Spain and the latent risk of tsunamis: vulnerable cities and prevention actions

Spain, despite not being considered a high-risk area for tsunamis, is not exempt from the possibility of experiencing this devastating natural phenomenon. A recent study titled 'Probabilistic Tsunami in the Mediterranean Sea' has raised concerns about the Spanish cities most prone to being affected by a tsunami, highlighting the Alboran Sea as one of the areas with higher seismic activity in the country and, therefore, with a greater risk of suffering tsunamis that could extend from Valencia to Malaga, including the Balearic Islands. The Averroes marine fault, located near the island of Alboran, has been identified as capable of generating waves up to six meters high, which could reach the coast in an extremely short period of time, between 21 and 35 minutes. This rapid arrival of a tsunami to the coast poses an additional challenge for authorities and the population in terms of response time and evacuation. In this sense, it is pointed out that a tsunami originating at Cape St. Vincent, located south of Portugal, would take approximately 40 minutes to impact the city of Cadiz, while those generated in southern Italy or the Azores would require more time to reach the Spanish coasts. The Mare Nostrum region, which covers the Atlantic coast where cities like Cadiz and Huelva are located, is also identified as a potential tsunami risk zone. The coastal cities of the Gulf of Cadiz and the Alboran Sea are considered the most vulnerable to the threat of tsunamis, highlighting the importance of conducting geological studies and simulations to map these risk areas and establish effective emergency plans. According to Emilio Carreño, director of the National Seismic Network, the region spanning from Torrevieja to the Strait of Gibraltar has the highest seismic activity in Spain, making it one of the areas at greatest risk of experiencing tsunamis. The Intergovernmental Oceanographic Commission has already warned about the likelihood of a tsunami with a height exceeding one meter hitting the Mediterranean coast in the next 30 years, with 100% certainty. In the specific case of the Cadiz coast, the probability of a tsunami of this magnitude is lower, estimated at 10% in the next 50 years. Although Spain has experienced tsunamis throughout its history, these events have been less frequent and of lower magnitude compared to other regions of the world. An event that marked Spain's history in relation to tsunamis was the 1755 earthquake with its epicenter off the coast of Lisbon, which generated a tsunami that severely affected cities like Cadiz and Huelva. Studies indicate that over 2,000 people lost their lives in Spain due to the 15-meter waves generated by this Portuguese earthquake. To this day, marine deposits can still be found several kilometers off the coast of Cadiz, evidencing the devastating consequences of that historic tsunami. Although at the time of the 1755 earthquake there was not such an advanced earthquake measurement system as today, records indicate that the earthquake could have reached a magnitude of up to 8.5 on the Richter scale. In response to the growing awareness of the tsunami risk, the Spanish government approved the State Plan for Civil Protection against the Risk of Tsunamis in May 2021, with the aim of ensuring the safety of the population against this natural threat. Within this plan, different alert levels are established according to the event's magnitude, with red indicating a wave higher than 0.5 meters, yellow signaling a wave between 0.2 and 0.5 meters, and green representing no risk with waves smaller than 0.2 meters. This alert system aims to inform and guide the population in case of a tsunami, facilitating decision-making and authorities' coordination in emergency situations. In conclusion, although Spain is not considered a high-risk region for tsunamis compared to other parts of the world, the threat of this natural phenomenon should not be underestimated. It is essential to continue conducting research and studies to identify the most vulnerable areas, strengthen early warning systems, and promote public awareness on how to act in the face of a possible tsunami. History reminds us that nature can be unpredictable, so preparedness and prevention are key to minimizing the impacts of these catastrophic events.