The 2004 Indian Ocean Tsunami highlighted the devastating power of these ocean waves, killing over 230,000 people across 14 countries and emphasizing the urgent need for global tsunami preparedness.

What are Tsunamis?

Tsunamis are series of ocean waves generated by sudden displacement of large water volumes, traveling at speeds of 500-800 km/hr in deep waters. Unlike regular waves caused by wind, tsunamis involve entire water columns from surface to seabed.

How and Where are Tsunamis Formed?

Causes of Tsunamis

Mechanism of a Tsunami

• Seafloor Disturbance: A strong undersea earthquake, volcanic eruption, or landslide causes sudden vertical displacement of the seabed.
• Water Column Displacement: This movement pushes or pulls a massive volume of water above, disturbing the ocean’s surface.
• Wave Propagation: Energy travels outward in the form of long, fast-moving waves (up to 800 km/h) across the deep ocean with low height.
• Shoaling and Coastal Impact: As waves enter shallow coastal waters, they slow down and grow in height dramatically, resulting in giant, destructive waves that flood coastal areas.
  

  Tsunami Wave Formation

Formation Locations

• Pacific Ring of Fire: 80% of global tsunamis occur here
• Subduction Zones: Andaman, Makran, and Java trenches
• Volcanic Islands: Indonesia, Philippines, Japan
• Transform Fault Lines: California coast, Mediterranean Sea
• Continental Margins: Areas with steep underwater topography

Consequences of Tsunamis

Immediate Impacts

• Human Casualties: 2004 tsunami killed 230,000+ people across Indian Ocean
• Infrastructure Destruction: 2011 Japan tsunami caused $235 billion in damages
• Coastal Inundation: Waves reaching 40 meters height in Japan (2011)
• Nuclear Disasters: Fukushima Daiichi meltdown triggered by tsunami
• Port Disruption: Major shipping routes and fishing industries paralyzed

Long-term Consequences

• Environmental Degradation: Saltwater intrusion affecting agriculture for years
• Economic Disruption: Tourism losses in Thailand and Sri Lanka post-2004
• Social Displacement: 160,000 people still displaced in Japan (2011)
• Groundwater Contamination: Coastal aquifers affected by saltwater
• Ecosystem Damage: Coral reefs and mangrove destruction

IOWave23 exercises and Indian Ocean Tsunami Warning System demonstrate international cooperation in building resilient coastal communities through early warning systems and disaster preparedness.