As of 2022, the Intergovernmental Oceanographic Commission has warned that the probability of a tsunami over one meter high in the Mediterranean Sea in the next 30 years is close to 100%. However, what people wonder is whether there really can be a tsunami in Spain. For there to be a tsunami there must be a vast expanse of ocean sufficient to produce a large wave.
In this article we are going to tell you how there can be a tsunami in Spain and what has happened historically.
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Tsunami in Spain
During the last 2500 years, the Mediterranean countries have experienced several catastrophic tsunamis. The most famous occurred in 365, 1303, and 1908. The first two were caused by Greek arc earthquakes, and the third occurred in the Strait of Messina. More recently, the most destructive tsunamis in the Mediterranean region hit the Aegean Sea in 1956, with waves of up to 25 meters, and northern Algeria in 2003, with a tsunami of up to 2 meters that hit the Balearic Islands.
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 Tsumaps, in In the next 50 years there is a 10% chance that a 1 meter high tsunami will hit the coasts of Huelva or Cádiz, and 3% if we talk about waves of 3 meters. And it is the events of 1755 that we described at the beginning of this article that are likely to be repeated, which is why some towns in southern Spain already have risk prevention plans and action plans in the event of a tsunami.
November 1, 1755 was a very hard day for Lisbon. The epicenter was located at a distance from the coast of Portugal, still unknown to scientists, the so-called Lisbon earthquake occurred in the Atlantic Ocean, seismologists estimate that its magnitude may be between 8,7 and 9, and the magnitude of the earthquake is 0 moment magnitude. The devastation caused by the disaster is well known: it was characterized by its prolonged duration and high level of violence, and an estimated 60.000 to 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 influence was also felt on the Atlantic coast of Spain and Morocco. In Andalusia, the waves shook the entire Atlantic coast, from Ayamonte to Tarifa. In Huelva, the damage was widespread, with a estimated death toll of about 1.000 and 400 in some of the hardest-hit townss, 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 the towns were affected by the tsunami. In Cádiz, waves of up to 18 meters were recorded, destroying part of the city wall, in addition to causing flooding and damage from Puerto de Santa María to Tarifa.
The image of a series of waves hitting 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 almost a quarter of a million people, confirm this. Although events like the one in Lisbon have been repeated more or less throughout history, we tend to associate tsunamis with phenomena more typical of other places on the planet, such as the Pacific Ocean, where large earthquakes are more frequent. These phenomena can be caused.
Tsunami risk areas in Spain
The researchers explain that a document has been prepared at the state level in which the areas most vulnerable to the tsunami were identified, that is, all the coasts of Spain, with the exception of Asturias and Cantabria, where the impact is less. “It is unlikely to happen in these areas because there are no faults. These are found in the Gulf of Cádiz, northern Algeria, northern Africa, and elsewhere. Therefore, Studies must be carried out at the community and municipal levels.
Spain currently has a Citizen Protection Plan against tsunami risks, which the Government will prepare and approve in May 2021. As explained in the text published in the Official State Gazette (BOE), it is the “ tsunami warning system” to inform the civil protection authorities and public emergency services of the urgency of the aforementioned threat, as well as the citizens who may be affected”, Although it only elaborated “basic planning guidelines for the protection of civilians against tsunami risks”.
In addition, the National Geographic Institute of Spain (IGN) also has a tsunami warning system that is operational and sends tsunami warning messages to the population in case of risk. But cities potentially affected by the tsunami must have action plans.
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 fault lines that separate the Eurasian plate from the African plate. In addition, it highlights that Spain was already affected by the Lisbon earthquake of 1755, which originated in the depths of the sea. The resulting tsunami wreaked havoc on 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.
I hope that with this information you can learn more about the tsunami risk in Spain and how to prepare for it.