The 1956 Amorgos earthquake triggered a tsunami whose origin remained unclear. However, a massive underwater fault has now been identified as the main cause, calling into question previous hypotheses. This discovery sheds light on the current risks in the Aegean Sea, where worrying seismic and volcanic activity is taking place near Santorini.
By Laurie Henry
Cover photo: The semi-submerged Ariane rover. © Ifremer / Olivier Dugornay
Tsunamis are often associated with major subduction earthquakes in the Pacific, but the semi-enclosed Mediterranean basin is not spared. On 9 July 1956, an earthquake with a magnitude of over 7 shook the Aegean Sea, causing a devastating tsunami. With waves reaching 20 metres on some Greek coasts, it was the largest tsunami recorded in the Mediterranean in the last two centuries.
However, its precise origin remained unknown for a long time. A team of researchers from the French National Centre for Scientific Research (CNRS), the University of the Côte d’Azur and the Paris Institute of Earth Physics recently conducted an in-depth underwater survey. It revealed that the rupture responsible for the tsunami occurred on the Amorgos fault, which could be enough, on its own, to explain the catastrophe, calling into question hypotheses established over decades.