THE powerful earthquake off eastern Russia last month, did more than shake buildings. It jolted the global imagination.

Pakistan may have felt no tremors, but the tectonic threat lurking beneath our own seas is a real and urgent concern. For Karachi, the danger lies just offshore in the Makran Subduction Zone (MSZ), a tectonically complex boundary stretching along the coasts of Iran and Pakistan, where the Arabian Plate dives beneath the Eurasian Plate. Near Gwadar, a triple junction with the Indian Plate adds another layer of seismic risk.

In 1945, the eastern MSZ segment ruptured, unleashing a magnitude 8.1 quake and a devastating tsunami that battered Balochistan, Sindh and western India.

Geological records suggest this was a partial rupture. A full failure of the 900-kilometre zone could trigger an earthquake as strong as 8.7 to 9.2, matching history`s most powerful seismic events. Such a megaquake could send tsunami waves surging across Pakistan, Iran, Oman, India and East Africa.

For Karachi, a sprawling coastal metropolis of over 20 million, the implications are dire. A 2024 study by Hasan et al. simulated rupture scenarios across MSZ. In the worst case, tsunami waves up to 4.2 metres would slam into Karachi Port within 90 minutes.

Even smaller ruptures could send waves up to 2m to 3m crashing ashore, still capable of severe damage. Port Qasim remains vulnerable, especially during high tide or strong winds. In a city as densely populated and poorly planned as Karachi, the fallout could be catastrophic.

Critical coastal infrastructure compounds the risk. Karachi Port, which is essential to our economy, would be among the first to suffer. Tsunami currents could displace vessels, destroy piers and flood inland terminals. Nearby, the Karachi Nuclear Power Plant (Kanupp) sits at sea level, lacking sufficient protections. Damage here could have consequences far beyond Karachi.

Inland, the outlook remains bleak. Highrises built on reclaimed land in Clifton and DHA face flooding and foundation risks like scouring and liquefaction. Karachi`s expansion into the sea has created expensive but fragile real estate. Areas like Korangi Industrial Zone and Gizri Creek low-lying and poorly drained could trap floodwaters and suffer contamination from sewage and industrial waste.

Time is the most unforgiving factor.

Karachi would have just 90 minutes between quake and tsunamitoo short for mass evacuation, too long to stay idle.

Urgent action is needed.

This begins with emergency preparedness. Karachi must develop an integratedearly warning system offshore seismic sensors linked to real-time networks, mobile alerts, sirens and emergency broadcasting. These must be regularly tested, not left dormant. Public education is critical; most citizens lack basic tsunami awareness.

Drills in schools, offices and hospitals could tr ansform panic into prepare dness.

Infrastructure must evolve. Kanupp and coastal installations need rigorous risk assessments and upgrades including sea walls, elevated control rooms, and floodresistant systems. Karachi Port`s logistics networks should be retrofitted to withstand wave forces. New coastal construction must follow tsunami-resilient codes; older shoreline structures must be re-evaluated and revamped.

The city must also restore what urbanisation has erased. Natural buffers like mangroves, lagoons, and creeks, which absorb wave energy, have been degraded. Gizri Creek, once a vital drainage basin, is now blocked and polluted. Reviving such ecosystems could reduce the flood impact andaid recovery.

Governance must anchor the effort.

Strong zoning laws should prevent new development in high-risk zones. Industrial units storing hazardous materials must relocate sensitive functions inland. Municipal authorities must collaborate with NDMA,Suparco, and global agencies to map evacuation corridors, model risk scenarios and conduct full-scale drills. This isn`t a single initiative; it must be embedded in longterm urban planning and policy.

Global lessons abound. Japan, Chile, and Indonesia have forged resilient coastlines through awareness, rapid response, and layered defence. In Japan, children are taught from birth what to do when the ground shakes. In Indonesia, the memory of 2004 reshaped everything from building codes to national emergency protocols.

Karachi must follow suit.

The Russian quake wasn`t our tragedy, but it is our warning. The MSZ isn`t dormant, it`s waiting. The Arabian Sea won`t offer a second chance. We already possess the models, the warnings, and examples from across the world. What remains is to act. And act now before the sea comes calling, and history asks if we were ready. • The wnter is an environmentalist, climate joumalist, and founder of Clifton Urban Forest, Karachi.