What are Tsunamis? How and Where are they formed? What are their consequences? Explain with examples. (150 words) upsc mains 2025 gs1 model answers

What are Tsunamis? How and Where are they formed? What are their consequences? Explain with examples. (150 words)

A Tsunami is a series of large, long-wavelength sea waves caused by the sudden displacement of a large volume of water, usually due to undersea seismic activity. The term comes from the Japanese words “tsu” (harbor) and “nami” (wave).

Formation (How):

• Seismic Activity: Most tsunamis originate from undersea earthquakes (magnitude >7.0) causing vertical displacement of the ocean floor.
• Other Causes:
• Volcanic eruptions (e.g., Krakatoa, 1883).
• Submarine landslides.
• Glacial calving or meteorite impacts.
• Process: Displaced water propagates as high-speed waves (600–800 km/hr). In deep oceans, they are barely noticeable, but on reaching shallow coastal waters, they rise to great heights (10–30 m).

Geographical Distribution (Where):

• Most common along Pacific “Ring of Fire” (Japan, Indonesia, Chile).
• Indian Ocean is also prone, though less frequent (e.g., Sumatra 2004).

Consequences:

1. Human Impact:
• Large-scale loss of life.
• The 2004 Indian Ocean Tsunami killed over 2.3 lakh people across 14 countries, including India’s Tamil Nadu and Andaman & Nicobar Islands.
2. Economic Impact:
• Destruction of infrastructure, ports, fisheries, and agriculture.
• Tourism decline (e.g., Phuket, Thailand after 2004).
3. Environmental Impact:
• Coastal erosion, salinization of soils and groundwater.
• Destruction of mangroves and coral reefs.

Conclusion:
Tsunamis are among the most destructive natural hazards. Effective early warning systems (INCOIS in India), coastal afforestation, and community preparedness are vital for reducing their catastrophic impacts.

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