When the earth moves during an earthquake, its force is not limited to the ground itself. Sometimes, these vibrations reach the depths of the ocean, and within minutes, the seemingly calm ocean begins to move toward the shores as a tsunami. Now the question is how does the water become a tsunami on such a large scale immediately after the earthquake.
Movement of tectonic plates:
The main reason for this is the movement of tectonic plates. Beneath the earth are many large plates, which are constantly moving at a slow speed. When two plates suddenly collide or one plate slides under the other, energy is released, causing an earthquake. If such movement occurs under the sea, the shocks travel directly to the sea floor.
When a large portion of the ocean floor suddenly rises or sinks, large volumes of water beneath it also move rapidly. This sudden displacement of water begins to move in the form of large waves. These waves are common in the deep ocean, but as they approach the coast, their height increases due to the decreasing depth of the water. These high waves are called tsunamis.
This relationship between tsunamis and earthquakes has been the subject of scientific study for decades. The 2004 Indian Ocean Tsunami is a prime example of this. A 9.1-magnitude earthquake near Indonesia wreaked havoc in 14 countries in just a few hours. Millions of people lost their lives, and thousands of kilometers of coastline were affected.
In addition to earthquakes, tsunamis can also occur from underwater landslides and underwater volcanic eruptions. Landslides at sea level disrupt the water balance, while volcanic eruptions release sudden energy, causing huge tidal waves. Although ocean earthquakes remain the most common cause of tsunamis, scientists still cannot accurately predict tsunamis, but many countries are now working on early warning systems. In India, INCOIS is playing a key role in issuing such alerts.