A tsunami is a series of large sea waves generated mainly by sudden displacement of ocean water due to undersea earthquakes, volcanic eruptions, submarine landslides or meteorite impacts.

The word tsunami means “harbour wave”. Unlike ordinary sea waves caused by wind, tsunamis are caused by large-scale disturbance of the ocean floor. They can travel across oceans at very high speed and become extremely destructive when they reach shallow coastal areas.

India became highly conscious of tsunami risk after the 2004 Indian Ocean Tsunami, which severely affected the Andaman and Nicobar Islands and parts of the eastern coast of India.

Causes of Tsunami

Undersea Earthquakes
- Most tsunamis are caused by powerful undersea earthquakes.
- When the ocean floor is suddenly uplifted or displaced, a large volume of seawater is disturbed.
- This generates tsunami waves that travel outward in all directions.
Volcanic Eruptions
- Underwater or coastal volcanic eruptions can displace seawater and generate tsunami waves.
- Volcanic island collapse can also trigger tsunamis.
Submarine Landslides
- Large landslides under the sea can suddenly push water upward and generate waves.
- These may be localised but highly destructive near the coast.
Coastal Landslides
- Large landslides falling into the sea from coastal cliffs or islands can also create tsunami-like waves.
Meteorite Impact
- Though rare, large meteorites, asteroids, and comets falling into the ocean can displace water and generate tsunami waves.

Tsunami Vulnerability in India

India’s tsunami vulnerability is mainly linked to its long coastline, island territories, coastal population and proximity to active seismic zones in the Indian Ocean.
- Both the east and west coasts of India and the island regions are likely to be affected by tsunamis from the five potential source regions, viz., the Andaman-NicobarSumatra island arc, Indo-Burmese zone, Nascent Boundary (in the central Indian Ocean), Chagos archipelago and the Makran subduction zone.

Impact of Tsunami

Human Impact
- Tsunamis can cause sudden deaths, injuries, missing persons, displacement and psychological trauma.
- People near beaches, fishing areas, ports and low-lying coastal settlements are at high risk.
Infrastructure Impact
- Tsunamis damage houses, roads, bridges, ports, harbours, fishing boats, power lines, communication networks, schools, hospitals and tourist infrastructure.
- Coastal lifeline infrastructure may become non-functional.
Livelihood Impact
- Fisherfolk are severely affected due to loss of boats, nets, landing centres, fish markets and coastal assets.
- Tourism, small trade, salt production, coastal agriculture and port-related activities may also suffer.
Agricultural Impact
- Seawater inundation causes salinisation of agricultural land.
- Crops are damaged, soil fertility declines and groundwater becomes saline.
- Recovery of agricultural land may take time.
Environmental Impact
- Tsunamis damage mangroves, coral reefs, beaches, sand dunes, coastal wetlands and turtle nesting sites.
- They may also spread debris, sewage, chemicals, oil and waste into coastal ecosystems.
Health Impact
- Tsunamis can contaminate drinking water sources with saltwater, sewage and debris.
- Risks include injuries, infections, diarrhoea, skin diseases, mental trauma and lack of access to healthcare.
Social Impact
- Tsunamis disrupt families, education, housing, community life and social networks.
- Relocation of coastal communities may create cultural, livelihood and social adjustment problems.

Tsunami Disaster Risk Reduction Measures

Tsunami risk reduction focuses on reducing loss of life, minimising damage to coastal infrastructure and improving preparedness before tsunami waves reach the coast. Since tsunamis cannot be prevented, the main focus should be on early warning, evacuation, coastal planning and community awareness.

