Geophysical Hazards and Industrial Disasters: Earthquakes, Tsunamis, Landslides and Chemical Accidents

Earthquakes

Cause: the Indian plate moves north at about 5 cm a year and collides with the Eurasian plate. This makes the Himalaya and the Northeast highly seismic.

Seismic zones (BIS IS 1893):

• Zone V (very high): the Northeast, J&K and Ladakh, Himachal, Uttarakhand, the Rann of Kutch, north Bihar and the Andaman & Nicobar Islands;
• Zone IV: Delhi, parts of the Indo-Gangetic plain;
• Zones III and II: lower risk.

About 59% of India's land is in Zones III–V. The revised seismic code (2025) introduced a new Zone VI for the most hazardous Himalayan belt. Verify the details before quoting.

Major quakes:

• Assam 1950 (M 8.6);
• Latur 1993 (M 6.2, about 10,000 deaths, in an area once thought stable);
• Uttarkashi 1991 and Chamoli 1999;
• Bhuj 2001 (M 7.7, about 20,000 deaths);
• Kashmir 2005;
• Sikkim 2011;
• Nepal 2015 (M 7.8, felt across north India).

Lessons:

• earthquakes don't kill, buildings do;
• most deaths come from collapsing non-engineered structures.

Mitigation:

• enforce the building codes (IS 1893, IS 13920 for ductile detailing);
• retrofit schools and hospitals;
• microzonation of cities;
• the National Earthquake Risk Mitigation Programme;
• seismic monitoring by the National Center for Seismology;
• public awareness and drills.

Tsunamis

Cause: undersea earthquakes (usually above M 7.5 with vertical displacement), submarine landslides or volcanoes.

The 2004 Indian Ocean tsunami followed an M 9.1 earthquake off Sumatra on 26 December 2004. It killed about 2.3 lakh people across 14 countries, including about 10,000 in India (Tamil Nadu and the Andaman & Nicobar Islands).

Response: the Indian Tsunami Early Warning Centre was set up at INCOIS, Hyderabad in 2007. It is a Regional Tsunami Service Provider for the Indian Ocean under UNESCO-IOC, and issues warnings within about 10 minutes. Mangroves and coastal shelterbelts reduced damage in places such as Pichavaram.

Tsunami Ready programme (UNESCO): Venkatraipur and Noliasahi in Odisha were India's first certified communities (2020).

Landslides

Extent: about 12.6% of India's land area is prone to landslides (GSI). This covers the Himalaya, the Western Ghats, the Nilgiris and the Northeast. The Landslide Atlas of India (ISRO, 2023) ranked Rudraprayag and Tehri among the most exposed districts.

Causes:

• natural: heavy rain, steep slopes, earthquakes and weak geology;
• human: road cutting, deforestation, quarrying, unplanned construction and hydropower tunnels.

Recent events:

• Joshimath land subsidence (2023);
• the Wayanad landslides (July 2024), about 230+ deaths at Mundakkai and Chooralmala after extreme rain;
• Malin, Maharashtra (2014);
• Kedarnath (2013), combined with floods.

Management:

• the National Landslide Risk Management Strategy (2019);
• landslide susceptibility mapping (GSI's national programme at 1:50,000);
• early warning pilots (GSI and Amrita University);
• slope stabilisation, drainage and bioengineering;
• carrying capacity studies for hill towns and regulation of construction;
• the Gadgil (2011) and Kasturirangan (2013) reports on the Western Ghats, and their eco-sensitive area debates.

Avalanches

Avalanches affect J&K, Ladakh (including Siachen), Himachal and Uttarakhand. Forecasting is done by DGRE, the Defence Geoinformatics Research Establishment of DRDO (formerly SASE).

Industrial and chemical disasters

Bhopal Gas Tragedy (2–3 December 1984): methyl isocyanate (MIC) leaked from the Union Carbide plant. It caused thousands of immediate deaths and lasting health effects. The government's figure is about 5,000+ deaths, and estimates go much higher.

