# Q3A · Discuss in detail the causes and impacts of “Tamil Nadu Tsunami”. Also suggest any 4 …

Subject: Disaster Management

Exam: TEE

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Actual older TEE paper · 100 marks · Q1 compulsory; any four of Q2–Q7

### Q3A. Discuss in detail the causes and impacts of “Tamil Nadu Tsunami”. Also suggest any 4 measures of mitigation for reoccurrence of such disaster. [10 marks]

#### Answer

The **Tamil Nadu tsunami of 26 December 2004** was part of the Indian Ocean tsunami generated by the Sumatra–Andaman earthquake. Nagapattinam was especially badly affected; other severely affected coastal districts included Cuddalore, Kanyakumari and Chennai.

## 1. Causes: how the waves reached Tamil Nadu

1. **Undersea earthquake.** Sudden slip on the subduction boundary between the India plate and Burma microplate displaced the seafloor. The main trigger was this earthquake, not a cyclone or ordinary high tide.
2. **Displacement and propagation of seawater.** Vertical seafloor movement displaced the water above it. Long waves carried that disturbance across the Indian Ocean towards exposed coasts, including Tamil Nadu.
3. **Coastal inundation and vulnerability.** As the waves approached shallow coastal water, their interaction with coastal shape and depth produced destructive inundation and currents. Low-lying settlements, vulnerable housing and inadequate warning/evacuation readiness increased the losses; these conditions worsened the disaster but did not cause the earthquake.

Swipe across the diagram to read its labels ↔

![Tsunami: displacement → propagation → inundation](https://deep-learning-study-room.vercel.app/dm/fig/tsunami.bc017e1e08.svg)

Diagram: Tsunami: displacement → propagation → inundation. Labels: Tsunami: displacement → propagation → inundation | Tsunami: displacement → propagation → inundation | 1 · Seafloor displacement | 2 · Waves propagate | 3 · Move to designated | safe high ground | The tsunami can be a series of waves; do not return after the first wave.

Earthquake → seafloor and water displacement → travelling waves → coastal inundation. The drawing explains the mechanism; it is not a map of Tamil Nadu.

## 2. Impacts in Tamil Nadu

1. **Loss of life and family disruption.** Nagapattinam and other affected coastal districts suffered deaths, injuries and separation or loss of family members. Women, children and people unable to escape faced serious vulnerability.
2. **Housing loss and displacement.** Waves damaged or destroyed coastal houses and belongings. Families needed temporary shelter, safe water, sanitation and later permanent housing.
3. **Fishing and connected livelihoods.** Damaged boats, nets, landing and harbour facilities interrupted fishing. Fish sellers, processors and other workers dependent on the coastal fishing economy also lost income.
4. **Damage to services and productive assets.** Roads, power and other community facilities were damaged, complicating relief and recovery. Loss of livestock and other household assets further weakened livelihoods.

**Real recovery connection:** Tamil Nadu’s tsunami rehabilitation programmes included housing and infrastructure reconstruction and livelihood support. This shows why recovery had to restore both physical assets and the means of earning a living.

## 3. Four measures to reduce losses in a future tsunami

1. **Monitoring linked to usable warnings.** Connect seismic/ocean monitoring and official tsunami alerts to local announcements, accessible messages and named action responsibilities. An alert helps only if exposed people receive it and know where to go.
2. **Evacuation planning and repeated drills.** Map inundation zones, mark routes to designated safe ground and practise assisted evacuation. Include fishers, visitors, children, older people and persons with disabilities; do not assume everyone can walk the same distance or understand one language.
3. **Safer coastal land use and shelter locations.** Use hazard maps to guide new development and locate essential facilities outside high-risk areas. Where needed, properly engineered designated evacuation structures can complement safe routes; an ordinary coastal building is not automatically a safe refuge.
4. **Resilient reconstruction and protected lifelines.** Rebuild houses and public facilities using risk-informed siting and suitable standards; provide backup water, communications and access. Restore fishing and other livelihoods without recreating the same avoidable exposure.

**Meaning of “mitigation for reoccurrence”:** these measures reduce deaths, damage and disruption when another tsunami occurs. They cannot prevent the tectonic earthquake or guarantee that no tsunami will recur.

Case facts: [USGS: 2004 tsunami mechanism](https://www.usgs.gov/centers/pcmsc/science/tsunami-generation-2004-m91-sumatra-andaman-earthquake); [NIDM: Tamil Nadu case study, pp. 43–48](https://nidm.gov.in/pdf/modules/gender.pdf); [Tamil Nadu rehabilitation programmes](https://tnrd.tn.gov.in/schemes/ext_tsunami.html).

#### Real case and learning connection · Indian Ocean tsunami, 2004

The 2004 Indian Ocean tsunami shows how a large undersea disturbance can create destructive coastal waves. It also illustrates why coastal risk knowledge, detection, clear warnings and evacuation capability must work together; a monitoring instrument alone cannot move people to safety.