Europe’s Tsunami Risk: A Hidden Threat to Coastal Cities

Imagine a tsunami striking Mediterranean cities like Cannes or Barcelona—cities that are far removed from the Pacific Ocean's notorious waves. It may seem unlikely, but the reality is that Europe’s coastlines are at risk. The Mediterranean and northeastern Atlantic are active tectonic zones, and though only 10% of the world’s tsunamis occur in these areas, history has shown that the risk is real. Since 1600 BCE, there have been over 290 recorded tsunamis in the Mediterranean, and despite the low frequency, these events have caused some devastating disasters in Europe’s past.

Take the infamous 1755 tsunami, triggered by an 8.5-magnitude earthquake southwest of Cape St. Vincent, Portugal. Just 40 minutes after the quake, a massive wave struck Lisbon, completely flooding its harbor and advancing up the Tagus River. This initial wave was followed by two more devastating surges, sending people scrambling to higher ground. Though tsunamis like this are more common in the Pacific, the Atlantic and Mediterranean have been hit by these massive waves far more rarely, with major events expected every 3 to 5 centuries. However, this doesn’t mean a disaster couldn’t happen tomorrow.

French and Spanish cities like Marseille and Chamonix are on the list of places most likely to be hit in the next 30 years, with a 100% chance of tsunami impact, though the waves may not be as catastrophic as those in the Pacific. While waves may be less than 3 feet high on average, it’s important to understand that tsunami danger is not just about height. Even waves just over a foot high can be deadly, as it’s the power of the water’s movement and the flooding that cause the most damage. A wave only 6 feet tall can lift cars, while smaller waves traveling up to 40 mph can create destructive water walls. For places with low-lying harbors, like Cannes, the impact could be even worse.

Aside from the extreme damage a tsunami can cause, there are smaller, but still costly, consequences. The shifting of sandbars on the ocean floor can disrupt underwater pipelines and deep-sea cables, affecting internet and communication infrastructure, which could cost millions in repairs. This is why UNESCO and other organizations are raising awareness and developing plans to minimize the risks of future tsunamis in Europe.

Europe isn’t alone in its tsunami concerns. The 2004 tsunami in Indonesia, caused by an earthquake off the coast of Sumatra, showed just how deadly these waves can be, with over 200,000 lives lost. Similarly, the 2011 Japan tsunami, triggered by an earthquake off the coast of Tōhoku, led to a devastating nuclear disaster and killed over 16,000 people. These events were wake-up calls, reminding us that tsunamis can be predicted and that early warnings save lives.

Today, thanks to advances in technology, we have an effective tsunami warning system in place. The key is speed: seismic waves travel 100 times faster than tsunamis, so scientists have enough time to analyze data and issue alerts within minutes of an earthquake. The warning systems provide vital information about when and where the tsunami will strike, and they also offer advice on evacuation. In coastal communities, the next step is training locals on how to act quickly. UNESCO’s Tsunami Ready program helps communities prepare by installing evacuation signs, creating safety procedures, and ensuring that tourists are informed of tsunami risks. Spain, for example, has distributed tsunami warning signs along its entire coastline, indicating evacuation routes.

One of the most at-risk areas is the Arousa fault under the Balearic Sea. A major earthquake here would leave coastal residents with just 21 minutes to evacuate before a tsunami hits. There are also 12 tsunami warning centers spread across Europe, which monitor ocean disturbances and help keep coastal residents informed.

While earthquakes remain the most common cause of tsunamis, other phenomena like volcanic eruptions, landslides, and even meteorite impacts can also trigger waves. With climate change, the Mediterranean could also experience more ‘meteotsunamis,’ triggered by extreme weather events, which, while smaller, can still cause significant damage. In 2006, a meteotsunami struck the harbor of Mahón in Menorca, Spain, causing tens of millions of euros in damage.

If you’re spending time in Europe’s coastal cities, it’s crucial to stay alert. If a tsunami warning is issued, remember: head to higher ground, avoid waiting for the perfect photo, and listen to local authorities. Tsunamis may seem rare, but knowing what to do can save your life.

Stay safe and prepared—your safety is in your hands!