There is a nearly 100 percent probability that a tsunami exceeding one meter in height will strike the Mediterranean region within the next 30 years, according to warnings issued by UNESCO. Major coastal cities including Marseille, Alexandria, and Istanbul face significant exposure as rising sea levels amplify the threat to vulnerable shorelines.
Understanding Mediterranean Tsunami Risks
While oceanographic attention frequently centers on the Pacific and Indian oceans—where the vast majority of seismic sea waves occur—coastal communities along the Mediterranean Sea face an underappreciated danger. According to Bernardo Aliaga, lead tsunami expert at UNESCO, the risk in the Mediterranean is often underestimated because large events happen infrequently and the hazard fails to pass effectively from one generation to the next. In the Mediterranean, Aliaga states, it is not a question of if a tsunami will strike, but when.
Historical precedent underscores the danger. One of the deadliest earthquakes in recorded history struck Portugal on All Saints’ Day in 1755, triggering a devastating tsunami that reached heights of six meters in Lisbon and Cádiz. Up to 50,000 people died during the initial earthquake, while many others perished in the subsequent fires and flooding.
Enhancing Regional Preparedness and Warning Centers
In response to these persistent threats, UNESCO is expanding its “tsunami-ready” program to ensure vulnerable coastal areas know how to respond effectively. Five new Mediterranean communities are scheduled to join 40 existing tsunami-ready towns and cities across 21 countries. The expansion includes Marseille in France, Alexandria in Egypt, Istanbul in Turkey, Cannes in France, and Chipiona, a Spanish Atlantic town near Cádiz.
This initiative forms part of UNESCO’s broader effort to ensure all at-risk coastal communities worldwide have actionable response plans by 2030. Progress has already been made in upstream detection. According to UNESCO, the Pacific Tsunami Warning Centre—hosted by the United States—has responded to 125 tsunami events since the devastating 2004 Indian Ocean disaster, averaging seven events per year.
Regional warning infrastructure has similarly expanded. Five dedicated tsunami-warning centers now cover the Mediterranean and northeast Atlantic, operated by Greece, Turkey, Italy, France, and Portugal. While these technical upstream systems are well-established, UNESCO emphasizes that closing local preparedness gaps remains critical to ensuring that visitors and residents understand emergency warnings when disaster strikes.
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