43  Natural hazards and disasters: Mitigation strategies

43.1 What the Syllabus Covers

A hazard is a natural or human-made phenomenon that may cause damage. A disaster is the actual event in which the hazard causes serious disruption — loss of life, livelihood, or property — that exceeds local capacity to cope.

PYQs reliably ask: (a) define risk (Hazard × Vulnerability × Exposure ÷ Capacity), (b) name the type of natural hazard (geological, hydrological, meteorological, climatological, biological), (c) identify seismic zones of India (II/III/IV/V), (d) name India’s National Disaster Management Authority (NDMA, 2005) and acts, and (e) match the disaster to its year (Bhuj 2001, Indian Ocean Tsunami 26 Dec 2004, Kashmir 2005, Uttarakhand 2013, Nepal 2015, Kerala floods 2018, Joshimath 2023).

TipHazard vs Disaster
  • Hazard — the threat (an earthquake fault).
  • Disaster — the consequence when the hazard strikes vulnerable populations.
  • Risk = Hazard × Vulnerability × Exposure ÷ Capacity.

43.2 Classification of Hazards

TipFive Hazard Types (UNDRR)
Type Examples
Geological / Geophysical Earthquakes, volcanoes, tsunamis, landslides, avalanches
Hydrological Floods, flash floods, glacial lake outburst floods (GLOFs)
Meteorological Cyclones, tornadoes, hail, lightning
Climatological Heatwaves, cold waves, droughts, wildfires
Biological Epidemics (COVID-19, dengue, plague), pest invasions, locusts

Plus technological / human-induced hazards: industrial accidents (Bhopal), nuclear accidents (Chernobyl), oil spills, chemical leaks.

43.3 Earthquakes

TipEarthquake Vocabulary
  • Focus / Hypocentre — origin of rupture below ground.
  • Epicentre — point directly above focus on surface.
  • Magnitude — energy released (Richter scale, Moment Magnitude Mw).
  • Intensity — damage felt (Mercalli scale, I–XII).
  • P-waves (Primary, fast) → S-waves (Secondary, shear) → Surface waves (Rayleigh, Love).
  • Tsunami — sea wave from undersea quake.
  • Aftershocks — smaller quakes following main shock.

43.3.1 Seismic Zones of India

TipIndia’s 4 Seismic Zones (BIS, IS 1893)
  • Zone II — Low risk (parts of Karnataka, AP, MP, Rajasthan).
  • Zone III — Moderate risk (most of South India, central plateau).
  • Zone IV — High risk (NCR Delhi, parts of UP, Bihar, parts of Maharashtra, J&K, HP).
  • Zone V — Very high risk (NE India, Andaman & Nicobar, Bhuj region, parts of Uttarakhand, HP, J&K).

43.3.2 Major Indian Earthquakes

TipMajor Indian Earthquakes
Year Quake Magnitude Notes
1934 Bihar-Nepal 8.0 Killed ~10,700
1950 Assam (Medog-Rima) 8.6 One of the strongest ever
1991 Uttarkashi 6.8 Uttarakhand
1993 Latur (Maharashtra) 6.2 Killed ~10,000; intra-plate
1999 Chamoli (Uttarakhand) 6.8
2001 Bhuj (Gujarat) 7.7 ~20,000+ deaths; led to NDMA
2004 Indian Ocean Tsunami 9.1 (Sumatra) ~16,000 in India; 230,000+ across 14 countries
2005 Kashmir 7.6 Cross-border, ~80,000 deaths
2011 Sikkim 6.9
2015 Nepal-Gorkha 7.8 Affected NE India
2023 Türkiye-Syria (referenced) 7.8 —

43.3.3 Famous Global Earthquakes

TipMajor Global Quakes
  • Lisbon 1755 — pioneering seismology.
  • San Francisco 1906.
  • Chile 1960 — strongest recorded, Mw 9.5.
  • Alaska 1964 — Mw 9.2.
  • Sumatra 2004 — Mw 9.1, Indian Ocean tsunami.
  • Tōhoku, Japan 11 March 2011 — Mw 9.1, Fukushima.
  • Türkiye-Syria 2023.

43.4 Volcanoes

TipVolcano Facts
  • India: Barren Island, Andaman — only active volcano. Narcondam is dormant.
  • Pacific Ring of Fire has 75% of world’s volcanoes.
  • VEI (Volcanic Explosivity Index) 0-8.
  • Famous eruptions: Krakatoa 1883 · Mount St. Helens 1980 · Pinatubo 1991 · Eyjafjallajökull (Iceland) 2010 · Hunga Tonga 2022.

