What are Tsunamis? How and where are they formed? What are their consequences? Explain with examples. (10 Marks, 150 Words)

Q.7 What are Tsunamis? How and where are they formed? What are their consequences? Explain with examples. (10 Marks, 150 Words)

Approach

Begin by defining tsunamis and explaining how they differ from normal ocean waves.

In the body, discuss the major causes of tsunamis (earthquakes, volcanic eruptions, landslides, and identify regions most prone to them (Pacific Ring of Fire, Indian Ocean). Then, examine their consequences (loss of life, displacement, environmental damage, economic losses, and strategic risks) with relevant examples like the 2004 Indian Ocean Tsunami and 2011 Japan Tsunami.

Conclude by stressing the importance of early warning systems, resilient infrastructure, and international cooperation for mitigation.

A tsunami is a series of extremely long waves caused by a large and sudden displacement of the ocean, usually the result of an earthquake below or near the ocean floor. Unlike wind-driven waves, which only travel through the topmost layer of the ocean, tsunamis move through the entire water column, from the ocean floor to the ocean surface.

How are Tsunamis Formed

Earthquakes: According to the Global Historical Tsunami Database, since 1900, over 80% of likely tsunamis have been generated by earthquakes.
- When there is an earthquake, a large and sudden ocean floor displacement occurs, displacing a large volume of water above.
- E.g., 2004 Indian Ocean Tsunami resulted from the Sumatran-Andaman Earthquake.
Volcanic Eruptions: Tsunami waves may be generated by the sudden displacement of water caused by a volcanic explosion, by a volcano’s slope failure, or by a phreatomagmatic explosion and collapse/engulfment of the volcanic magmatic chambers.
- E.g., 2018 Tsunami in Indonesia is believed to be caused by the eruption of Anak Krakatau volcano.
Submarine & Coastal Landslides: Sudden mass movement of sediments under the sea generates waves.
- Eg: 1958 Lituya Bay Tsunami (Alaska)

Where are they formed

Tsunamis can be generated in all of the world’s oceans, inland seas, and in any large body of water.
Areas are particularly prone to tsunamis:
- 78% Pacific Ocean (around the geologically active “Ring of Fire”)
- 9% Atlantic Ocean and Caribbean Sea
- 6% Mediterranean Sea
- 5% Indian Ocean
- 1% Other Seas
The highest percentage of tsunamis are generated off Japan (20%), followed by Russia (8%) and Indonesia (8%).

Impact of Tsunamis

Loss of life: Tsunamis can result in the loss of thousands of lives.
- E.g., in 2004, the Indian Ocean tsunami claimed the lives of over 230,000 people across 14 countries
Displacement: Eg: 2004 Indian Ocean Tsunami displaced 1.7 million people.
Environmental impact: The force of the waves can cause erosion, leading to the destruction of coastal habitats such as coral reefs and mangroves.
- The influx of saltwater into freshwater ecosystems can also contaminate drinking water sources and harm aquatic life.
- E.g., The 2011 tsunami in Japan caused a nuclear accident at the Fukushima Daiichi power plant, leading to radioactive contamination of the surrounding environment.
Economic consequences: The destruction of infrastructure, loss of businesses, and disruption of supply chains can result in billions of dollars in damages.
- E.g., the 2004 Indian Ocean tsunami caused an estimated $10 billion in damages to infrastructure and property.
Geopolitical/Strategic Risks: Tsunamis lead to disruption of global supply chains
- E.g., Japan 2011 affected the automobile and electronics industries.

Far-reaching humanitarian, economic, and environmental impacts of Tsunamis highlight the urgent need for robust early warning systems, resilient coastal planning, and community preparedness. Strengthening natural bio-shields like mangroves, investing in international cooperation, and integrating disaster risk reduction into development strategies are essential to minimize the catastrophic consequences of future tsunamis.