical gear so you can use it when the time comes.
- Multitool: A multi-tool is invaluable no matter what kind of disaster you are facing. You use this for all kinds of general repair and survival tasks in the wake of a tsunami.
- Flashlight: Even the smallest tsunami has an excellent chance of knocking out power in a wide area entirely. That means you’ll need a flashlight, and potentially a headlamp also, in order to see in the dark. For work details, signaling and navigation you should choose a flashlight or headlamp with a good combination of brightness, run time and optional modes.
- Pry Bar or Hatchet: There’s a very good chance you’ll need to dig your own way out of a building wrecked by a tsunami or help someone else dig out. A pry bar or a small hatchet will definitely help you do that, and can also pull double-duty as a good defensive tool.
- Gloves: The swirling flood waters left behind by a tsunami, to say nothing of the field of wreckage after the water recedes, will be sharp and jagged by its very nature, and that means you’ll need something to protect your hands. I recommend a heavy-duty pair of leather work gloves for durability and puncture resistance.
- Spare Battery or Power Bank: If you have a smartphone, satellite phone or other electronic device that can help you in a pinch, make sure you have a spare battery for it that stays charged or a power bank to recharge the battery in the device. Remember, you are not going to have any local power after a tsunami.
- Tarp: A durable, lightweight, high quality tarp will serve as both ground cover, and temporary shelter from rain and sun after a tsunami. You can also rig it up as a high-capacity rain catcher to hold fresh drinking water. Make sure you include a hank of durable cordage such as paracord to help you hang it, and arrange appropriately.
- Lighter and Tinder: You always need a good reliable way to create fire. It isn’t fancy and it isn’t traditional, but a quality lighter will do the job faster and easier than almost anything in all circumstances. Make sure you bring along some high-quality waterproof tinder tell to get a fire going, since dry tinder and fuel may be in short supply after a tsunami.
- Space Blanket: These foil blankets will have you feeling and looking like a baked potato, but just like a baked potato you’ll be quite warm. These weigh almost nothing and pack down to a tiny size but are invaluable for staving off exposure or reflecting the heat from a fire to help you or your clothing dry out. Don’t leave this out of your kit!
- Underwear and Socks: Moving and working in the aftermath of a tsunami means you are going to get wet and soggy. Between your own lack of cleanliness and the filthy water infections in your nether regions and any places that are kept dark and closed off, (say, within your shoes or boots) will be vulnerable to gribblies. Being able to change into a fresh, dry pair of underwear and socks will go a long way towards keeping you happy and infection free.
- Pad and Pen: Don’t waste your time or your phone’s power by trying to take important notes on its notepad function. Instead, rely on an old-fashioned analog notepad and a simple pen or pencil. You might use this to write down important details on the situation at large, pass along messages or all kinds of other important info. A good and cheap upgrade is a waterproof pad of paper and all-weather pen or pencil.
- Map and Compass: You can go ahead and bet that you won’t even be able to recognize the area you’re in after a tsunami strikes it. They really are that destructive. Your only hope in navigating efficiently without getting lost will likely come from a map and a compass.
- Cash: Even if the electricity is still on, and it won’t be, trust me, the network infrastructure necessary to run credit card and debit cards is probably going to be four-legs-to-the-sky after a tsunami. You’ll still be able to get what you need from businesses or people alike if you have a wad of cold, hard cash. Keep it close and keep it safe.
Any tsunami is an immensely powerful, sudden and devastating disaster. In fact, they’re one of the most ferociously powerful disasters that can strike with very little or no warning.
This makes preparation, planning and fast action all the more important if you are living or working in a tsunami-prone area.
You must stay on alert, stay on guard, be ready to drop everything, and literally run for the hills if you hear a tsunami warning or suspect one is approaching. Use the information and the guidelines presented to craft your own tsunami survival plan.
P.S. Check out this govt website for a map of tsunami warnings across the Globe.
Tom Marlowe grew up with a gun in his hand, and has held all kinds of jobs in the gun industry: range safety, sales, instruction and consulting, He has the experience in helping civilian shooters figure out what firearms work best for them.