Tsunami Early Warning System
- A strong tsunami early warning system is the most important risk reduction measure.
- It should include seismic monitoring, ocean buoys, tide gauges, satellite communication, tsunami modelling and rapid alert dissemination.
- Early warning helps authorities evacuate people from low-lying coastal areas before tsunami waves arrive.
Coastal Hazard Mapping
- Tsunami-prone areas should be scientifically mapped.
- Hazard maps should identify tsunami inundation zones, low-lying coastal settlements, beaches, ports, tourist areas, fishing villages, evacuation routes, safe shelters and critical infrastructure at risk.
- This helps in advance planning and targeted preparedness.
Evacuation Planning
- Every tsunami-prone coastal settlement should have a clear evacuation plan.
- The plan should identify safe evacuation routes, higher ground, vertical evacuation buildings, tsunami shelters, transport needs, vulnerable households and emergency assembly points.
- Evacuation routes should be clearly marked and regularly maintained.
Last-Mile Warning Communication
- Warnings must reach the last person quickly.
- Alerts should be sent through SMS, sirens, radio, television, mobile apps, satellite communication, public announcement systems, coastal police, panchayats, local volunteers and fishermen communication networks.
- The warning should be simple, local-language based and action-oriented.
Community Awareness
- People should be trained to recognise natural tsunami warning signs.
- These include strong coastal earthquakes, sudden withdrawal of seawater, unusual roaring sound from the sea and sudden rise or fall of sea level.
- People should know that after such signs, they must move immediately to higher ground without waiting for official confirmation.
Mock Drills
- Regular tsunami mock drills should be conducted in coastal villages, schools, ports, tourist beaches and island settlements.
- Mock drills reduce panic, test evacuation routes and improve coordination among local authorities, police, volunteers and disaster response teams.
Coastal Land-Use Regulation
- Construction should be restricted in high-risk low-lying coastal zones.
- Tsunami inundation maps and coastal hazard lines should guide land-use planning.
- Settlements, hotels, industries and critical infrastructure should not be allowed in highly vulnerable areas without proper safety measures.
Tsunami Shelters and Vertical Evacuation Structures
- Tsunami shelters should be built in vulnerable coastal areas where high ground is not nearby.
- Multi-purpose cyclone-cum-tsunami shelters, raised platforms and strong vertical evacuation buildings can save lives.
- These shelters should be accessible, clearly marked and connected with safe routes.
Resilient Coastal Infrastructure
- Critical infrastructure should be designed to withstand coastal flooding and wave impact.
- Ports, harbours, hospitals, schools, roads, bridges, power systems, communication towers and emergency centres should be made disaster-resilient.
Ecosystem-Based Protection
- Natural ecosystems reduce tsunami impact by absorbing wave energy.
- Mangroves, coral reefs, sand dunes, coastal wetlands and shelterbelts should be protected and restored.
- These natural buffers cannot stop a major tsunami completely, but they can reduce wave force and coastal damage.
Safety of Fisherfolk
- Fisherfolk are highly vulnerable because their livelihood depends on the sea.
- They should receive timely marine advisories through communication devices, harbour warning systems, radio networks, mobile alerts and coastal control rooms.
- Fishing boats should have communication equipment and safe-return protocols.
Tourist Safety
- Tourist beaches should have tsunami warning boards, evacuation maps, public announcement systems, trained lifeguards and clearly marked safe zones.
- Tourists may not know local risks, so visible signage and awareness are important.
School and Institutional Preparedness
- Schools, colleges, hospitals, hotels and public institutions in coastal areas should have tsunami preparedness plans.
- They should conduct regular drills, maintain emergency kits and train staff in evacuation and first aid.
Capacity Building
- Local officials, police, teachers, health workers, community volunteers, fisherfolk groups and panchayats should be trained in tsunami preparedness.
- Training should cover warning interpretation, evacuation, first aid, shelter management, search and rescue and relief coordination.
Integration with Coastal Zone Management
- Tsunami risk reduction should be integrated with Integrated Coastal Zone Management.
- Coastal development should balance livelihood needs, ecological protection, disaster risk reduction and safe infrastructure planning.
Insurance and Livelihood Protection
- Tsunamis can destroy boats, nets, houses, shops, crops and coastal assets.
- Insurance, livelihood support, emergency credit and post-disaster compensation can help affected communities recover faster.
Build Back Better
- Post-tsunami reconstruction should not recreate earlier vulnerabilities.
- Houses, roads, shelters, ports and public buildings should be rebuilt in safer locations with better design.
- Where necessary, relocation from highly exposed coastal areas should be done with proper livelihood support.

