THE CONTEXT: The magnitude-8.8 earthquake that struck off Russia’s Kamchatka Peninsula on 29 July 2025 at a shallow depth of 19 km generated four-metre local waves and triggered precautionary alerts across the Pacific, including Hawai, California, Japan and Chile.
India’s collective memory is still framed by the 26 December 2004 Mw 9.1 Sumatra–Andaman event, which killed >10,000 Indians and exposed gaps in coastal readiness.
GEOLOGICAL AND PHYSICAL PROCESSES:
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- Plate-tectonic setting: Tsunamis arise chiefly where oceanic plates thrust beneath continental or island arcs. Reverse (thrust) faults cause abrupt vertical displacement of the seafloor, pushing a water column upward and initiating a wave train. The Kamchatka event occurred along the Kuril–Kamchatka trench where the Pacific Plate subducts beneath the Okhotsk Plate at ~86 mm yr⁻¹.
- Wave propagation: A tsunami travels at jet-liner speeds (≈800 km h⁻¹ in deep ocean) with low amplitude and long wavelength, losing little energy until it shoals on continental shelves.
- Run-up and inundation: Wave height can multiply 5-10 times in the last kilometre of approach; harbour resonance and submarine landslides add local amplification.
GLOBAL HOT-SPOTS AND INDIA’S EXPOSURE:
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- Pacific “Ring of Fire” (80 % of historic tsunamis), Makran Subduction Zone (Pakistan–Iran), Sunda–Andaman arc, and Mediterranean Hellenic arc are prime generators. Probabilistic modelling suggests Makran can host Mw 9.2 events with >10 m waves at Pasni and Gwadar.
- Indian demographic stakes: About one-quarter of Indians (>40 million people) reside within 50 km of the shoreline, and 17 % of the national population clusters in 593 coastal districts
EARLY-WARNING ARCHITECTURE:
| LAYER | REGIONAL NODE | INDIAN INTERFACE | KEY METRICS |
|---|---|---|---|
| Detection | UNESCO-IOC Inter-governmental Coordination Groups (ICG/IOTWMS, PTWC) | Real-time mirrored feeds at ITEWC-INCOIS (Hyderabad) | Seismic trigger within 3 minutes |
| Confirmation | Bottom Pressure Recorders (BPR), tide-gauge arrays | 4 tsunami buoys, 36 seismic stations, 36 tide gauges: redundancy via VSAT + INSAT links | Wave confirmation < 10 minutes |
| Decision support | Decision Support System (DSS) coupled to high-resolution bathymetry | Automatic scenario library of 120,000 pre-modelled events | Public bulletin every 15 minutes |
| Dissemination | Common Alerting Protocol (CAP) gateways | Coastal sirens, Doordarshan TV crawl, cell-broadcast, Railway SMS | Drill outreach to 3,500 villages |
POLICY AND INSTITUTIONAL FRAMEWORK IN INDIA:
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- Disaster Management Act 2005: Legal basis for national / state disaster management plans.
- NDMA Guidelines on Management of Tsunamis (2010, under revision 2023): prescribe hazard zoning, vertical evacuation structures, school curricula and annual drills.
- Coastal Regulation Zone (CRZ 2019) & draft amendments (2024): Mandate 500 m setback line, promote multi-hazard shelters and restrict critical infrastructure in Eco-Sensitive Areas.
- Sagarmala and Bharatmala programmes integrate disaster-resilient design for ports and coastal highways.
THE ISSUES:
| DIMENSION | KEY PAIN-POINTS |
|---|---|
| Scientific | Near-field warning window (< 10 min) still too short for Andaman–Nicobar arcs; sparse offshore geodetic data; limited modelling of submarine landslide tsunamis. |
| Infrastructure | Patchy coverage of all-weather sirens; only 78 % of cyclone shelters are tsunami-certified; signage absents on ~45 % of tourist beaches. |
| Behavioural | “Run uphill” culture weak; school drills uneven, fishermen rely on peer networks more than official bulletins. |
| Governance | Funding skewed towards post-disaster relief; coastal land-use decisions dispersed across MoES, MoEFCC, State CRZ authorities, district collectors. |
COMPARATIVE GLOBAL BEST PRACTICES:
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- Japan: Seawalls up to 12 m, vertical-evacuation parks, RFID-based child tracking during drills.
- Chile: Mandatory WEA-compliant cell-broadcast on every handset sold post-2024.
- Indonesia: GNSS-enabled buoys plus community relay radios ensure first warning inside five minutes (InaTEWS).
TECHNOLOGICAL FRONTIERS AND NATURE-BASED SOLUTIONS:
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- Smart submarine-cable observatories: India’s planned 275 km Andaman seabed cable will embed pressure, tilt and hydrophone sensors for continuous real-time feeds.
- AI-assisted now-casting: Neural networks cut scenario run-time from 6 min to 45 s in pilot tests at INCOIS HPC cluster.
- Blue-carbon shields: Hydrodynamic modelling shows a 100 m mangrove belt can cut peak tsunami pressure by 90%; IIT-Bombay 2025 simulations confirm significant attenuation along the Sundarbans.
THE WAY FORWARD:
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- Complete seabed sensor cable by 2028, integrating GNSS-linked BPRs for near-field detection under five minutes.
- Legislate a Coastal Resilience Cess on port cargo and beachfront realty to fund multi-hazard shelters and siren upkeep.
- Mandate bilingual CAP push alerts on all mobile networks, with text-to-speech conversion for feature phones and fisher VHF channels.
- Retrofit at least one public building per coastal panchayat as a vertical-evacuation refuge using FEMA design codes adapted to Indian standards.
- Expand the mangrove stewardship programme to 2,000 sq km by 2030, offering blue-carbon credits to coastal Gram Sabhas.
- Institutionalise annual mock drills on National Tsunami Awareness Day (5 November) with dashboard transparency of participation metrics.
- Embed Tsunami Ready certification in the Swachh Bharat coastal beach ranking, creating positive competitive pressure on municipal bodies.
- Launch an open-access bathymetry and inundation atlas to guide district-level land-use plans and insurance underwriting.
- Set up a unified Coastal Hazard Management Authority to harmonise MoES, MoEFCC and NDMA mandates and fast-track funding.
- Incentivise indigenous R&D on low-cost GNSS reflectometry buoys, reducing import dependence and enabling dense arrays.
THE CONCLUSION:
Harnessing cutting-edge seabed sensing, blue-carbon bioshields and community-centric governance can compress the fatal “warning-to-impact” gap into a resilient “prepare-to-prosper” window. India’s coastal future depends not merely on reading seismic signals, but on translating them into swift, inclusive and science-anchored action.
UPSC PAST YEAR QUESTION:
Q. On December 2004, tsumani brought havoc on 14 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. 2017
MAINS PRACTICE QUESTION:
Q. Discuss how recent advances in seabed instrumentation and nature-based coastal defences can synergise to enhance India’s tsunami resilience.
SOURCE:
https://indianexpress.com/article/explained/explained-sci-tech/earthquake-generate-tsunami-10159403/
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