There were no tsunami waves caused by this earthquake at all, despite some panic that there may be. The warning was taken off after about half an hour, but many people didn’t know it had been, so the panic continued. There is very little (but still some) risk of a tsunami from this fault. Other active faults are further from Belize.
The word ‘tsunami’ is Japanese. The English word for them used to be “tidal waves” but this is inaccurate as they have nothing to do with tides. There are very few languages with their own word for them because they are rare in most of the world. They are caused by undersea volcanoes, earthquakes and landslides and are still quite poorly understood by scientists. This is partly because they don’t happen often and also because there is no warning that they are about to happen, except for an earthquake which also can’t be predicted with any accuracy. Around 80% of them occur in the Pacific Ocean, triggered by the earthquakes and volcanoes around the ‘Pacific Ring of Fire’ – see last post. Japan is the most advanced country in their research as tsunamis hit their coastline every year.
Due to the devastating tsunami in Asia on 26th December 2004, the word ‘tsunami’ now strikes terror in the minds of most of us. Before this time, most people had little knowledge of what a tsunami was. However the conditions of a tsunami’s formation need to be very specific for it to form such terrifying waves.
2004 Asian earthquake and tsunami
The fault that caused the 2004 earthquake leading to that terrible tsunami was a massively long subduction fault meaning that one side slipped down in relation to the other over a distance of almost 1000 miles. The earthquake was the fourth largest ever recorded and the longest ever in duration (upto 10 minutes) and occured at a depth of 19 miles. This subduction fault is far out in the deep ocean running north-south, and the earthquake vertically displaced a huge column of water and set it into motion – the greatest power of which ran perpendicular to the fault, so in an east-west direction. These waves are just a blip in the deep ocean, and you would probably not even notice it if you were in a boat as it passed underneath you. The waves travelled hundreds of miles through the deep ocean before getting to the shallower seas, which is where it becomes dangerous. As the base of the waves drag on the sea bottom, it compresses the water, slowing down the waves, and it causing the waves to gain in height. We all know the devastating consequences. Depending which cycle (the crest or the trough) of the wave hits land first, witnesses may see the ocean being sucked out, which sadly added to the death toll in this case as many people wanted to see this phenomena, and to collect stranded fish. Very few people had the knowledge to realise this meant an approaching tsunami. In other areas, the wave hit without warning. This type and scale of tsunami is hopefully a once in a lifetime, or even several lifetimes occurrence. It is also thought that the destruction of coastal mangroves, coral reefs and sand bars in many of the affected areas contributed to the suffering as there was no longer any natural protection. The areas were heavily populated and with no warning system, the death toll is thought to be around 300,000, although the final figure will never be known as some of the areas affected were very remote. Hopefully now that the world is better educated, and there are some warnings in place, such a large death toll won’t happen again.
Our earthquake
Check the previous post for more science behind the earthquake itself
The fault that caused the Honduras earthquake on Thursday morning is a transform fault which instead grinds side to side, causing less displacement of the water. Because it is much closer to land and in shallower water, there was also less potential for a huge body of water to gain momentum. That isn’t to say that a tsunami won’t ever occur from this fault boundary. It may do, but is extremely unlikely to be anywhere near the scale of 2004. There just simply isn’t the volume of water needed to produce that or the vertical displacement as from a subduction fault. This fault runs approximately east-west, so the greatest displaced volume of water would run north-south.
So why the warning?
The Pacific Tsunami Warning Center took a lot of criticism after the tsunami in 2004, as they didn’t send out warnings to the countries affected. There was a break down in communications. It seems to be standard practice for them to now issue these warnings to coastal areas whenever an earthquake happens under the sea. Of course they are doing the right thing, as it’s better to be safe than sorry. They need to make a split decision as timing is very short. In the case of this earthquake, had a tsunami happened, it could still have had a terrible effect on the low lying coastal areas even with a small wave height, and would have hit in a very short time, probably in about half an hour. In fact Belize, along with all coastal areas, gets regular tsunami warnings, and they have all come to nothing, but none of us would know that. The reason word went around so quickly and the authorities were worried is because we all felt and were awake from the tremors. Unfortunately few of us realised that the warning was lifted after a very short time.