43.5 Tsunamis

TipTsunamis
  • Long-wavelength sea waves caused by undersea earthquakes, landslides, or volcanic eruptions.
  • Indian Ocean Tsunami, 26 December 2004 — triggered by Mw 9.1 Sumatra quake; ~230,000 deaths in 14 countries; ~16,000 deaths in India (Tamil Nadu, Andhra Pradesh, Kerala, A&N).
  • Indian Tsunami Early Warning System (INCOIS, Hyderabad) — established 2007.

43.6 Floods

TipFlood Types and Indian Cases
  • Riverine floods — Brahmaputra, Ganga, Mahanadi, Godavari, Krishna.
  • Flash floods — quick onset; common in Himalayan rivers (Kedarnath 2013, Joshimath/Chamoli 2021, Sikkim GLOF 2023).
  • Urban floods — Mumbai 2005, Chennai 2015, Bengaluru 2022.
  • GLOFs — Glacial Lake Outburst Floods (Kedarnath 2013, Sikkim 2023).
  • Coastal floods — storm surge from cyclones.
  • Kerala floods 2018 — worst in century, ~480 deaths.
  • Brahmaputra Board for flood management in NE.
  • Central Water Commission (CWC) — flood forecasting.

43.7 Cyclones

TipCyclones
  • Indian Ocean cyclones named by WMO/ESCAP Panel (Tropical Cyclone Naming List, 13 member countries).
  • Saffir-Simpson scale (1-5) used for Atlantic.
  • IMD scale for North Indian Ocean.
  • Twin cyclonic basins: Bay of Bengal (more active) and Arabian Sea.
  • Major Indian cyclones:
    • Odisha super cyclone 1999 — 10,000+ deaths.
    • Phailin 2013 — better forecasting saved lives.
    • Hudhud 2014 (Andhra).
    • Vardah 2016 (Chennai).
    • Fani 2019 (Odisha).
    • Amphan 2020 (West Bengal).
    • Tauktae 2021 (West Coast).
    • Yaas 2021 (Odisha/Bengal).
    • Biparjoy 2023 (Gujarat).
    • Remal 2024 (Bengal/Bangladesh).
  • IMD issues warnings 5 days in advance (color-coded).

43.8 Droughts

TipDrought Types
  • Meteorological — rainfall deficit > 25 %.
  • Hydrological — surface and groundwater depletion.
  • Agricultural — soil moisture deficit affecting crops.
  • Socio-economic — impact on people, livelihoods.

Indian drought-prone regions: Bundelkhand, Vidarbha, Marathwada, Telangana, Rayalaseema, Saurashtra, Kutch. Bundelkhand drought 2014-16 widely studied.

43.9 Landslides

TipLandslides
  • Movement of rock, debris, or earth down a slope.
  • Causes: rain, seismic activity, slope cutting, deforestation.
  • Indian landslide-prone regions: Western Ghats, Eastern Ghats, Himalayan ranges.
  • Notable: Malin (Maharashtra) 2014 · Kerala 2018 onwards · Wayanad (Kerala) 2024 · Joshimath subsidence 2023.
  • National Landslide Risk Management Strategy (2019) by NDMA.

43.10 Heatwaves and Cold Waves

TipHeatwaves and Cold Waves
  • Heatwave (IMD criteria): Temperature ≥ 40°C plains, ≥ 30°C hills, ≥ 37°C coastal, with deviation criteria.
  • Cold wave: below normal minimums in winter; severe in Northern India.
  • 2015 Andhra/Telangana heatwave killed 2,500+.
  • 2010 Ahmedabad heat — led to first South Asian Heat Action Plan (HAP).
  • 200+ Indian cities have HAPs now (Ahmedabad, Nagpur, Bhubaneswar, Surat).

43.11 Biological Hazards

TipBiological Hazards / Epidemics
  • Pandemics: Spanish flu 1918, H1N1 2009, COVID-19 2019-23.
  • Vector-borne: dengue, malaria, JE, kala-azar, chikungunya, Zika.
  • Locust swarms — Rajasthan 2020.
  • Avian influenza (H5N1) outbreaks.
  • Antimicrobial Resistance (AMR).
  • WHO IHR (2005) — International Health Regulations.
  • India’s NCDC (National Centre for Disease Control) — surveillance.

