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How to survive a tsunami

If you, your family, or friends ever go near the shore of the ocean or a lake, you need to learn about tsunamis. Unfortunately, the current public perception of the tsunami hazards is all too often a three-step denial: (1) It won’t happen to me. (2) If it does, it won’t be that bad. (3) If it is bad, there’s nothing I could’ve done anyway. This perception must be changed in order to save lives and build a culture of tsunami hazard preparedness.

So, the logical question is “When will the next big tsunami strike?” Probably after the next really big earthquake under or near the sea. As the father of modern seismology, Charles Richter is reported to have said, “Only fools and charlatans predict earthquakes.” But the odds of a large earthquake do increase every year without one. As weird as it may seem, small earthquakes are a good thing. They literally relieve the stress along seismically active areas. Long periods of time without quakes in these areas means that the pressure is continuing to build and may well be relieved by a really big quake. Those areas that are normally seismically active but have had no stress-relieving earthquakes are known as “seismic gaps.” And there are numerous seismic gaps around the world. For example, the Cascadia Subduction Zone, lying just 50 miles offshore of Oregon, Washington state, and southern British Columbia. It is similar to the fault zone off the coast of Sumatra that caused the 2004 Indian Ocean tsunami. Then there’s the area around the popular tourist destination of Acapulco, Mexico, which sits in a seismic gap that hasn’t had a significant earthquake in over a century, and has been described as “a tectonic time bomb waiting to go off.” And then there’s Alaska with 3 gaps which have had no large earthquakes in the past century. Chile has one too, off its northern coast—and the list continues.

So, the clock is ticking.

But tsunamis are generated not only by earthquakes, but also by landslides, volcanic eruptions, and other, much weirder, causes. Most of the fatalities caused by the 1964 Good Friday earthquake in Alaska—82 out of 131 total deaths—were caused by local tsunamis generated by underwater landslides set off by the earthquake. Landslides, from the land into the sea or underwater can also be set off by other causes including heavy rain, rising sea level, and even gas bubbles trapped under the sediment lying on the seafloor that suddenly decide to pop!

So, what can we do? Not only do the chances of another tsunami increase every year, but with every year that passes, more people forget the danger. For example, Hawaii is experiencing the longest period in recorded history without being struck by a Pacific-wide tsunami, with over 60 years since the devastating 1960 tsunami from Chile. And with every year that passes, coastal populations continue to grow, and there are fewer and fewer people alive now that experienced a tsunami, take the threat seriously, and know how to respond. People often assume that in the event of an emergency they will be evacuated by first responders, i.e. police and fire department personnel. The problem with that assumption is that there simply aren’t enough first responders to carry this out, and based on our experience, in many cases they have not had adequate training due to lack of funding or time dedicated to working on natural hazard protocols. What about education of the general public or children in schools? Similar problem. This author once had a state Governor tell him, “We can’t educate the public about tsunamis. It would scare away the tourists.” Add to this the threat from local tsunamis, where for many areas there is simply no time for tsunami alerts and therefore there could be no action by emergency management and first responders. The need for tsunami preparedness education is critical. Every hotel is required to have fire evacuation information posted on the back of the door of every hotel room. But for hotels near the coast there is little or no tsunami information for hotel guests, even in beach-front hotels. And it goes well beyond hotels.

People run from the approaching tsunami in Hilo, Hawai’i on 1 April 1946. note the wave just left of the man’s head in right centre of image.

Many coastlines do not have tsunami warning signs, fewer have marked evacuation routes, and even if they did, what do they mean? Without education the signs have little value, and tsunami education is patchy at best. In our time-challenged lives, education messages need to hit home and often. Start at Grade 1 and build from there every year, involve parents, grandparents, and friends, and soon tsunami education and awareness become a normal part of the fabric of life, like using an umbrella when it rains. Every coastline is different, every tsunami is different, which is why everyone needs their own plan to keep it simple and to stick to it. Where is the nearest high ground or four-storey concrete reinforced building? How long does it take to walk there? Where is the family meeting point? Does every family member know their plan? The KISS principle is best: Keep It Simple Stupid. For example, a car might seem a logical option and will definitely be one of the only options for the unprepared, but if everyone panics there will be traffic jams, crashes, gridlock, and precious minutes lost—and if the tsunami catches you in a car…

While there may not be tsunami warning signs and evacuations routes marked, there are tsunami warning systems in many parts of the world and as such there is often time for evacuation in areas that are distant from the source of the tsunami. But for locally-generated tsunamis, especially those created by landslides, there may not be time for an official warning. You need to know what actions to take without hesitation—hence you need to have a plan. Learn where the tsunami hazard zones are around where you live, work, and play. Figure out the fastest and safest evacuation route. If you have children in school, check to see if the school is in a tsunami hazard zone, and if so, make sure they have an evacuation plan and practice it. Education goes both ways: parents can educate the school too. In the event of a Tsunami Warning, do not go to the school to grab your children. By the time you get there, they will already have been evacuated and rushing to the school will only add chaos to the situation and put you at risk.

This is all well and good, these are the perfect education and evacuation scenarios, but what about where there are no signs, no marked hazard zones, no warning system? Worse still perhaps, everybody is a tourist at some point in their life. What if the coast is unfamiliar, perhaps the language too, and so on? What do you do? Finding high ground or a safer place (e.g. a tall building) is easy: you look. Be aware of the warning signs: did you feel an earthquake, is the sea rapidly receding from the coast, or did a wave suddenly come in much further than usual? All these are potential precursors of what is to come. Move away from the coast and inland, these minutes and seconds could save your life. If it is a false alarm though, do not feel stupid, feel empowered: you knew what to do and you followed through.

What does the future hold? Have we learned from our mistakes? Will we forget the danger posed by tsunamis as time passes or will we educate and prepare for the next inevitable tsunami to save lives? It’s not if another tsunami will strike, but when!

Featured and secondary images from Wikimedia Commons.

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