Our natural protection
The proximity of the coral reef will always protect us to a certain extent – the reef to the rescue yet again! We love you barrier reef! Tropical storms and hurricanes can and do produce huge ocean swells and waves, and the reef takes the majority of the impact from them, which is precisely why these Cayes still insist. More about that on the website and on the previous post “Protect coral reefs to provide for one billion people”. Without the protection of our reef, the Cayes would be washed away in no time. Mangroves, wetlands, and forests also provide a huge amount of natural protection against ocean swells caused by storms, hurricanes or tsunamis.
Is Belize at risk from other tsunamis?
This is difficult for any scientist to predict. To quote a forgotten writer, ‘ask four scientists and get twelve different answers’. It is possible, but unlikely. As stated above, we are unlikely to get a tsunami from this fault as it is a transform fault. Most tsunamis are caused by subduction faults, and we are not that close to any of those. There are several on the Pacific side of Central America, so that coast is at risk. Elsewhere in the Caribbean there is also risk from the Hispaniola Trench and the Puerto Rico Trench, which at 27,362 feet below sea level is the deepest point in the Atlantic Ocean. These are both some distance from us in Belize, and also run in an approximately east west direction, meaning that the greatest risk is south and north from there rather than west. There are also several islands between these areas and ourselves, so although a tsunami generated here may reach us, much of its power and height would have dissipated, and we would get some warning.
Some scientists believe that the whole of the Atlantic and Caribbean coasts are at risk from a mega-tsunami which could be triggered by a landslide when a large volcano on La Palma in the Canary islands (close to Africa) erupts. They believe that it could happen at any time, but it could also take many more hundreds or thousands of years. When geologists talk about something happening soon, you need to remember that they are used to thinking in millions of years, so they don’t necessarily mean in our lifetimes. Other scientists dispute whether the tsunami would indeed cross the entire Atlantic. Certainly it would be affected by the powerful currents of this massive ocean. Again no one really knows the answer. If it did happen, it would take many hours to reach us (though very much faster than a hurricane, more like the speed of a transatlantic airplane), and we would hopefully receive sufficient warning to evacuate, or at least prepare.
So overall this scientist believes that while there is a possible risk from a tsunami in Belize, it is very unlikely. Should one occur we would be greatly vulnerable as many of our communities are on low lying islands and coastal plains. They are something we should educate ourselves about, but there really is no need to panic. When we hear about the threat of a tsunami in the Caribbean, or Central America, we need to remember that they are talking about the whole region and that we need to look at specific areas to asses our real threat.
There is a planned tsunami warning system for the Caribbean, which should go online next year. UNESCO says that eventually there will be a global system, meaning that everywhere should receive appropriate warnings.
What should you do if a tsunami is expected?
If one is coming immediately, get up as high as you can, if you are in or near a high rise hotel or complex, run up to the top. If you are not near one, either climb a tall tree and lash yourself to it with whatever you can find, or run as far from the sea as you can get. If there is time, run far from the sea and then climb a tree. Very sadly alot of the fatalities in 2004 were very young children as the force of the water wrenched them from their parents’ arms. As parents ourselves, this would be one of our greatest fears too. Anything you can do to lash your child to yourself, even tying them inside your tee-shirt should help, or looping your belts together. However it’s the same as they tell you on the airlines, you must make sure you are safe in order to care for your child. Of course if you are climbing trees, you can push them up higher than you can go. One fireman caught near the beach in the Asian tsunami saved his entire family by doing just that. He threw them into a tall tree, climbed up himself and they tied themselves to the tree with their clothing and towels, which helped them hold onto the tree as the strength of the waves tried to rip them off. If you have time to grab a bottle of water, all the better as it may be some time before you can get fresh water again.
For more on tsunamis and their formation
Tags: Belize, earthquake, education, global, threat, tsunami