Written by Sofiya Shahiwala
We all know about the logical reason behind the occurrence of waves, typically known as Tide and Ebb. A Tide or Ebb acquires its energy via the gravitational forces. A Tsunami is one such phenomenon which involves waves but obtains the energy from a force which is much distinguished.
Today, on the World Tsunami Awareness Day (celebrated every year on the fifth of November), let us talk about what Tsunamis are and how they occur.
A Tsunami is typically a series of enormous waves that take place because of underwater activity. This activity could be a Volcanic Eruption, submarine landslides, the movement of Tectonic Plates or the most common, Earthquake.
When a Tsunami is far from the shore, it is barely detectable. However, as it gets nearer to the shore, because of Wave Shoaling, the height of the wave increases. A Tsunami wave could travel at over 800 km per hour in the deep ocean. As it approaches the shore, the velocity decreases to almost 80 km per hour. The opposite happens with height. As the wave approaches the shore, its height increases to almost 10 meters.
These waves look like walls of water, occurring for hours, coming in every 5 to 60 minutes.
It is intriguing to note that Tsunamis occur most often in the Pacific Ocean. This is because of the many large earthquakes associated with the margin of the Pacific Ocean Basin, also called the “Ring of Fire”.
Tsunamis can cause extensive loss to life as well as property. The large waves not only drown everything near the coast but can also travel a mile inland or more. The water brought by the waves then recedes back to the reservoir, taking along with it, debris, houses, broken trees and lives.
The Tsunami which occurred in the Indian Ocean in 2004 is marked as one of the deadliest Tsunamis in History. It killed over 225,000 people in South Asia and directlyaffected about eight countries.
The Government has done much to prevent damage from upcoming tsunamis. Flood Walls, Flood Gates, and Channels (to divert the water) have been set up in some areas to stop or reduce the water flow coming in the towns. However, in 2011, a Tsunami had overtopped the wall created to protect Japan’s Fukushima Power Plant. This resulted in three large explosions and nuclear leakages. It was recorded as the largest Tsunami in Japan, resulting in above 15,000 deaths.
Scientists currently focus upon detecting early signals of Tsunamis and underwater earthquakes, thereby alerting the towns and cities near the coastal regions.
This year, with the fourth edition of World Tsunami Awareness Day, the target of UNISDR through the ‘Sendai Seven Campaign’ is one which focuses on reducing disaster damage to critical infrastructures and the disruption of basic services.