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........

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