Earthquakes and Tsunamis

Earthquakes and Tsunamis

What the topic is and why it matters for UPSC

Earthquakes are sudden releases of elastic strain energy in the Earth’s lithosphere that generate seismic waves, while tsunamis are long‑period ocean waves triggered primarily by under‑sea earthquakes, volcanic eruptions, or landslides. Both phenomena are natural hazards of high‑impact magnitude, capable of causing massive loss of life, crippling infrastructure, and triggering secondary crises such as disease outbreaks, displacement, and economic disruption.

For a civil servant, understanding these hazards is essential because:

• Disaster management – The Ministry of Home Affairs (MHA) and the National Disaster Management Authority (NDMA) formulate policies, early‑warning systems, and response mechanisms that hinge on scientific knowledge of seismic and tsunami behaviour.
• Infrastructure planning – Building codes, land‑use zoning, and coastal‑development regulations must incorporate seismic risk assessments to ensure resilience.
• International obligations – India is a signatory to the Sendai Framework for Disaster Risk Reduction and the UN Convention on the Law of the Sea (UNCLOS), both of which demand robust national capacities for earthquake‑ and tsunami‑risk mitigation.
• Socio‑economic impact – Large‑scale events reshape demographic patterns, affect agricultural output, and strain fiscal resources, influencing policy decisions across ministries.

Constitutional / Legal foundation

The State’s duty to protect life and liberty under Article 21 of the Constitution, interpreted by the Supreme Court to include the right to a safe and healthy environment, underpins disaster‑risk legislation. The Disaster Management Act, 2005 and the National Disaster Management Policy, 2009 provide the statutory framework for preparedness, mitigation, and response to earthquakes and tsunamis.

Sub‑topics covered in this chapter

1. Fundamentals of Seismology – tectonic plates, fault types, focus & epicentre, seismic waves (P, S, surface).
2. Measurement & Classification – Richter magnitude, moment magnitude (Mw), Mercalli intensity, seismic hazard maps.
3. Earthquake‑prone Zones in India – Himalayan belt, Indo‑Gangetic plain, Western Ghats, Andaman‑Nicobar, Northeast.
4. Causes & Triggers – natural (tectonic, volcanic) vs. induced (reservoir‑induced, mining, hydraulic fracturing).
5. Tsunami Generation & Propagation – plate subduction, seafloor displacement, wave dynamics, run‑up.
6. Historical Indian Events – 2001 Bhuj (M Mw 7.7), 2004 Indian Ocean tsunami, 2015 Nepal quake, 2021 Ladakh tremor, 2023 Odisha tsunami‑like surge.
7. Early‑warning Systems & Technology – seismograph networks (IMD, NGRI), Tsunami Early Warning Centre (TEWS), GIS‑based risk mapping, crowd‑sourced alerts.
8. Building Codes & Engineering Measures – IS 1893, IS 4326, base isolation, retrofitting, land‑use zoning.
9. Disaster Management Architecture – roles of NDMA, State Disaster Management Authorities (SDMAs), District Disaster Management Authorities (DDMAs), community participation.
10. Mitigation, Preparedness & Post‑disaster Recovery – evacuation drills, public awareness, insurance schemes, rehabilitation policies.

Exam relevance

A solid grasp of earthquakes and tsunamis not only secures marks in the Geography and Environment sections but also equips future administrators to design resilient policies, coordinate multi‑agency responses, and safeguard lives and livelihoods.

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