43.12 Disaster Management — Indian Institutional Framework

TipIndian DM Framework
  • Disaster Management Act, 2005 — passed after 2004 tsunami.
  • NDMA (National Disaster Management Authority, 2005) — apex, PM as chair, New Delhi.
  • NDRF (National Disaster Response Force, 2006) — operational force; 16 battalions; HQ Ghaziabad.
  • NIDM (National Institute of Disaster Management) — training & research.
  • SDMA / DDMA — state and district levels.
  • NDMA Guidelines for each hazard type.
  • National Cyclone Risk Mitigation Project (NCRMP).
  • National Flood Management Programme.
  • CDRI (Coalition for Disaster Resilient Infrastructure, 2019) — international, HQ New Delhi.
  • Aapda Mitra — community volunteers.
  • NDMA Heat Action Plan template.
  • IMD, INCOIS, CWC, GSI, NRSC — technical agencies.
  • SDRF — State Disaster Response Force.
  • Bhuvan / GIS for hazard maps.

43.13 Disaster Management Cycle and Strategies

43.13.1 The Cycle

TipDisaster Management Cycle

Mitigation → Preparedness → Response → Recovery (+ feedback into Mitigation).

Mitigation reduces risk before; preparedness builds capacity to act; response is the immediate action during/after; recovery restores function.

43.13.2 Mitigation Strategies

TipStructural and Non-Structural Mitigation
  • Structural: earthquake-resistant buildings (IS 1893, IS 4326, IS 13920); flood-control dams; seawalls; cyclone shelters; tsunami walls.
  • Non-structural: zoning, land-use planning, early-warning systems, insurance, community awareness, mock drills, education.
  • Building codes under National Building Code (NBC), Bureau of Indian Standards (BIS).
  • Climate-resilient infrastructure via CDRI.

43.13.3 Early-Warning Systems

TipEWS in India
  • IMD — meteorological (cyclones, heatwaves).
  • INCOIS, Hyderabad — ocean (tsunami, swell).
  • CWC — flood forecasting.
  • GSI — earthquakes, landslides.
  • NRSC, ISRO — satellite-based monitoring (Bhuvan).
  • Common Alerting Protocol (CAP) — SMS, app alerts.
  • Sachet App — disaster alerts (NDMA).

43.14 International Frameworks

TipInternational DRR Frameworks
  • Yokohama Strategy, 1994.
  • Hyogo Framework for Action (HFA, 2005-2015).
  • Sendai Framework for Disaster Risk Reduction (SFDRR, 2015-2030) — 4 priorities + 7 targets.
  • UNDRR (UN Office for Disaster Risk Reduction) — formerly UNISDR.
  • SDG 11 — Sustainable Cities; SDG 13 — Climate Action.
  • CDRI — Coalition for Disaster Resilient Infrastructure (India 2019).

43.14.1 Sendai 4 Priorities

TipSendai 4 Priorities
  1. Understanding disaster risk.
  2. Strengthening disaster risk governance.
  3. Investing in DRR for resilience.
  4. Enhancing preparedness for effective response, and building back better.

43.15 Theory Anchors

TipPersons, Bodies, Frameworks
Body / Event Note
Indian Ocean Tsunami 26 December 2004 (Sumatra Mw 9.1) — triggered India’s DM Act 2005
DM Act 2005 Passed in aftermath of tsunami
NDMA 2005 Apex DM body; New Delhi
NDRF 2006 16 battalions; HQ Ghaziabad
NIDM Training & research
IMD 1875; meteorology
INCOIS 1999; ocean
CWC 1945; water
GSI 1851; geology
NRSC / ISRO Satellite hazard maps
UNDRR / Sendai 2015 International DRR
CDRI 2019 India + global partners
Charles Richter 1935 Richter scale
Saffir & Simpson 1970s cyclone intensity scale

43.16 Practice Questions

Q 01 Definition Easy

The difference between a "hazard" and a "disaster" is:

  • AA hazard is real; a disaster is imagined
  • BA hazard is a threat; a disaster is the consequence when the hazard strikes vulnerable populations
  • CHazards are natural; disasters are man-made
  • DThere is no difference
View solution
Correct Option: B
Hazard = threat; Disaster = consequence. Risk = Hazard × Vulnerability × Exposure / Capacity.
Q 02 Indian Ocean Tsunami Medium

The Indian Ocean Tsunami struck on:

  • A26 January 2001
  • B26 December 2004
  • C11 March 2011
  • D25 April 2015
View solution
Correct Option: B
26 December 2004 — Sumatra Mw 9.1; ~230,000 deaths in 14 countries; led to India's DM Act 2005.
Q 03 NDMA Easy

India's National Disaster Management Authority (NDMA) was established in:

  • A2001
  • B2005
  • C2009
  • D2014
View solution
Correct Option: B
NDMA 2005, under DM Act 2005. PM chairs.
Q 04 Seismic Zones Medium

Which seismic zone in India represents the HIGHEST risk?

