Knowing More About Tsunamis

In this article, we are going to discuss tsunamis, what causes them, and their typology. Tsunamis are humongous waves triggered by volcanic eruptions or earthquakes under the sea. They do not increase in height further into the ocean. However, when the waves go inland, they build up to greater and greater heights as the ocean’s depth drops. The speed of a tsunami wave is measured with the help of ocean depth and not the distance from the source of the particular wave. Tsunami waves move rapidly in deep water, only slowing down when they approach the shallow reaches. 

What Causes Tsunamis?

Large underwater earthquakes that start from the right tectonic plate and border are often known to be responsible for these heavy waves. It occurs when the bottom of the ocean abruptly increases or decreases at the boundary of the earth plate. And when this happens, the water displaces itself above the changes and launches a roll of waves that creates a tsunami. 

Almost every tsunami, approximately 80% of them, started at the Pacific Ocean’s ‘Ring of Fire’. This place is a geologically activated area where you can experience the movements of tectonics, which cause volcanoes to erupt, followed by earthquakes. 

The volcanic explosions have the potential to launch a tsunami. It can also be launched if a huge meteorite hits the Earth, as evidenced by its ancient history. 

Tsunamis are ocean waves that are caused by:

• Huge earthquakes that take place near or beneath the ocean
• Eruptions of volcanoes
• Landslides beneath the sea
• Onshore landslides cause significant amounts of material to get dropped into the ocean
• The name ‘tidal wave’ is not used by scientists since such waves are not created by tides
• Waves of tsunami differ from the conventional ocean waves caused by storms and winds, as they do not break, such as the curling and wind-generated waves that are famous among surfers

Tsunamis are often composed of several waves which happen to rush onshore like a rapidly increasing tide with strong currents. Tsunamis behave like an extremely rapid flowing tide that reaches further inland compared to the normal water as it approaches the beach. 

Tsunamis can come in different sizes, such as micro-tsunamis, which can be detected by sensitive sensors on the given ocean floor. In contrast, mega-tsunamis have the potential to devastate the entire ocean and land, such as the 2004 Indian Ocean tsunami. If you ever listen to a tsunami warning, you will witness visible shaking near the water and coast; in such cases, go to higher ground and stay away from the coast until the wave activity has abated (usually several hours to days).

Difference between Tsunami and Tidal Wave

Despite the fact that both are tsunamis, sea and tidal waves are distinct and independent occurrences. Tidal waves are considered to be waves that are created due to the Sun, Moon, and Earth’s gravitational interactions. But tsunamis occur due to major earthquakes under the ocean, such as submarine landslides, onshore landslides, volcanic eruptions, or if you dump a humongous amount of material in water. 

Tsunamis may travel at up to 805 Km per hour, which is roughly the speed of a jet airliner.  At that speed, they may span the whole Pacific Ocean in less than a day. And, because of their long wavelengths, they lose very little energy along the way.

Tsunami Early Warning Systems

Tsunami threats have compelled several Pacific basin governments to create tsunami warning systems. A warning may begin with a notice from a geological organisation that an earthquake of sufficient magnitude to affect the ocean’s surface (for example, magnitude 7.0 or greater) has occurred. Meteorological agencies may then record anomalous changes in sea level, which the warning centre may combine with data on the depth and characteristics of the ocean floor to predict the tsunami’s course, magnitude, and arrival time.

Depending on how far away the seismic disturbance is, government officials may have several hours to order the evacuation of coastal regions. A tsunami warning centre in the Pacific Ocean is located in Honolulu, Hawaii. It was founded in 1949 after three years of tsunamis caused by a subsurface earthquake near the Aleutian Islands slammed the island of Hawaii, killing over 170 people.

Conclusion

Early notice, which permits people to reach higher ground, is the best defence against any tsunami. The Pacific Tsunami Warning System, a consortium of 26 nations based in Hawaii, operates a network of seismic equipment and water level sensors to detect tsunamis at sea. Similar methods are being developed across the world to safeguard coastal regions.