Before the earthquake, Port Royal held roughly 6,500 people in about 2,000 buildings — many of them multi-storey brick structures, all built on loose, water-saturated sand at the tip of the Palisadoes peninsula. When the shaking began at approximately 11:43 AM, that sand behaved exactly as unstable wet sand does under violent vibration: it liquefied, briefly taking on the properties of a fluid.
Eyewitness accounts describe the ground itself appearing to move in waves, fissures opening and closing — crushing people caught inside them — and entire streets of brick buildings sliding or sinking vertically into the earth, occupants and all. A tsunami followed within moments, lifting moored ships bodily over the rooftops of buildings still standing and depositing them among the ruins; one frigate, HMS Swann, was carried inland over the wreckage. By the time the ground resolidified, roughly two-thirds of the city and an estimated 2,000 people had gone under; a further 3,000 died of injuries and disease in the days that followed.