Since 2022, the Intergovernmental Oceanographic Commission has warned that the probability of a tsunami exceeding one meter in height in the Mediterranean Sea within the next 30 years is close to 100%. However, the question on everyone's mind is whether a tsunami could actually occur in Spain . For a tsunami to happen, there needs to be a vast expanse of ocean large enough to generate a massive wave.
In this article we are going to tell you how there can be a tsunami in Spain and what has happened historically.
Tsunami in Spain
Over the past 2500 years, Mediterranean countries have experienced several catastrophic tsunamis. The most famous occurred in 365, 1303, and 1908. The first two were caused by Greek-bow earthquakes, and the third occurred in the Strait of Messina. More recently, the most destructive tsunamis in the Mediterranean region struck the Aegean Sea in 1956, with waves up to 25 meters high, and northern Algeria in 2003, with a tsunami up to 2 meters high hitting the Balearic Islands. To learn more about the origin of these phenomena, you can consult our article on how tsunamis are generated.
The record of historical data convinces us that, indeed, the risk of a tsunami that could affect the Mediterranean Sea is real.
In the Spanish Mediterranean region, the greatest potential for a tsunami is the Averroes Sea fault in the Alberrán Sea. The data comes from a recent study by the China Shipbuilding Industry Corporation, published in the journal Scientific Reports, which states that not only normal and reverse faults can generate tsunamis, but also in this case jump faults. The earthquake caused waves up to 6 meters high on the Averroes Marine Fault, which took between 21 and 35 minutes to reach the coast.
However, the Spanish coast most prone to tsunamis will be the Atlantic Ocean. According to data from Tsunamis, in the next 50 years there is a 10% chance that a tsunami 1 meter high will hit the coasts of Huelva or Cádiz , and a 3% chance of waves 3 meters high. The events of 1755, which we described at the beginning of this article, are likely to be repeated, which is why some towns in southern Spain already have risk prevention plans and tsunami response plans in place. To better understand the connection between earthquakes and tsunamis, it is recommended to read about earthquakes and tsunamis : the connection between two natural phenomena.
Some history
November 1, 1755, was a very difficult day for Lisbon. The epicenter was located at a distance from the Portuguese coast still unknown to scientists. The so-called Lisbon earthquake occurred in the Atlantic Ocean. Seismologists estimate its magnitude to be between 8,7 and 9, and its moment magnitude was 0. The devastation caused by the disaster is well known: it was characterized by its prolonged duration and high level of violence, and it is estimated that between 60.000 and 100.000 people died in the disaster.
Furthermore, the earthquake was not an isolated event but was followed by a fire and, as is sometimes the case when large earthquakes occur in the ocean, the tsunami was comparable in size to the magnitude of the earthquake that struck it. The capital of Portugal was almost reduced to ashes.
As for the tsunami, waves are believed to have reached 5 meters in height in Lisbon, and at least 15.000 people died from the tsunami among the fatalities recorded in the disaster. The hardest hit coast was the Portuguese.
However, its impact was also felt on the Atlantic coast of Spain and Morocco. In Andalusia, waves battered the entire Atlantic coast, from Ayamonte to Tarifa. In Huelva, the damage was widespread, with an estimated death toll of around 1.000 and 400 in some of the hardest-hit towns , such as Ayamonte and Lepe, respectively, in addition to the destruction of a large part of the fishing fleet. The entire coast of Cádiz, all its towns, was affected by the tsunami. In Cádiz, waves of up to 18 meters were recorded, destroying part of the city wall, as well as causing flooding and damage from El Puerto de Santa María to Tarifa.
The image of a series of waves crashing onto the shore almost suddenly is terrifying. Other recent examples, such as the 2004 tsunami triggered by an earthquake off the coast of Sumatra , which killed nearly a quarter of a million people, confirm this. Although events like the Lisbon tsunami have occurred more or less repeatedly throughout history, we tend to associate tsunamis with phenomena more common in other parts of the world, such as the Pacific Ocean, where large earthquakes are more frequent. These phenomena can be caused by natural events, as in the case of the eruption of the Hunga Tonga volcano , which was also felt in Spain and reminds us of our vulnerability to natural disasters in the ocean.
Tsunami risk areas in Spain
The researchers explain that a state-level document has been prepared identifying the areas most vulnerable to tsunamis—that is, all of Spain's coastlines, with the exception of Asturias and Cantabria, where the impact is less significant. “It is unlikely to occur in these areas because there are no fault lines. These are located in the Gulf of Cádiz, northern Algeria, North Africa, and other places. Therefore, studies must be conducted at the community and municipal levels. To do this, it is essential to have information on how tsunamis can affect our coastlines.”
Spain currently has a Citizen Protection Plan against tsunami risks, which the Government will develop and approve in May 2021. As explained in the text published in the Official State Gazette (BOE), this is a “tsunami warning system” designed to inform civil protection authorities and public emergency services of the urgency of this threat, as well as potentially affected citizens. Although it only establishes “basic guidelines for planning the protection of civilians against tsunami risks,” it is essential that potentially affected cities have action plans and remain informed about how a meteotsunami could impact them.
Bay of Cádiz as a high-risk area
The Bay of Cádiz is a high-risk area due to its proximity to the various seismic faults that separate the Eurasian and African tectonic plates . Furthermore, it is worth noting that Spain was already affected by the 1755 Lisbon earthquake, which originated deep underwater. The resulting tsunami devastated the coasts of Huelva and Cádiz, killing more than 2.000 people along much of the Andalusian coast. For all these reasons, they decided to contact the Chipiona City Council, where the project would begin.
Chipiona is a pilot case of the tsunami preparation plan, and all the steps that must be taken to prepare the municipality are being studied, both the administrative part and the population as well as the emergency services. This plan will serve as a guide to other municipalities on how to prepare.
