• A large-scale tsunami could happen anywhere on the planet.

 

• The earthquake in Cádiz in 1755 (Mw ~ 8.5-9-0) caused a tsunami which caused more than 15,000 deaths, nowadays that number would be similar to the Tsunami in Indonesia in 2004. 

 

• Areas like Almería and Murcia and areas in the Balearic Isles would be flooded with waves reaching over 3m.

 

• In Spain there is a high risk of tsunamis, but there are no plans or emergency protocols, nor relief services or preparation for the exposed population.

 

• If there were a tsunami opposite Algiers, in less than 30 minutes the Costa del Sol area would be affected by waves which could be of great importance.

 

 

 

 

 

 

 

 

THE UNESCO MEETING

 

 

 

Today was the closing ceremony in the UC Institute of Environmental Hydraulics of the annual meeting between the inter-governmental groups of the UNESCO work groups for the creation of analogical systems in the Indian Ocean (IOTWS), the North-East Atlantic and the Mediterranean (NEAMTWS) and the Caribbean (CARIBE EWS).

 

This is the first time a NEAM meeting has taken place.  The tsunami catastrophe in the Indian Ocean in December 2004 showed one fact; only the Pacific Ocean had a system to alert tsunamis.  That’s why UNESCO set up a series of inter-governmental work-groups for the creation of analogical systems in the Indian Ocean (IOTWS), the North-East Atlantic and the Mediterranean (NEWMTWS) and the Caribbean (CARIBE EWS); besides, the three groups are also working on the integration between different regions on a warning system on a world-wide scale. 

 

In the annual meeting like the one in Santander, there are committees from over 40 countries, with participation from more than 80 representatives, some observers from countries such as the USA (NOAA), Japan, etc.  Most of them are scientists (geologists, physicists, seismologists, engineers, experts in instrumentation and communication, natural risks, etc) and administrative agencies (civil protection, central, regional and local administrations….)

 

Of the various groups which form part of this committee there are two which are coordinated by Spanish entities; one of them by Begoña Pérez from the Spanish Port Authority, which heads the Instrumentation group to detect tsunamis, and the other is Mauricio González from the UC Institute of Hydraulics, which manages the group of numerical modeling and estimation of the dangers of tsunamis.

 

Each country-member has a governmental entity which is a contact point for UNESCO, through which the activities of each country are coordinated.  In Spain, this is the Spanish Oceanography Institute (IEO).  The Spanish committee is made up of scientists who are in IEO, the National Geographic Institute (which controls the seismology network of the country), the Spanish Port Authority (which controls tide gauges and buoys in Spain), Civil Protection, the Navy and IH Cantabria.

 

 

 

 

 

 

Historically speaking, the Spanish coasts have suffered the impact of tsunamis, the coastal areas which are most affected are those found on the Atlantic basin (south-west) and the Mediterranean coast.  The tsunamigenic seismic areas (where tsunamis form) are located on the bordering areas between the tectonic African and Euro-Asiatic plaques, as shown in Figure 1 with red bands.  With regards to the Atlantic basin, according to the European catalogue of tsunamis, more than 18 tsunamigenic earthquake have historically taken place between 300 B.C. and 1900, and took place in the area of the Gulf of Cádiz.

 

Of all these tsunamis, we must highlight two particularly catastrophic events, such as the 1531 one (Mw ~ 8.5-9.0), which caused more than 15,000 deaths (see the location of the epicenter next to other historical events in Figure 1).  After sedimentological studies were carried out (paleo-tsunamis), a great amount of historical events on a large scale in that area have been shown, particularly the occurrence of two large-scale tsunamis in 200 B.C. and 60 B.C., which had an important effect on the area around the Gulf of Cádiz.

 

Figure 1. The principal areas where tsunamis are generated on Spanish coasts (the red bands correspond to tsunamigenic seismic areas) and the location of epicenters of historical earthquake events which caused tsunamis (Committee for Atomic Energy in France, CEA).

 

The tsunami phenomena and its impact on the Spanish coast has been widely studies by the scientific community. Spanish groups have carried out paleo-tsunami studies which have allowed them to identify historical events and how often they have occurred.  On the other hand, a reduction has been reached in the calculation times of seismic moment tensor to predict the main mechanisms after they are detected in the Spanish seismic system, an essential aspect in a tsunami warning network.

 

Potential tsunami generation points affecting the Spanish coast have already been characterized; developing methodologies to assess risk and danger with regards to the Spanish coast; new numerical flooding models have been validated to elaborate flood maps, vulnerability and risk in trial areas such as the city of Cádiz, Huelva and the Balearic Isles, but these should be extended to the rest of the Spanish coast. Automatic algorithms in real time to detect tsunamis with tide gauges have also been developed, and these have been implemented with the Network of Tide Gauges (REDMAR) by the Spanish Port Authorities.

 

 

 

It is necessary to assess the danger and risk when faced with tsunamis along the Spanish coast in order to reduce the risk for the exposed population through the implementation of a local warning system on Spanish coasts and programmes to educate and prepare people.

