What are the real chances of a tsunami in Spain?

by Deborah Cater
Tsunamis are a real possibility in Spain

The risk of a tsunami in Spain is real. This is not about doom and gloom, but about scientific conclusions. The Ministry of Interior has therefore approved the State Plan for Civil Protection against Tsunami Risk.

That’s insurance for coastal protection. Until now, there was not even that, despite the fact that 23 million people live in the area where, according to experts, a tsunami could occur. That is 58% of the population in an area of ​​7,660 square kilometres. After years of delay and the deployment of specialists, the State Plan places Spain at the forefront of Europe in this area.

‘Unique’ coordination work

The aim of the plan is to detect phenomena as early as possible; and inform the population to proceed with evacuation and self-protection before the water reaches land. It seems simple, but according to Minister Grande-Marlaska, behind it lies a “unique” coordination work between state and regional governments. It is based on the National Tsunami Warning System and information from the National Seismic Network, the tide gauges of the ports or the detection systems of the Spanish Oceanographic Institute.

Potentially devastating impact

Every effort has been made to determine where, when and how these gigantic waves could arise. They travel thousands of kilometres at speeds between 500 and 1,000 kilometres per hour, with potentially devastating impacts.

The plan also includes a study of potential risks for different parts of the Spanish coast. Everything depends on the proximity and movement of the nearest tectonic plates. On average, it takes about an hour from when a tsunami starts and it hits the coast. However, it takes ten minutes to detect it and another seven minutes to calculate where the waves will hit and what will flood.

Biggest risk area’s west coast Andalucia and Canary Islands

According to this plan, there are three risk zones in Spain. The most dangerous are the coasts of the province of Huelva, western Cádiz and the Canary Islands. The Mediterranean is a medium risk area and the Cantabrian coast is least at risk.

The highest tidal wave increases are said to occur on the west coast of Andalucia and in the Canary Islands. The findings point to tidal waves of up to eight metres, with arrival times ranging from 55 minutes for western Andalucia to an hour for the islands. In the case of Andalucia, smaller tsunamis can also occur, with an arrival time of half an hour.

Andalucia

On the Andalucian Mediterranean coast, it is the southern Alboran fault to watch out for. Waves of five meters can be generated in Malaga and Melilla, with an arrival time of 20 minutes. The arrival in the Mediterranean along Spain’s east coast is almost instantaneous due to fault lines that are very close to land or even partly formed on land. However, a tsunami there would be much smaller (up to 1 metre high).

East coast

In the northern part of the Murcia coast, waves of two meters are expected to arrive in 30 minutes due to the La Marina fault. The Balearic Islands should especially keep an eye on the northern stretch of Mallorca and Menorca, due to the Barcelona-Tarragona riftl. There the waves would have a height of 0.6 meters and arrival in 20 minutes. Ceuta has 20 minutes to respond for expected 1.2 metre rises through the Jebha Fault.

Northwest Spain

In Galicia, a tsunami near the Gorringe Ridge can have a maximum height of two metres; but it takes longer – up to an hour – to reach the coast. Along the rest of the Cantabrian coast, waves are less than half a metre. Therefore, this zone falls outside the scope of the new plan.

24 tidal waves registered in history

It’s happened before, and it could happen again. According to the National Geographic Institute, 24 tidal waves have been recorded in Spain since 218 BC. Those on the coast of Cádiz and Huelva weighed the most in drawing up the plan.

cogesa expats

In 1755, large areas – especially in the capital Cadiz – were flooded and 2,000 people were killed. The tsunami was caused by the Lisbon earthquake that killed 15,000. That tsunami was the worst known in Spain. There were waves of 15 metres that found no obstacles even in the walls of the ancient cities. This tsunami did not go inland once, but came ashore a total of 3 times by force.

 The geography of the area, with a flat coastline and hardly any elevation, meant the waves penetrate the land up to a kilometre. The effects of a tsunami in the same spot could be more severe now, as the population and infrastructure has multiplied compared to nearly 300 years ago.

Graphic examples

The Edanya research group at the University of Malaga is internationally recognised for its contributions to mathematical modelling and numerical simulation of tsunamis. It is the European leader in the field. It has produced graphical examples of the damage from possible tsunamis. Anyone who wants to downplay the risk of tsunamis in certain places in Spain will be disappointed. The first seconds pass, it seems as if nothing is happening, and then comes the flood.

The last tsunami in Spain was in 2003

The last tsunami in Spain was on May 27, 2003. An earthquake off the Algerian coast caused a small tsunami, with waves reaching the Balearic Islands, such as Palma de Mallorca and Mahón in Mallorca. The tsunami was no higher than 15 centimetres, but did cause damage to several boats.

“When’s the next one coming?”

The key question is ‘when will the next one come?’ Scientists don’t have the answer and acknowledge that in the government’s plan. This only prepares for a real risk. No one knows if it will come, how and when.

According to geologist Alejandro Fernández, Spain lies in a “major” seismic zone, a contact area between the African and European plates. Spain alone doesn’t even come close to places like Japan or the Pacific Ring of Fire where 81% of the world’s largest earthquakes occur. The risk for Spain in that regard is ‘moderate or low’, says Fernández. “Even the recent chains of tremors in Granada or Murcia show that the earth is moving at our feet, but without great ferocity”.

Importance of detection systems

It is difficult to know in advance what is to come, because “normally there are successive waves, one of which has an even greater destructive power than the first”; hence the importance of detection systems such as those now approved by the Ministry.

What to do in case of a tsunami

For now, the approval of the new plan has already activated the residents of the affected areas. They are refining information and warning protocols. In Cádiz there are neighbourhood associations such as Segunda Aguada, which have established their own action councils. For example, they make evacuation plans whose aim is to get residents away from the coast to areas higher than 10 metres above sea level.

However, if the time is minimal, the advice is vertical evacuation: enter buildings that are high enough and then make your way to a height of at least 30 metres. To this end, those buildings with sufficient resistance to tsunamis must be identified everywhere.

‘False pauses’

Direct impact damage, flood damage and wave erosion can occur if the water returns to the sea with a force of 100 kilometres per hour. The force of the tsunami can topple buildings and transport very heavy objects, such as rubble and cars. And it’s also important to take ‘false breaks’ into account. Sometimes a single wave is thought to come, people relax and even go to the coast to see the effects; and then more waves come with all the dramatic consequences that entails. A tsunami can produce 10 or more destructive waves for 12 hours.

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