UPSC Mains 2025 General Studies I
Q. What are Tsunamis? How and where are they formed? What are their consequences? Explain with examples.
Introduction
A tsunami is a series of large ocean waves generated by the sudden displacement of water in seas or oceans, usually caused by underwater earthquakes, volcanic eruptions, or landslides. According to the National Oceanic and Atmospheric Administration, tsunami waves can travel across oceans at speeds of 700–800 km/h, causing widespread coastal destruction. One of the most devastating events was the 2004 Indian Ocean Tsunami, which killed over 230,000 people across 14 countries.
Formation of Tsunamis
- Underwater Earthquakes (Primary Cause)
Most tsunamis occur due to seismic activity along tectonic plate boundaries, where sudden vertical displacement of the seafloor pushes large volumes of water upward.
Where it occurs
- Mainly along subduction zones in the Pacific Ring of Fire.
Example
- The 2004 Indian Ocean Tsunami triggered by a 9.1 magnitude earthquake near Sumatra.
- Volcanic Eruptions
Explosive volcanic eruptions can displace ocean water and generate tsunamis.
Example
- The 2018 Sunda Strait Tsunami occurred due to the collapse of Anak Krakatau volcano in Indonesia.
- Underwater Landslides
Submarine landslides caused by earthquakes or volcanic activity can trigger tsunamis.
Example
- Coastal landslides in tectonically active regions such as Alaska have generated localized tsunamis.
Areas Prone to Tsunamis
- Pacific Ocean Basin
The majority of tsunamis occur in the Pacific Ocean, due to intense tectonic activity along the Pacific Ring of Fire.
Example
- The 2011 Tōhoku Tsunami in Japan caused massive destruction and triggered the Fukushima Nuclear Disaster.
- Indian Ocean Region
Though less frequent, the Indian Ocean region also faces tsunami risk due to tectonic plate interactions.
Example
- The 2004 Indian Ocean Tsunami affected India, Sri Lanka, Thailand, and Indonesia.
Consequences of Tsunamis
- Massive Loss of Life and Property
Tsunamis cause sudden flooding and destruction of coastal settlements.
Evidence
- The 2004 Indian Ocean Tsunami caused over 230,000 deaths.
Impact in India
- Severe damage in Tamil Nadu, Andhra Pradesh, and Andaman and Nicobar Islands.
- Environmental Damage
Tsunamis destroy coastal ecosystems such as mangroves, coral reefs, and wetlands.
Example
- Coral reefs and mangroves in the Andaman Sea were heavily damaged in 2004.
- Economic Losses
Damage to infrastructure, ports, tourism and fisheries can severely affect economies.
Example
- The 2011 Tōhoku Tsunami caused economic losses estimated at over $200 billion, making it one of the costliest disasters.
- Secondary Disasters
Tsunamis can trigger nuclear accidents, chemical spills and disease outbreaks.
Example
- The Fukushima Nuclear Disaster following the 2011 Tōhoku Tsunami.
Disaster Management and Preparedness
After the 2004 disaster, India established the Indian National Centre for Ocean Information Services (INCOIS) tsunami warning system in Hyderabad to provide early warnings across the Indian Ocean region.
Conclusion
Tsunamis are among the most destructive natural hazards, capable of causing catastrophic human and economic losses. Strengthening early warning systems, coastal zone management, and disaster preparedness, as recommended by institutions like Indian National Centre for Ocean Information Services, is essential to minimize future impacts, particularly for vulnerable coastal populations.