Could Spain's Mediterranean Coast Face a Powerful Tsunami? New Research Says the Risk Is Real

18-Tonne Boulders Tell a Troubling Story

Researchers studying the coastline around Cape Cope, near Águilas in the Region of Murcia, have made a striking discovery: enormous boulders weighing nearly 18 tonnes have been found stacked in ridges several metres above the current sea level. Some exceed four metres above sea level.

Published in the Journal of Iberian Geology, the research concludes that normal storm waves could not have moved or stacked these boulders in the formations they occupy today. The only plausible explanation, the scientists say, is a tsunami-scale event — likely triggered by seismic activity in the western Mediterranean and occurring within the last few thousand years.

Put simply: a tsunami has hit this stretch of Spain's Mediterranean coast before. And researchers warn it could happen again.

A Coast With More Seismic Activity Than Many Realise

The Region of Murcia is one of the more seismically active parts of Spain. Recorded earthquake magnitudes of 6 to 7 have been documented in the area, and the western Mediterranean sits at the convergence of the Eurasian and African tectonic plates — a zone capable of generating significant undersea earthquakes.

Despite this, tsunamis are rare in modern records for the Spanish Mediterranean coast, which has led to the risk being somewhat overlooked. The Cape Cope findings are particularly significant precisely because they fill in that historical picture.

Similar boulder formations with tsunami-related characteristics have also been identified in the Balearic Islands, Valencia, and Andalucía — suggesting the phenomenon is not isolated to Murcia.

The 1755 Lisbon Earthquake: A Historical Warning

The most well-documented tsunami to affect Spain's coastline came in the wake of the 1755 Lisbon earthquake — one of the most powerful ever recorded in Europe. The resulting tsunami swept inland along Spain's southern coast, killing over 1,000 people and causing widespread destruction.

That event was nearly 270 years ago. Since then, Spain's coastal towns have grown enormously — and with that growth has come a significant reduction in natural protections.

Why Today's Coast Is More Vulnerable Than Before

The research carries a particularly urgent warning: the Mediterranean coast is now more exposed to tsunami damage than it was centuries ago. The reasons are a combination of human activity and climate change:

• Loss of natural buffers — sand dunes, wide beaches and wetlands that once absorbed wave energy have been built over or eroded away along much of the coast
• Urban development — hotels, apartments, restaurants and roads now sit on ground that was once undeveloped shoreline, placing far more people and infrastructure in potential flood paths
• Rising sea levels — as sea levels increase due to climate change, any future tsunami wave would travel further inland than historical events, reaching areas that were previously safe

The combination of these factors means that even a tsunami of the same magnitude as a historical event would cause significantly greater damage today.

What Emergency Planning Exists

Spain does include tsunami risk in national emergency planning. The National Geographic Institute (IGN) monitors seismic activity across Spain and the western Mediterranean, and Civil Protection services incorporate tsunami scenarios into their contingency frameworks.

Spain is also part of the UNESCO Tsunami Early Warning and Mitigation System for the North-Eastern Atlantic, Mediterranean and Connected Seas (NEAMTWS), which aims to provide advance warning in the event of a significant undersea earthquake.

However, the time between a Mediterranean earthquake and a wave reaching the Spanish coast can be as little as 15 to 30 minutes — meaning early warning systems and public awareness are critical.

What This Means for Residents and Visitors

The research is not intended to cause alarm, but to inform. The probability of a significant tsunami striking the Spanish Mediterranean coast in any given year remains low. However, "low probability" is not the same as "impossible" — and the scale of development along Spain's costas means the consequences of such an event would be severe.

For residents and visitors in coastal areas, the most useful step is basic awareness:

• Know whether your area is in a low-lying coastal zone
• In the event of a strong earthquake felt near the coast, move inland and to higher ground immediately — do not wait for an official warning
• A sudden, unusual withdrawal of the sea from the shore is a classical warning sign of an incoming tsunami wave
• Follow instructions from Civil Protection (Protección Civil) and local emergency services

The boulders at Cape Cope are a reminder carved in stone: the Mediterranean has sent waves this powerful before, and the geology has not changed.

This article is based on reporting from Murcia Today, published April 21, 2026. It is for general information purposes only.