Legal reforms that followed:

• the Environment (Protection) Act 1986;
• the Public Liability Insurance Act 1991, which makes insurance compulsory for hazardous industries;
• the Factories Act amendments of 1987;
• absolute liability (from M.C. Mehta v. Union of India, 1986, the oleum gas leak case), which is stricter than strict liability and allows no exceptions.

Other incidents:

• LG Polymers, Visakhapatnam (May 2020): a styrene gas leak;
• Vizag pharma explosions;
• Sigachi (Telangana, 2025);
• firecracker unit explosions.

Framework:

• the Manufacture, Storage and Import of Hazardous Chemical Rules 1989;
• the Chemical Accidents (Emergency Planning, Preparedness and Response) Rules 1996;
• NDMA guidelines on chemical disasters (2007);
• Major Accident Hazard (MAH) units must have on-site and off-site emergency plans;
• the National Green Tribunal awards compensation.

Nuclear and radiological safety: regulated by the AERB, with NDMA guidelines. The Civil Liability for Nuclear Damage Act 2010 addresses compensation.

Biological disasters and pandemics

COVID-19 was managed under the DM Act, which was invoked for the first time for a pandemic in March 2020. This was alongside the Epidemic Diseases Act 1897 (amended in 2020 to protect health workers). The pandemic showed the strengths of the DM Act (centralised command) and raised federalism concerns.

Analysis

Common threads:

• risk is constructed through poor building, unplanned growth and weak enforcement;
• early warning has worked for cyclones and tsunamis, but not yet for earthquakes or landslides;
• local capacity and regulation matter most.

The Sendai approach calls for risk-informed development. Every infrastructure project in a hazard zone should have a disaster impact assessment.

Common prelims traps

• India's tsunami warning centre is at INCOIS Hyderabad, not the IMD.
• Absolute liability came from M.C. Mehta (oleum gas), not the Bhopal case itself.
• Latur 1993 happened in a supposedly stable peninsular region.
• Zone V is the highest-risk zone in the long-standing code.

Quick self-test

1. *Why are Himalayan hydropower projects controversial after 2013 and 2023?* Slope instability, GLOFs and tunnelling in a seismic zone.
2. *What is the difference between on-site and off-site emergency plans?* On-site plans are prepared by the factory; off-site plans by the district for the surrounding area.
3. *What does microzonation do?* It maps ground shaking variation within a city to guide building rules.

Practice: Mains question

*"Earthquakes don't kill people; buildings do." In the light of this statement, evaluate India's earthquake preparedness. (250 words)*

Key terms

• Magnitude: the energy released, on the Richter or moment magnitude scale. Each whole step means about 32 times more energy.
• Intensity: the shaking felt at a place, on the Modified Mercalli scale. It varies with distance and soil.
• Liquefaction: saturated loose soil loses strength during shaking, as seen in Bhuj and in the Kathmandu valley.
• Subsidence: gradual sinking of land, as in Joshimath, caused by weak geology, drainage and construction load.
• Off-site emergency plan: a district-level plan to protect people outside a hazardous factory.

Analysis: the governance gap

India has strong laws on paper, but enforcement is weak:

• most private homes are built without engineers;
• municipal building permission rarely checks seismic detailing;
• hill states continue to expand roads and hydropower with limited geological review;
• inspection of hazardous factories is thin, and the Factories Act inspection regime has been relaxed in some states.

Remedies:

• third-party structural audits;
• incentives such as tax rebates for retrofitting;
• mandatory disaster impact assessments for hill infrastructure;
• stronger factory inspectorates;
• public disclosure of hazardous units near residential areas;
• training masons in earthquake-safe construction, a low-cost, high-impact step.

Practice: additional question

*Examine the causes of the increasing frequency of landslides in the Himalaya and the Western Ghats, and suggest a policy response. (150 words)*