  • AZone II
  • BZone III
  • CZone IV
  • DZone V
View solution
Correct Option: D
Zone V — NE India, Andamans, Kutch, parts of Uttarakhand, J&K, HP.
Q 05 Earthquake Scale Hard

The Richter Scale measures the:

  • ADamage felt by people
  • BEnergy released by an earthquake
  • CDepth of focus only
  • DDistance from epicentre
View solution
Correct Option: B
Richter / Mw = magnitude (energy). Mercalli (I-XII) = intensity (damage felt).
Q 06 Bhuj Medium

The Bhuj earthquake of 26 January 2001 occurred in:

  • AMaharashtra
  • BGujarat
  • CUttarakhand
  • DSikkim
View solution
Correct Option: B
Bhuj, Gujarat, Mw 7.7, ~20,000 deaths. Republic Day morning.
Q 07 NDRF Medium

NDRF, India's operational disaster response force, has its headquarters at:

  • ANew Delhi
  • BGhaziabad
  • CPune
  • DHyderabad
View solution
Correct Option: B
NDRF HQ Ghaziabad, established 2006; 16 battalions.
Q 08 Tsunami EWS Hard

India's Tsunami Early Warning System is operated by:

  • AIMD
  • BINCOIS, Hyderabad
  • CCWC
  • DGSI
View solution
Correct Option: B
INCOIS (Indian National Centre for Ocean Information Services), Hyderabad. 2007.
Q 09 Cyclone Medium

Cyclone Amphan (2020) primarily affected:

  • AWest Bengal and Odisha
  • BTamil Nadu
  • CGujarat
  • DKerala
View solution
Correct Option: A
Amphan, May 2020 — West Bengal and parts of Odisha + Bangladesh.
Q 10 Latur Hard

The Latur earthquake of 1993, devastating despite moderate magnitude (~6.2), occurred in:

  • AMaharashtra
  • BKarnataka
  • CAndhra Pradesh
  • DMadhya Pradesh
View solution
Correct Option: A
Latur, Maharashtra, 30 Sept 1993; ~10,000 deaths. Intra-plate quake.
Q 11 Sendai Hard

The Sendai Framework for Disaster Risk Reduction covers the period:

  • A2000-2015
  • B2005-2015
  • C2015-2030
  • D2020-2050
View solution
Correct Option: C
Sendai Framework 2015-2030; 4 priorities + 7 global targets.
Q 12 Volcano Hard

India's only active volcano is located at:

  • ABarren Island, Andamans
  • BLakshadweep
  • CSundarbans
  • DKerala coast
View solution
Correct Option: A
Barren Island, Andaman. Narcondam is dormant.
Q 13 Drought Medium

A drought defined by soil-moisture deficit affecting crops is called:

  • AMeteorological drought
  • BHydrological drought
  • CAgricultural drought
  • DSocio-economic drought
View solution
Correct Option: C
Agricultural drought = soil-moisture deficit. Meteorological = rainfall < 75% of normal; Hydrological = surface/groundwater deficit.
Q 14 Floods 2018 Hard

The 2018 floods, called the worst in a century, hit:

  • AKerala
  • BUttarakhand
  • CBihar
  • DMumbai
View solution
Correct Option: A
Kerala floods 2018; ~480 deaths.
Q 15 CDRI Hard

The Coalition for Disaster Resilient Infrastructure (CDRI), HQ New Delhi, was launched in:

  • A2005
  • B2015
  • C2019
  • D2023
View solution
Correct Option: C
CDRI 2019, launched by India at UN Climate Action Summit.
Q 16 DM Cycle Medium

The disaster management cycle consists of how many phases?

