On Edge: The Great Nicobar project faces a great engineering question

Standing as a natural sentinel at the western gateway of the Strait of Malacca, Great Nicobar Island anchors India's proposed mega-project, comprising a greenfield international airport, a township and its centrepiece, an International Container Transshipment Terminal at Galathea Bay.

The project seeks to strengthen the country’s position in global maritime trade by leveraging the island's proximity to the East–West shipping route and reducing dependence on foreign transshipment ports.

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Rising just 40 nautical miles from the world's busiest maritime corridor, the deep-water haven at Galathea Bay boasts natural draft depths, capable of accommodating the globe's largest ultra-large container ships. Driven by a phased 16,610-hectare master plan through 2047, the mega-development couples a 14.2 million TEU container terminal with a high-capacity international airport designed to welcome 10 million annual travellers.

In June this year, the Central government announced that heavy machinery will likely roll onto the shores of Great Nicobar Island to begin ground construction of the Rs 91,000-crore mega-infrastructure project by 2028.

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Yet, beneath the high-stakes blueprint lies a formidable constraint: Great Nicobar falls within Seismic Zone V, the country's highest seismic risk category. 


As the 2028 construction deadline approaches, the central challenge facing India is not whether it should pursue this strategic project, but how to re-engineer rigid, sea-level-dependent maritime infrastructure for the island's unpredictable geology.

The seismic question

A 2019 study by the Indian Institute of Technology (IIT) Kanpur examined the region's seismic history. The researchers analysed deep sediment records from Badabalu Beach in South Andaman, unearthing geological evidence of at least seven major tsunami events over the past 8,000 years.

By modelling these disasters, the IIT Kanpur scientists estimated that mega-earthquakes registering at a magnitude of 9.0 or higher recur roughly every 420 to 750 years.

More concerning for the port’s operational lifespan, however, was the recurrence interval for large-magnitude earthquakes of 7.5 or higher, which strike on a tighter loop of 80 to 120 years.

The report warned that the Andaman segment has accumulated enough tectonic strain to trigger a major subduction zone earthquake in the near future.

The researchers also pointed out a 2,000-year gap in the region’s sediment history, meaning data from this period continues to be missing.

However, the Environment Impact Assessment report—commissioned by the Andaman and Nicobar Islands Integrated Development Corporation Ltd. and executed by Vimta Labs, a major Indian contract research organisation providing environmental assessment for large-scale infra projects—argued that because the devastating 2004 Indian Ocean earthquake occurred so recently, the immediate probability of another mega-earthquake is low.

Attempts to contact the National Centre for Seismology did not yield a response by the time of publication.

Dr CP Rajendran, a geologist who has spent decades studying subduction zones, has called out this interpretation as a somewhat misreading of tectonic behaviour. Earthquake recurrence is non-linear, meaning centuries of absolute quiet can be disturbed by sudden, consecutive quakes.

Dr. Rajendran also cautions against focusing solely on a repeat of the 2004 event. "The source of the 2004 earthquake was actually quite far from Great Nicobar, starting near Banda Aceh before it ruptured 1,200 kilometres all the way to the tip of North Andaman," he notes. "But the Nicobar structure area itself is highly prone to independent, localised earthquakes of magnitude 7.7 to 8.5."

"The assumption of a clean 500-year periodicity is fundamentally wrong because we simply do not find that kind of linear regularity in the geological record," he said. "If you look back in history over the last 6,000 years, examining the actual occurrence of great earthquakes, you find that there are periods of intense clustering and then there is a large gap."

The concern is compounded by co-seismic subsidence—the permanent sinking of land during an earthquake. During the 2004 magnitude 9.1-9.3 earthquake, portions of Great Nicobar permanently sank by three to six feet into the ocean.

The island's coastal topography also consists of loose, saturated tertiary sandstone and shale layered over rigid volcanic rock. When subjected to intense seismic shaking, this specific geological mix undergoes liquefaction — a process where solid ground loses its strength and behaves like a liquid — causing heavy, rigid real estate to tilt, fracture, or slide into the sea.

