A new study published in Geophysical Research Letters reexamines the magnitude 7.2 earthquake that struck near the Greek island of Amorgos on July 9, 1956, and the devastating tsunami that followed. By integrating historical seismological data, geological records, and modern hydrodynamic simulations, researchers shed new light on the mechanisms that produced the deadliest tsunami in modern Greek history.
The 1956 Amorgos earthquake remains the largest instrumentally recorded seismic event of the 20th century in Greece. It caused widespread destruction across the Cyclades islands. Contemporary reports documented more than 50 deaths and several hundred injuries, with many victims caught in building collapses or swept away by waves. Entire coastal districts, including parts of Amorgos, Astypalaia, and Santorini, suffered severe damage.
One of the most striking features of the disaster was the tsunami. Wave run-ups exceeded 20 meters in certain locations, an unusually high value for an earthquake of this size. Harbors, boats, and shoreline settlements were devastated. Yet until now, the precise causes of the extreme tsunami heights had remained debated.
The new study used reprocessed seismic records from 1956 alongside fault-rupture modeling to estimate the extent of seafloor displacement. The results confirm that a normal fault rupture near Amorgos was the primary driver of the tsunami. However, the team also modeled alternative scenarios and found that the earthquake likely destabilized nearby submarine slopes. These triggered underwater landslides, which in turn amplified wave energy in specific basins.
This dual source - fault rupture plus landslides - helps explain why some islands experienced much higher run-up than others at comparable distances from the epicenter. For example, villages on Amorgos and Astypalaia were struck by far greater waves than expected from a fault-only model.
The authors note that these findings have broader implications for assessing future tsunami risk in the eastern Mediterranean. The Aegean Sea, with its steep submarine topography and active fault zones, is particularly prone to combined earthquake–landslide tsunamis. “The interaction of faulting and landsliding in tsunami generation highlights the need to reassess coastal risk in the Cyclades and other tectonically active basins,” the study concludes.
Beyond hazard assessment, the research underscores the value of combining historical documentation with modern scientific tools. Eyewitness accounts and damage surveys from 1956 provided critical constraints for the models, while advances in numerical simulation allowed the team to replicate tsunami behavior with far greater accuracy than was possible at the time.
The study positions the 1956 Amorgos event as a benchmark case for the Mediterranean. By clarifying its causes, the authors argue, researchers can better prepare for future disasters in a region where densely populated coasts and tourist infrastructure remain vulnerable.
The findings also speak to longer-term questions of Aegean history. Ancient coastal settlements, from Cycladic towns to Minoan harbors on Crete, would have faced similar tsunami hazards in antiquity. Geological evidence from Santorini, Crete, and other islands suggests repeated tsunami events over millennia. By studying the 1956 disaster, scientists and archaeologists gain a clearer picture of how natural forces may have reshaped settlement patterns in the prehistoric and classical Aegean.
Nearly seven decades later, the lessons of Amorgos remain urgent. The disaster stands as a reminder that in the Aegean, seismic risk comes not only from the shaking of the earth but also from the waves it can unleash.
The preparation of this article relied on a news-analysis system.