TSUNAMI

TSUNAMI

Tsunami means “harbor wave”. A tsunami, also called seismic sea waves, is one of the most powerful and destructive natural forces. It is a series of extremely long waves caused by a large and sudden displacement of the ocean due to earthquakes, volcanic eruptions, etc. When they reach the coast, they can cause dangerous coastal flooding and powerful currents that can last for several hours or days.

Causes of Tsunami

• Earthquake: Tsunami is generated by the earthquake because of the disturbance of the seafloor and is formed generally with vertical displacement. Most Tsunamis are generated by earthquakes that occur along the subduction boundaries of plates along the ocean trenches. The size of the Tsunami is related to the size of the earthquake.
  • For Example: 2004 Indian Ocean Tsunami was an earthquake-induced Tsunami, caused by an earthquake (Mw 9.2) in the Indian Ocean.
• Underwater explosion: It is an example of man-made disaster. Massive explosions created by a nuclear weapon or nuclear tests have the potential to cause a Tsunami. There have been dangers of using this as a tectonic weapon.
  • For Example: A Nuclear Testing by the US generated Tsunamis in 1940 and 1950s in Marshall Island.
• Volcanic eruption: Volcanoes that occur along the coastal waters can cause several effects that can cause a tsunami.
  • For Example: 1883 Indonesia Tsunami was caused by the explosion of Krakatoa volcano.

Characteristics of Tsunami

• Most Destructive: Tsunamis are among Earth’s most infrequent hazards, and most of them are small and non-destructive.
• Series of waves: Tsunamis generally consist of a series of waves, with periods ranging from minutes to hours.
• Radiate: Tsunamis radiate in all directions from the point of origin, and they can cover entire ocean basins.
• No prediction: There is no season for tsunamis. We cannot predict where, when, or how destructive the next tsunami will be.
• Not all tsunamis act the same: An individual tsunami may impact coasts differently. A small tsunami in one place may be very large a few miles away.
• Tremors main cause: Tsunamis are waves generated by the tremors and not by an earthquake itself.
• The effect of Tsunami would occur only if the epicenter of the tremor is below oceanic waters and the magnitude is sufficiently high.
• Threat to coastal communities: A tsunami can strike any ocean coast at any time. They pose a major threat to coastal communities.
• Speed depends on depth of water: The speed of the wave in the ocean depends upon the depth of water. It is more in the shallow water than in the deep ocean. As a result of this, the impact of a tsunami is more near the coast and less over the ocean.
• Wave height: They have a small amplitude (wave height) offshore. This can range from a few centimeters to over 30 m height. However, most tsunamis have less than 3 m wave height.

Effects of Tsunami

1. Social

• Loss of lives: After the tsunamis reach the coast, an enormous amount of energy stored in them is released, which causes colossal loss of lives as well as the infrastructure of the place. As the port cities are economic hubs and densely populated, the damage caused by the tsunami is devastating.
  • For Example: The Tsunami of 2004 in the Indian Ocean is one of the devastating natural disasters in modern times. It took a toll of nearly 230,000 people living on the coasts of the Indian Ocean.
• Spread of disease: Flooding and contamination of drinking water can cause diseases such as Malaria to spread in the tsunami-hit areas.
• Psychological effects: Victims of such events often suffer psychological problems such as PTSD (Post Traumatic Stress Disorder), which can last for days, years, or a lifetime.

2. Economic

• Affect coastal life: Tsunamis are extremely dangerous to coastal life and coastal property. They produce unusually strong currents, rapidly flooding the land and causing great damage to coastal property and life.
• Affect infrastructure: The flow and force of water and the debris it carries can destroy boats, vehicles, and buildings and other structures as the tsunami moves across the land.
• Economic losses: Massive economic costs hit communities and nations when a tsunami happens, severely affecting the economy of the nation.
• Poor nations are more prone: Poor nations are more prone to large-scale destruction as the infrastructure is not well developed, and warning systems are not robust or unavailable. Also, their ability to cope with such a massive disaster remains inadequate.

3. Environmental

• Destroy biodiversity: Tsunamis not only destroy human life, but also have a devastating effect on animal and plant life and other natural resources. A tsunami changes the landscape. It uproots trees and plants and destroys animal habitats.
• Contamination: Contamination of soil and water is the second key environmental impact of a tsunami.
• Nuclear threat: There may be nuclear pollution due to radiation resulting from damaged nuclear plants, as it happened in Fukushima, Japan, in March 2011.

4. Governing

• Difficulty in rescue: Unfortunately, escaping a tsunami is nearly impossible. Hundreds and thousands of people are killed by tsunamis, most commonly by drowning, electrocution, explosions from gas, and collapsing of buildings, etc.