On December 2004, the tsunami wreaked havoc on 14 countries, including India. Discuss the factors responsible for the occurrence of a tsunami and its effects on life and the economy. In the light of NDMA guidelines (2010), describe the mechanisms for preparedness to reduce the risk during such events.
Subtopic: Disaster Management · Coastal hazards & tsunami early warning
How to structure your answer
Introduction: Define a tsunami (a series of long ocean waves triggered by sudden displacement of the seabed) and anchor on the 2004 Indian Ocean event.
Body: (1) Causal factors — submarine earthquakes, volcanism, landslides; (2) Effects on life and economy; (3) Preparedness mechanisms under the NDMA Tsunami Risk Management Guidelines (2010) — ITEWC at INCOIS, dissemination chain, response forces, bio-shields.
Conclusion: Balance the early-warning success with last-mile gaps and a forward line on community drills.
Written within the word limit
257 words · target 250 words · 11 min
Introduction: A tsunami is a series of long-wavelength ocean waves caused by the sudden vertical displacement of the seabed. The 26 December 2004 Sumatra event, born of a magnitude-9.1 undersea earthquake, killed over 2.2 lakh people across 14 nations and struck India's Tamil Nadu, Andhra, Kerala and Andaman coasts.
Causal factors: Most tsunamis arise from shallow-focus submarine earthquakes along subduction zones, where one plate thrusts under another and lifts the water column. Secondary triggers include underwater volcanic eruptions (Krakatoa, 1883), submarine landslides, and rarely meteorite impacts. The Andaman-Sumatra trench in the east and the Makran trench off the west make both Indian coastlines tsunamigenic.
Effects on life and economy: Mass casualties from drowning and debris, destruction of fishing fleets and harbours, salination of farmland and drinking-water aquifers, damage to ports, power and tourism, and long-term displacement of coastal communities. India's 2004 loss ran into thousands of crores, with Nagapattinam and the Andaman & Nicobar Islands worst hit.
Preparedness under the 2010 guidelines:
- The Indian Tsunami Early Warning Centre at INCOIS, Hyderabad detects tsunamigenic quakes within minutes using a seismic network, deep-ocean bottom-pressure recorders and coastal tide gauges.
- Advisories flow to NDMA, State and District authorities via SMS, fax, GTS and sirens for swift evacuation.
- NDRF battalions are pre-positioned in coastal and island regions, with mangrove and shelterbelt bio-shields, hazard mapping and community capacity-building.
Conclusion: The warning system is world-class, but the weak link remains the last mile — reaching fishermen at sea and isolated hamlets. Regular community mock drills and UNESCO's TsunamiReady recognition of coastal villages must close that gap to turn warning into safe response.
What an examiner expects to see
- Tsunami = series of long ocean waves from sudden seabed displacement; 2004 source was a magnitude-9.1 quake off Sumatra
- Primary cause is shallow-focus submarine earthquakes at subduction zones; secondary causes are volcanism, submarine landslides, meteorite impact
- Andaman-Sumatra trench (east) and Makran subduction zone (west) expose Indian coasts
- Indian Tsunami Early Warning Centre (ITEWC) set up at INCOIS, Hyderabad under Ministry of Earth Sciences, operational since October 2007
- ITEWC detects tsunamigenic earthquakes within minutes and disseminates advisories to NDMA, SDMAs and DDMAs
- Warning infrastructure includes seismic network, deep-ocean bottom-pressure recorders (buoys) and coastal tide gauges
- NDMA Tsunami Risk Management Guidelines (2010) cover risk assessment, early warning, mitigation, response and capacity building
- Mangroves and shelterbelts act as natural bio-shields; NDRF battalions stationed in coastal and island regions
- Economic effects: loss of fishing fleets, port and tourism damage, salination of farmland and groundwater
Concrete cases, schemes and judgments
- 26 December 2004 Indian Ocean tsunami (over 2.2 lakh deaths across 14 countries)
- Indian Tsunami Early Warning Centre (ITEWC) at INCOIS, Hyderabad
- 1883 Krakatoa volcanic-eruption tsunami
- UNESCO-IOC TsunamiReady recognition of Indian coastal villages (Odisha, A&N)
- Andaman-Sumatra subduction zone and Makran trench