On December 2004, tsunami brought havoc on fourteen countries including India. Discuss the factors…

Question

On December 2004, tsunami brought havoc on fourteen countries including India. Discuss the factors responsible for occurrence of tsunami and its effects on life and economy. In the light of guidelines of NDMA (2010) describe the mechanisms for preparedness to reduce the risk during such events.

Ghissu Editorial · Accepted Answer

Tsunamis arise mainly from shallow undersea megathrust earthquakes, magnified by shallow shelves and lost mangroves, and the 2004 waves devastated lives, fisheries and coastal land. The NDMA's 2010 guidelines rest on the INCOIS early warning centre, inundation mapping, safe structures, bio-shields and community drills.

**Introduction**

The 26 December 2004 tsunami, set off by a magnitude 9.1 quake off Sumatra, killed about 2.3 lakh people in fourteen countries, over 10,000 of them in India, and led to the NDMA's tsunami guidelines (2010).

**Factors Behind Tsunami Occurrence**

SKETCH: flow | How a tsunami forms
- Undersea megathrust quake
- Seafloor lifts suddenly
- Water column displaced
- Fast deep-ocean waves
- Waves rise near shore
- Coastal inundation

1. **Subduction earthquakes**: A shallow quake with vertical seafloor movement, as along the Sunda-Andaman trench in 2004, displaces the water column.
2. **Other triggers**: Submarine landslides and volcanic eruptions such as Hunga Tonga (2022) can also generate tsunamis.
3. **Coastal amplifiers**: Shallow shelves, flat coasts and lost mangroves, as at Nagapattinam, magnify the run-up.

**Effects on Life and Economy**

1. **Loss of life**: Nagapattinam alone lost about 6,000 people, and Andaman villages were washed away.
2. **Livelihoods and land**: Fishing boats and nets were wrecked for months, Cauvery delta farmland was salinised, the Car Nicobar air base was damaged and the Kalpakkam nuclear plant shut down.

**Preparedness Mechanisms under NDMA Guidelines (2010)**

1. **Early warning**: INCOIS's Tsunami Early Warning Centre (2007) uses seismic stations, bottom pressure recorders and tide gauges.
2. **Mapping and structures**: Inundation maps, Coastal Regulation Zone enforcement and tsunami-resistant lifeline buildings guide safe land use.
3. **Bio-shields and drills**: Mangroves, as at Pichavaram, and community evacuation drills protect people.

**Way Forward**

1. **Tsunami Ready coasts**: Extend Odisha's Venkatraipur and Noliasahi model (UNESCO-IOC, 2020) to every coast, carry alerts to fishers by cell broadcast, and rebuild buffers under the MISHTI mangrove mission.

**Conclusion**

Tsunamis cannot be prevented, but warning, mapping and drilled communities can keep a rare hazard from becoming a catastrophe, as the Sendai Framework seeks.

On December 2004, tsunami brought havoc on fourteen countries including India. Discuss the factors responsible for occurrence of tsunami and its effects on life and economy. In the light of guidelines of NDMA (2010) describe the mechanisms for preparedness to reduce the risk during such events.

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