“When we talk about these issues, there are two things to consider. One is that when the land goes down, there could be a tsunami. Along with that, there is also the issue of sea-level change. The sea will aggressively move further onto the land. So, what you see now may not remain the same. The situation could be very different 50 or 70 years from now because sea levels are also rising due to climate change. These are the issues we need to consider,”Dr Rajendran said.

Furthermore, the project requires clearing coastal mangroves. "Mangroves act as a physical, geological wall against tsunamis," he warns.

The engineering blueprint

Rather than treating the island's restless geology as a deal-breaker, modern engineering approaches it as a complex design puzzle—a formidable challenge, but one solvable through an unconventional design philosophy.

"Dynamic coastlines that undergo violent, cyclic uplift and sink driven by mega-thrust earthquakes and subduction zone tectonics pose severe environmental and structural challenges," states Dr. Dipti Ranjan Sahoo, Professor and Dean of Infrastructure at the Department of Civil and Environmental Engineering, IIT Delhi.

"However, there are engineering solutions available to establish and develop maritime infrastructure in these coastlines to overcome such challenges by adopting innovative design and techniques in structures and foundations."

To tackle the twin challenges of the coastline permanently sinking and the ground turning into unstable quicksand during a quake, Dr Sahoo outlines a range of engineering measures.

The first step focuses entirely on fixing the ground itself.

The soil around the Galathea river basin is naturally weak and water-logged. Before building anything on top, heavy machinery packs the soil down tightly, squeezing out loose air and water pockets. Massive stone columns and vertical drains sink deep into the earth. If an earthquake strikes, these drains act like escape valves, letting trapped water rush out safely so the ground doesn't turn into a muddy liquid.

For heavily loaded industrial areas, a specialised concrete grout injects right into the soil grains, essentially gluing the loose earth together into a solid, artificial rock mass. Where the surface ground is too stubborn to fix, the layout bypasses it entirely by driving massive steel and concrete pillars deep into the earth, anchoring the port directly onto the solid volcanic bedrock hidden far below the surface.

The second step — instead of building rigid, heavy concrete docks that can crack or snap if the coastline drops, the design utilises highly adaptive, flexible structures. This involves using floating docks and jetties made of ultra-tough, buoyant materials that ride the waves and rise or fall naturally with the water level. Whether the tide changes or the island itself sinks a few feet, these docks just float along with the shift.

To support heavy machinery on land, the port would use flexible foundations that safely bend and absorb seismic movement instead of cracking under pressure.

The blueprint also introduces a modular foundation system—a mix of rigid blocks and flexible plates tied together by high-strength cables. During an earthquake, this acts like a shock absorber, dynamically changing how the building vibrates so it doesn't rhythmically shake itself to pieces.

Finally, out in the open water, massive wave deflectors, reinforced artificial hills, and adjustable seawalls stand ready to take the first, brutal hit of a tsunami—shattering the wave's power before it ever touches the main port.

Redefining infrastructure

While proponents of the project point to technologically advanced nations like Japan and Taiwan as evidence that mega-infrastructure can thrive on active plate boundaries, Dr Rajendran notes a crucial difference in logistics.

"Japan is a fully connected mainland system," he said. "If an earthquake strikes Tokyo, they have the automated systems, the secondary power grids, and the immediate domestic supply lines to manage the crisis,” he added.

“Great Nicobar is an extremely isolated island hundreds of kilometres from the Indian mainland. Maintaining and protecting high-tech, rigid structures in such total isolation is a completely different challenge, and even the most advanced mainland systems, like Fukushima, have shown how catastrophic unexpected failures can be."

The countdown to 2028 is not merely a timeline for clearing land and pouring concrete; it is about finding how alternative engineering approaches can be adapted to the island's geological realities.

The project's long-term resilience may ultimately depend on how effectively its engineering solutions perform in an inherently volatile geological environment.