Challenges in Tsunami Management in India

Short Warning Time for Islands
- Andaman and Nicobar Islands are close to tsunami-generating seismic zones.
  - Near-field tsunamis (Andaman zone) — lead time of 7 minutes insufficient for mass evacuation of dense coastal settlements
- This gives very little time for official warning and evacuation.
Last-Mile Communication Gaps
- Warnings may not reach remote islands, fisherfolk at sea, tourists, coastal villages and vulnerable groups in time.
  - Last-mile warning failure — power cuts during earthquakes disable sirens; fisher communities at sea unreachable
Low Public Awareness
- Many people may not recognise natural warning signs such as sudden sea withdrawal or strong coastal earthquakes.
- This can delay evacuation.
Unplanned Coastal Development
- Hotels, houses, ports, roads and settlements are often located close to the shoreline.
- Coastal Regulation Zone (CRZ) dilution — commercial pressure on coastal construction weakens natural buffer zones
- This increases exposure to tsunami waves.
Vulnerability of Fisherfolk
- Fishing communities live close to the sea and depend on marine livelihoods.
- They may lose lives, boats, nets, houses and markets during tsunamis.
Difficulty in Evacuation
- Low-lying coastal areas, islands, elderly population, children, persons with disabilities, tourists and congested settlements make evacuation difficult.
Weak Maintenance of Shelters and Routes
- Evacuation routes, signboards, sirens and shelters are not regularly maintained.
- During emergencies, this can create confusion.
Ecosystem Degradation
- Destruction of mangroves, coral reefs, dunes and wetlands reduces natural coastal protection.
Multi-Hazard Nature
- Tsunamis may occur along with earthquakes, aftershocks, coastal flooding, erosion, salinisation, fires and disease risks.
- This makes the response more complex.
Disaster amnesia — 20 years since 2004; community preparedness and drill participation declining
No dedicated Tsunami-Resistant Building Code — CRZ restricts location but not construction quality

NDMA Guidelines

Tsunami Hazard Assessment
- The assessment of vulnerability and risk and mapping in the tsunami hazard area must be carried out taking the various other hazards as applicable.
  - Many of the areas prone to tsunamis are also prone to storm surges caused by tropical cyclones. Hence, a multihazard approach will have to be followed for addressing the preparedness, mitigation and emergency response requirements in the coastal areas.
Tsunami Vulnerability Assessment
- The vulnerability assessment of both built and natural environments due to tsunami impact will be developed for shores and harbours by the Ministry Of Earth Sciences .
Mitigation Measures
- Need for New Standards for Protection of Structures against Tsunami
  - There is a need to identify tsunami resilient construction practices and ensure their strict compliance.
  - Several premier research institutes of the country, particularly a few IITs and SERC have carried out research studies on cyclone-resistant designs and construction of disaster-resilient structures. Along similar lines, there is an urgent need to carry out research studies on tsunami-resistant construction practices for the tsunami-prone coastal areas.
- Shelters for Storm Surges and Tsunamis
  - On receiving a Tsunami Warning, evacuation of the population would be required by the local authority. Safe evacuation will be carried out to cyclone- cum-tsunami shelters along the coast.
  - Cyclone-cum-tsunami shelters should be designed in such a way that they address multi-purpose uses. Such multi-purpose uses will ensure that such structures do not fall into disuse when there is no threat of cyclones or tsunamis. This would ensure their proper maintenance by the community itself. Cyclonecum-tsunami shelters should be so designed so as to take care of the livestock of the communities, wherever possible, while protecting the local people
- Institutionalisation of Design and Construction for Tsunami Safety
  - It is necessary that the tsunami risk and vulnerability of the coastal areas is taken into consideration while designing buildings and other structures in tsunami and cyclone-prone coastal areas. In the design of public infrastructure like roads, schools, hospitals, multi-purpose shelters etc., prevailing risk and vulnerability has to be kept in mind. In tsunamiprone areas, the DDMAs will ensure that a bank of designs of temporary shelters, intermediate shelters and disaster-resilient houses shall be prepared, with the flexibility to use traditional and local knowledge, coping capacities and locally available shelter materials.
- Tsunami Mitigation Measures
  - Construction of large scale submerged sand barriers in water depths of about 6 to 8 meters.
  - Developing sand dunes along the coast with sea weeds or shrubs or casuarinas trees for stabilization of the sand dunes.
  - Establishment of mangrove plantations (as a coastal defence against Tsunami) for communities residing along the estuaries.
  - keeping the village area free from debris (for example discarded construction material, automobiles and other similar loose materials) as they may have adverse impact during runup or run-down associated with Tsunami.
  - Construction of Tsunami shelters (supported by circular RCC columns) on a raised ground (3m above the ground level) in high tsunami-risk villages
  - Raising the ground level (above the design water level) with natural beach sand so as to rehabilitate the entire coastal village.
  - Development of coastal forest (green belt) by planting casuarinas or coconut trees along the coastline to cover a minimum of about 500m width of the beach.
  - Periodical dredging of the inlets and associated water bodies so as to absorb the influx during Tsunami.
  - Construction of submerged dykes (one or two rows along the stretch of the coast) so as to decrease the impact due to the incoming tsunami.
  - Construction of elevated hutments supported on piles or hardened podiums to allow tsunami run-up to escape beneath the structure.
  - Positioning stationary platforms in the backwaters for evacuating the public during tsunami.
  - Adopting natural beach nourishment to create a steep beach face.
  - Construction of concrete defence structures to protect installations of national importance stationed on the coast.
  - Vertical evacuation structures in all harbours.
  - Construction of inland dykes to safeguard vital installations.
Awareness
- Comprehensive public awareness campaigns will be developed and launched at the national, state and district levels, especially in high risk areas for familiarisation with the tsunami warning dissemination mechanism and responsibilities of various stakeholder groups.
  - SDMAs/DDMAs will conduct regular public awareness campaigns for familiarising communities in coastal areas with the tsunami early warning mechanisms through workshops, drills and exercises, screening of video films, distribution of information resources, posters etc. Handbooks and instructional materials, in vernacular languages, will be prepared by SDMAs for creating greater awareness among the communities on tsunami risk and vulnerability.
  - State Governments and SDMAs in collaboration with their SEMCs, HSCs and nongovernmental organisations (NGOs) will organise awareness programmes for specific target groups of stakeholders on various aspects of tsunami management. These stakeholders will include elected representatives and civil servants, members of local administration authorities and others like school administrators, members of management boards of educational institutions and hospitals, school children, representatives of the corporate sector, media, etc.
Education
- State Governments must endeavour to strengthen tsunami education by incorporating the best available technical and non-technical inputs on tsunami safety in educational curricula. Tsunami education will address the multifaceted aspects of tsunami management, especially preparedness, mitigation and response efforts

