The height of a tsunami in the deep sea, from trough to crest, can only reach a height of around 3 feet (1 metre), as we have shown in the preceding pages, because the majority of a tsunami rests below the sea's surface. As a result, tsunamis can arrive suddenly and are difficult to detect when they move across the open ocean.
To detect tsunami movement within the water, a global network of deep sea sensors would be required, but that is difficult to construct.
Building the monitoring and communications infrastructure required to send out timely warnings is a massive effort that presents significant challenges, especially for the world's poorest regions.
The precise timing, location, and size of a tsunami's landfall are all difficult to predict, even with the most advanced technology and a wealth of seismic data. After a magnitude 7.0 or greater earthquake is detected near or beneath the ocean, all that tsunami warning centres can do is immediately send out an alert to all coastal communities that are concerned.
Local authorities must identify what steps must be done following a tsunami warning and provide clear instructions on evacuation methods. There is hardly much time for evacuation after a tsunami warning.
Although accurate, today's warning systems are sadly unable to provide timely information in the event of an earthquake close to the coast.
Fortunately, there are a few simple natural warning signs that can help you understand when a tsunami is about to strike. They consist of:
A strong earthquake may have created a tsunami if you are near the store, thus you should quickly flee to higher ground or inland, avoiding river valleys:
Unusual sea level changes are a warning indicator that a tsunami may be on its way.
Coastal waters should noticeably rise or fall quickly. If you notice a beach's water suddenly receding, exposing the ocean bottom (the so-called disadvantage), or a sudden rise in sea level, get away right away to higher ground or inland, staying away from river valleys;
The initial wave in a tsunami wave train is typically not the biggest, so if you witness a wave that appears to be abnormally large, much stronger waves may be on the way. Avoid river valleys and head as quickly as possible to higher ground or inland;
If you hear an offshore roaring noise that sounds like a train or jet plane, a tsunami may be on its way. Run for higher ground or inland, staying away from river valleys.
If you encounter any of the aforementioned events, leave right away without waiting for formal evacuation orders. Avoid river valleys and immediately evacuate low-lying areas because additional waves are likely to arrive after the initial one and each wave can last up to 30 minutes. The threat might linger for many hours or even up to 24 hours.
Artificial Tsunami to alert the public to the potential risk, warning signs and sirens have been installed alongside the roadways of numerous beaches across the world. These signals should not be ignored, and prompt action should be done if any of the natural signs mentioned above occurs. A prompt response could save countless lives.