 

 

 

MEDITERRANEAN

 

 

 

With regards to the Western Mediterranean Basin (Málaga, Granada, Almería, Murcia and the Balearic Isles), the main area which generates “nearby” tsunamis is the area in the North of Algiers (see Figure 1).  Historically in this area, there have been events with a greater frequency, compared with the frequency of tsunamis in the Atlantic Basin.  Although tsunamis in this area are not as disastrous as those which occur in the Atlantic Basin, they are however capable of flooding lower areas on the coast.  Recent studies show that some areas such as Almería, Murcia and the Balearic Isles, could become flooded by waves which are higher than 3m, highly dangerous tsunamis which are dangerous for swimmers and tourists staying in these areas during the summer period.  To this we must also add operational problems in ports, even occurring by tsunamis of a low-magnitude, fundamentally due to the effects of local resonances, causing boats in mooring areas to sink and increasing the risk of environmental contamination (oil and fuel terminals), the same as what happened during the recent tsunami in Algiers in 2003, but on a lesser scale.  Besides these “nearby” tsunamis, the Spanish Mediterranean coast is also exposed to tsunamis in the Eastern Basin of the Mediterranean (the Aegean Sea), where more than 250 tsunamis have been registered in the last 3,500 years.  Some of them were high-magnitude tsunamis such as those in the complex of volcanic isles of Thera (Santorine) (1630 B.C., 1650 B.C., 1956), and those in the Hellencic Arch (365, 1303, 1741), among others.

 

 

 

ATLANTIC

 

 

 

From these studies, we can emphasize that the Spanish coast shows a high risk with regards to tsunamis in the area of the Gulf of Cádiz, with a medium-low risk on the Mediterranean coast.  A tsunami similar to the one in 1755 in the Gulf of Cádiz, which nowadays would be during the summer season, would cause a catastrophe that is similar or greater to the one in Indonesia in 2004, given the enormous activity on the coastal area and the number of tourists during the summer period.  Besides, we have to take into account that there are no emergency plans nor measures of education or preparation for people in the exposed areas on the Spanish coast, unlike what may occur in countries such as Japan, which considerably helped to lower the numbers of casualties in the area.

 

 

 

THE NEED FOR A NATIONAL AND REGIONAL WARNING SYSTEM

 

 

 

Apart from the regional integration (and even global integration) of data coming from the creation of Regional and Global Warning Systems (one of the objectives of this work-group), it is essential for each country or state member to have its own National Warning System for several reasons: in the first place, because only a dense network on a national level could be effective with regards to a nearby or local tsunami and the majority of countries, especially those on the Mediterranean, are exposed to this type of incident.  On the other hand, warnings to the population and emergency protocols and plans are a national matter; Regional or Global Warning Systems will be limited to sending warnings to National Systems when an incident occurs and is considered to affect its coasts, but apart from this, the responsibility corresponds to each country.  This is the most difficult thing to achieve, and it partly explains the errors detected in recent tsunamis such as the one in Indonesia in October 2010.  The arrival times of the “nearby” tsunamis depend on the location of the origin, with typical times of 45 and 60 minutes in the area of the Gulf of Cádiz, and with times of between 20 and 60 minute on the Mediterranean coast.

 

On the other hand, several countries such as France, Portugal, Italy or Greece have suggested becoming Regional Centres, which means that the first two have already been in contact with Spanish institutions to gain access to our data in seismic and tide gauge stations in real time.  The French Government has recently passed an investment of 12.6 Million Euros to establish its system, which will be the responsibility of the AEC (Atomic Energy Committee in France); its objective is for it to be operative in 2012.

 

 

 

After a tsunami has occurred, NEAMTWS, the regional system, or the French system will allow Spain to find out that a “distant” tsunami (in Greece or Turkey) has taken place or a “nearby” one (in Algiers or the Gulf of Cádiz”), but they wouldn’t know what to do with this warning, given that the areas where the magnitude of the impact of the tsunami and the arrival times would be unknown.  That’s why it is important, first of all to take precautionary measures, which means assessing danger and the risk of tsunamis along the Spanish coast, in such a way that it would allow mitigation measures to be implemented at a local level in the more exposed areas and prepare people with regards to the incident.  Secondly, to establish a warning system with established emergency plans which would allow the population to be protected during and after a tsunami.

 

 

 

The majority of the countries which are exposed to tsunamis in the Mediterranean basin are already taking precautions and beginning to establish local warning systems, except for Spain where there is no initiative in the central or regional government. Furthermore, in Spain there is no legal framework which makes any institution have as a mandate the authority to watch out for any danger of tsunamis, nor the installation and maintenance of a Tsunami Warning System.

 

In Spain there is a high risk of tsunamis, there are no emergency plans or protocols, nor means of mitigation and preparation for the exposed population. In 2012, we will be able receive a warning message from NEAMTWS, the international system, or the French system, but we will not know what to do with this warning, where to evacuate people if we have to do so, nor how long it would take, we wouldn’t know what to do.