Way Forward

Strengthen tsunami early warning systems with better seismic sensors, ocean buoys, tide gauges, modelling and real-time communication.
- Expand DART buoy network in Andaman Sea
Ensure last-mile alert dissemination through sirens, SMS, mobile apps, radio, satellite communication, coastal police, panchayats and community volunteers.
- Integrate cell broadcasting (like Japan’s J-Alert) — automatic SMS to all phones in warning zone without network dependency
Prepare tsunami inundation maps for vulnerable coastal areas and islands.
- Develop Tsunami Inundation Maps for all 13 coastal states & UTs — publicly available, integrated with DM plans
Integrate tsunami risk into coastal land-use planning, CRZ regulation and infrastructure development.
- Strengthen CRZ enforcement — resist commercial dilution; no-build zones are the cheapest disaster insurance
Conduct regular mock drills in coastal villages, schools, ports, tourist beaches and island settlements.
- Annual IOWave drills extended to sub-district level — every coastal Gram Panchayat participates
Mandatory vertical evacuation structures in all coastal towns with population >10,000
Build and maintain tsunami shelters, evacuation roads, signboards and vertical evacuation structures.
Train local communities, fisherfolk, hotel staff, school teachers and local officials in tsunami preparedness.
Develop special communication systems for fisherfolk at sea.
Protect and restore mangroves, coral reefs, sand dunes, shelterbelts and coastal wetlands.
- Scale mangrove restoration under MISHTI scheme (Mangrove Initiative for Shoreline Habitats & Tangible Incomes) — launched 2023
Make coastal infrastructure disaster-resilient, especially ports, hospitals, schools, power systems and communication networks.
Promote disaster insurance and livelihood recovery support for coastal communities.
Ensure post-tsunami rehabilitation follows the principle of Build Back Better.
International cooperation — strengthen UNESCO-IOC Indian Ocean Tsunami Warning System; share real-time data with SAARC nations

Tsunamis are low-frequency but high-impact disasters. India’s tsunami vulnerability is highest in the Andaman and Nicobar Islands and parts of the eastern coast due to proximity to active undersea seismic zones and dense coastal settlements. Since tsunamis cannot be prevented, disaster management must focus on early warning, quick evacuation, coastal hazard mapping, community awareness, resilient infrastructure, ecosystem protection and last-mile communication. A people-centric and preparedness-based approach can greatly reduce loss of life and long-term damage.

Sample Mains Questions

Q1. What is a tsunami? Explain the major causes of tsunamis.
(150 words, 10 marks)

Q2. Discuss India’s vulnerability to tsunamis with reference to its coastal and island regions.
(150 words, 10 marks)

Q3. Tsunamis are low-frequency but high-impact disasters. Analyse.
(150 words, 10 marks)

Q4. Explain the role of tsunami early warning systems and evacuation planning in reducing loss of life.
(250 words, 15 marks)

Q5. Discuss the major challenges in tsunami management in India. Suggest suitable measures.
(250 words, 15 marks)

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