This exploration looks at a long memory of Mediterranean tsunamis and the striking scenes they left behind. One story dates back to January 31, 1756, when the sea’s violence was so great that rocks were ripped from their beds and hurled offshore, disappearing to depths of eighty meters as if they were mere pebbles. Long after the waves receded, the ground bore evidence in the form of huge boulders stacked in the landscape. The population today often passes by without noticing or understanding why those rocks remain, yet they stand as undeniable proof of nature’s power in a handful of seconds.
Geologist and geographer Francesc Xavier Roig has spent years tracing tsunami records in the Western Mediterranean, bringing into focus a reality few people knew. His latest study, A Review of Tsunami Deposits in the Western Mediterranean, appears in a recent issue of the Journal of the Geological Society of Spain.
Among 1756’s events, accounts describe how fish were stranded inland and how large stones were displaced far from the shore, with historical records noting a wave that traveled more than two kilometers inland. Mallorca drew particular attention to the geographer’s findings.
The Balearic Islands suffered some of the clearest impacts from the 1756 tsunami, which followed an earthquake off the Algerian coast. This seismic activity arose from the collision of tectonic plates, and its effects were most visible on Menorca and Formentera, where massive blocks still lie along the southern shore. In these places, rocks average around 8.5 tons but can reach much heavier weights, sometimes about 32 tons.
Waves moving at 700 km/h toward Spain
Roig notes that the Algerian earthquake produced a tidal surge racing northward at astonishing speed. In roughly 35 to 40 minutes, the first waves struck Formentera and Ibiza, with earlier reaches to Mallorca, Menorca, and other points along the Levante coast. In Formentera, the wave rose to about 12 meters, crashing into Punta Prima’s cliffs and pushing blocks inland, some towering well above a person. These remnants remain visible today, forming a geological and historical record that remains largely unfamiliar to most people.
Tsunami debris has been located along other sections of the Spanish coastline as well, indicating similar processes in the Balearic region. The recurring pattern suggests that an Algerian earthquake under the sea can generate a tsunami that propagates in multiple directions, from Alborán to Menorca. This range of possible paths implies that the Spanish coast, especially its areas most exposed to Algeria, could experience future tidal events.
These rock beds, created by past tsunamis, have also been found at Castelló and Murcia. Large blocks lie near cliff edges close to the coast, slightly above sea level, and researchers attribute them to a tsunami that affected northern Algeria. In Castelló, what initially appeared to be rocks falling from a valley were identified as tsunami-derived debris after Roig confirmed their origins through consistent features.
Other centuries tell similar stories. In the Bay of Algeciras, blocks are linked to an earthquake near Almería in 1522, which impacted broad stretches of the western Mediterranean. Archaeological signs point to another tidal event in the Bay of Algeciras dating to the fourth century BCE, underscoring a long history of coastal disturbance. Fieldwork has documented remains at seven coastal sites, though many other locations have likely lost their traces to time and urban development. Even where blocks remain, many have been repurposed for construction over the centuries, notes Roig.
Spanish Levant, a tsunami risk zone
Is there today a real risk of another tsunami? Roig cautions that the possibility exists. He recalls a 2003 event with lower intensity that was clearly detectable along southern Ibiza. By comparing local papers with data from the 1756 event, the parallels held up under scrutiny.
Looking ahead, the Mediterranean sits in a high-risk zone because of northern Africa’s seismic activity. The region’s beaches, especially during peak season, invite heightened attention to potential hazards. While warning systems have advanced to limit impact by delivering timely alerts, their effectiveness varies. In the Pacific, warnings are generally more reliable because of vast distances and longer travel times; in the Mediterranean, a tsunami can arrive in minutes, complicating response measures.
A referenced article on the subject remains available for scholarly review: marked citation provided here for attribution (Journal of the Geological Society of Spain, 33(2)).
In sum, the Mediterranean region holds a persistent risk profile for tsunamis rooted in historical events and ongoing seismic activity. Preventive strategies hinge on improving surveillance and public awareness, given the rapid pace with which waves can reach shore and the historical lessons etched into the coastlines.
Notes on research and regional history are drawn from ongoing work in this field, with Roig and colleagues continuing to map and interpret tsunami deposits to better understand past events and anticipate future ones. The evidence collected across the Balearic Islands, Castelló, Murcia, and beyond provides a clearer picture of how sea-level disturbances have shaped the landscape over centuries.