  • A2
  • B3
  • C4
  • D6
View solution
Correct Option: C
4 phases: Mitigation → Preparedness → Response → Recovery.
Q 17 Joshimath Hard

The Joshimath subsidence (2023) is located in:

  • AUttarakhand
  • BHimachal Pradesh
  • CJammu & Kashmir
  • DSikkim
View solution
Correct Option: A
Joshimath, Uttarakhand; land subsidence cracking houses.
Q 18 DM Act Medium

The Disaster Management Act, India's foundational DM law, was passed in:

  • A1995
  • B2001
  • C2005
  • D2010
View solution
Correct Option: C
DM Act 2005, after the Indian Ocean Tsunami.
Q 19 UNDRR Hard

UNDRR — the UN body for Disaster Risk Reduction — was previously called:

  • AUNISDR
  • BUNHCR
  • CUNDP
  • DUNEP
View solution
Correct Option: A
UNISDR → UNDRR (renamed 2019).
Q 20 Match Hard

Match each cyclone with its year:

(i) Amphan (a) 2023
(ii) Biparjoy (b) 2020
(iii) Fani (c) 2021
(iv) Tauktae (d) 2019
  • A(i)-b, (ii)-a, (iii)-d, (iv)-c
  • B(i)-a, (ii)-b, (iii)-c, (iv)-d
  • C(i)-c, (ii)-d, (iii)-a, (iv)-b
  • D(i)-d, (ii)-c, (iii)-b, (iv)-a
View solution
Correct Option: A
Amphan → 2020; Biparjoy → 2023; Fani → 2019; Tauktae → 2021.

43.17 Quick Recall

ImportantQuick recall
  • Hazard = threat. Disaster = consequence with population loss.
  • Risk = Hazard × Vulnerability × Exposure ÷ Capacity.
  • 5 hazard types (UNDRR): Geological · Hydrological · Meteorological · Climatological · Biological. (+ Technological.)
  • Earthquake vocab: Focus/Hypocentre · Epicentre · P/S/Surface waves · Magnitude (Richter, Mw — energy) vs Intensity (Mercalli I-XII — damage).
  • India seismic zones: II (low) · III (moderate) · IV (high) · V (very high — NE, A&N, Bhuj, parts of Uttarakhand, HP, J&K).
  • Major Indian quakes: Bihar-Nepal 1934 (8.0) · Assam 1950 (8.6) · Uttarkashi 1991 · Latur 1993 (intra-plate) · Chamoli 1999 · Bhuj 26 Jan 2001 (Mw 7.7, 20k deaths) · Indian Ocean Tsunami 26 Dec 2004 (Sumatra Mw 9.1, 230k deaths) · Kashmir 2005 (80k) · Sikkim 2011 · Nepal-Gorkha 2015.
  • Volcano: Barren Island (Andaman) is India’s only active. Pacific Ring of Fire holds 75% globally.
  • Tsunami: Indian Ocean 2004 led to INCOIS Tsunami EWS, Hyderabad 2007.
  • Floods: Riverine · Flash · Urban · GLOF · Coastal. Cases: Kedarnath 2013 · Kerala 2018 (worst in century, ~480 deaths) · Mumbai 2005 · Chennai 2015 · Bengaluru 2022 · Sikkim GLOF 2023.
  • Cyclones (named by WMO/ESCAP Panel): Bay of Bengal more active than Arabian Sea. Saffir-Simpson 1-5 (Atlantic); IMD scale (North Indian Ocean). Cases: Odisha 1999 · Phailin 2013 · Hudhud 2014 · Vardah 2016 · Fani 2019 · Amphan 2020 · Tauktae 2021 · Yaas 2021 · Biparjoy 2023 · Remal 2024.
  • Drought types: Meteorological (rainfall) · Hydrological (water) · Agricultural (soil moisture) · Socio-economic. Prone: Bundelkhand, Vidarbha, Marathwada, Telangana, Rayalaseema, Saurashtra, Kutch.
  • Landslides: Western Ghats, Himalayas. Malin 2014, Wayanad 2024, Joshimath subsidence 2023.
  • Heatwaves: ≥ 40°C plains (IMD). 2010 Ahmedabad → first South Asian HAP. 2015 Andhra/Telangana 2,500+ deaths.
  • Indian DM framework: DM Act 2005 · NDMA 2005 (PM chairs, Delhi) · NDRF 2006 (16 battalions, HQ Ghaziabad) · NIDM · SDMA/DDMA · IMD (1875) · INCOIS (1999) · CWC (1945) · GSI (1851) · NRSC/ISRO Bhuvan · CDRI 2019 (Delhi) · Aapda Mitra · Sachet app.
  • DM cycle: Mitigation → Preparedness → Response → Recovery.
  • Mitigation: Structural (codes IS 1893, IS 4326; cyclone shelters; seawalls) + Non-structural (zoning, EWS, insurance, education).
  • International: Yokohama 1994 → HFA 2005-2015 → Sendai 2015-2030 (4 priorities + 7 targets) → UNDRR (formerly UNISDR).