Context:

The Environmental Impact Assessment (EIA) report for the Great Nicobar Infrastructure Project (GNIP) has drawn criticism for underestimating the earthquake and tsunami risks in the region—despite the area’s high seismic vulnerability, as seen during the 2004 Indian Ocean tsunami.

About the Great Nicobar Infrastructure Project (GNIP):

• Aims to develop:
  • Trans-shipment port
  • International airport
  • Township
  • 450 MVA gas and solar-based power plant
• Located on Great Nicobar Island (GNI) in the Andaman and Nicobar group.
• Received environmental and preliminary forest clearances from the central government.

Concerns Raised:

• Environmental Impact:
  • Massive deforestation and biodiversity loss
  • Threats to indigenous tribes
• Seismic Risk:
  • Zone V – the highest seismological risk category in India.
  • Lies near the Andaman Subduction Zone, where the Indian Plate dives beneath the Burmese Microplate—a highly active seismic belt.
  • The 2004 earthquake (magnitude 9.1–9.3) and resulting tsunami devastated Nicobar Islands, underlining future risks.

Earthquake: A Brief Overview

• Definition:
  Sudden shaking of the Earth’s surface caused by movement along faults in the Earth’s crust due to tectonic forces.
• Earth's Structure:
  • Crust (solid)
  • Mantle (viscous)
  • Outer Core (liquid)
  • Inner Core (solid)
• Lithosphere = Crust + Upper Mantle → composed of tectonic plates.

Causes of Earthquakes:

• Tectonic plates are constantly in motion.
• When stress exceeds the strength of rocks, it leads to fractures (faults).
• Sudden release of built-up stress = earthquake.
• Epicenter: Point on Earth's surface directly above the origin (focus) of the earthquake.
• Most intense shaking occurs near the epicenter.

Measuring Earthquakes:

• Seismometers: Instruments used to detect and measure seismic waves.
• Richter Scale: Measures magnitude (energy released), scale from 0–10.
• Mercalli Scale: Measures intensity based on observed damage.

Seismic Waves:

India’s Earthquake Vulnerability:

• 58.6% of India’s landmass is prone to moderate to severe earthquakes.
• Seismic Zonation:

Why Accurate Seismic Assessment Matters for GNIP:

• Great Nicobar Island lies in Zone V, near a major subduction zone, making it extremely earthquake-prone.
• Any large infrastructure in such areas must:
  • Consider historical seismicity (like 2004).
  • Include tsunami risk assessment.
  • Ensure disaster-resilient design and early warning systems.

Conclusion:

The GNIP's seismic risk assessment must be revisited with scientific rigour, given the island's vulnerability. Ignoring lessons from 2004 could result in catastrophic environmental and human consequences. Long-term sustainability demands a precautionary approach combining development with disaster preparedness.