🌊 An exceptional medieval tsunami in the Caribbean

New scientific work has just unveiled a geological episode as spectacular as it is forgotten: a tsunami of exceptional magnitude that struck the Caribbean in the late 14th century.

The study, recently published in Geophysical Research Letters, relies on a surprising natural clue: massive corals, ripped from the reef and thrown several hundred meters inland on the island of Anegada, in the British Virgin Islands, north of the Lesser Antilles arc. Silent witnesses that, six centuries later, tell a story that human records never documented.


Researchers from IPGP discovered these corals during a field mission on Anegada. They mapped them precisely to obtain information on their distribution, data essential for constraining tsunami models. They then sampled the surface of the corals to accurately date their death using Uranium/Thorium dating techniques in two laboratories (at CEREGE in France and at HISPEC in Taiwan)

These corals are the geological trace of a major tsunami that occurred in the Antilles before the arrival of Christopher Columbus and the first chronicles on natural disasters which begin in the mid-17th century in the Antilles. This tsunami was produced by an earthquake of magnitude greater than 8 in the region.

It was possible to date this tsunami with unprecedented precision, which will allow for targeted historical research in the archives of coastal towns along the Atlantic in the United States, Canada, Europe, Africa...). Indeed, given the scale of the phenomenon, the waves very certainly crossed the entire ocean basin to strike these cities a few hours after the earthquake.

Corals Displaced by a Colossal Force

On the island, researchers identified dozens of corals up to about 6.6 feet (2 m) in diameter, now resting in areas the sea never reaches, even during the most violent storms. Their mere presence in this location indicates they were transported by a phenomenon of extraordinary power.

In order to determine the age of these corals, scientists used a dating method based on uranium isotopes. Result: the corals all died between 1381 and 1391, before Christopher Columbus arrived in this region and the first historical chronicles.

A Major Earthquake as the Likely Origin

By cross-referencing geological data with wave propagation models, the authors suggest that an earthquake of magnitude greater than 8 along a fault in the subducting American plate or at the subduction interface in the Puerto Rico Trench would be the cause of the death of these corals.

This earthquake would have created tsunami waves powerful enough to rip living corals from the reefs surrounding the island. The corals would then have been transported far inland before the sea receded and abandoned them.


The island of Anegada is a British Virgin Island located east of Puerto Rico, facing the Puerto Rico Trench where the North American Plate subducts beneath the Caribbean Plate at a rate of about 0.8 inch/year (2 cm/year). It is a limestone platform surrounded by fringing reefs. The dead corals were identified and mapped on the north coast of the island. They were ripped alive from the fringing reefs and transported between 1381 and 1391 CE by a tsunami wave.

This wave was very likely initiated by the rupture of the subduction interface during a mega-earthquake. The corals were abandoned on the platform at several meters of elevation when the wave retreated. They died there and remained preserved intact for nearly 650 years before the team discovered them during a field mission. Their presence attests that major tsunamis can occur on the eastern border of the Caribbean where the islands of the Antilles are also located.

A Geological Memory

The clues left in the field testify to a rare, powerful episode, capable of durably modifying coastal landscapes. This large-scale medieval tsunami certainly crossed the Atlantic to strike the coasts of Canada, Europe, or Africa. Being able to date it with such precision will allow for an efficient search for this event in historical archives.

The study underscores how much geological records can reveal major events that occurred before the historical period or in areas where populations were small or dispersed.

The Long History of Coastal Hazards

Beyond the discovery itself, this work reminds us that regions exposed to subduction or active faults can experience, even at very long intervals, large-scale tsunamis. The diversity of methods used — isotopic dating, field observations, modeling — thus allows the reconstruction of the dynamics of ancient events and refines the understanding of coastal hazards.

This is the entire objective of the work carried out for several years in the Caribbean by IPGP: identification and characterization on land and at sea of active faults likely to rupture and cause a tsunami, understanding the functioning and seismic cycle of the subduction zone, and searching for geological and historical traces of past earthquakes and tsunamis from the coast to the deep ocean. The goal is to reconstruct the history of past catastrophic events to better prepare for a future earthquake.

This study is therefore a major advance on these subjects. This medieval tsunami, previously unknown, revealed by corals scattered and frozen in the landscape for several centuries, offers a rare window into the natural history of the Caribbean. A history where the sea sometimes advances much further than imagined.

(HISPEC), High-Precision Mass Spectrometry and Environment Change Laboratory, National Taiwan University.