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The Averroes fault in the Alboran Sea: a real tsunami risk for Spain's Mediterranean coast

Tsunami propagation model of the Andalusian coast.
Tsunami propagation model of the Andalusian coast. / ICM-CSIC
  • A new CSIC study places it very close to the Andalusian coast and points to a potential to generate tidal waves greater than previously believed

Could the Mediterranean coast, in the south of Spain, be hit by a tsunami? Although the probability is very small, the reality is that the danger exists. In fact, there is a State Civil Protection Plan for the risk of a tsunami in which Malaga is marked in red.

Now, a study led by researchers from the Higher Council for Scientific Research (CSIC) has discovered that directional jump faults, such as the Averroes fault - offshore from Malaga, Granada and Almeria - in the Alboran Sea have more potential to generate coastal tsunamis than previously believed.

The work, published in the 'Scientific Reports' journal, analyses this active fault and reveals the nearby coastal areas that could be affected by the arrival of tsunami waves, as well as the magnitude.

Ferran Estrada, an expert from the Institute of Marine Sciences (ICM-CSIC), said "the Averroes fault presents, in its extreme northwest, a vertical jump of up to 5.4 metres", which "could generate a magnitude 7 earthquake”. This is known after analysing the activity of the fault of the last 124,000 years. According to historical records, the last earthquake generated by this fracture may have been in the year 365.

Thanks to a mathematical model of the deformation of the sea floor, the team of researchers has calculated the behaviour of the water masses of the Alboran Sea in the event of a new seismic episode on the fault. According to this simulation of possible scenarios, the tsunami waves would spread in two main branches and reach and flood heavily populated sectors of the southern coast of Spain and northern Morocco. These waves could reach six metres in height and would take between 21 and 35 minutes to reach the coast.

"These episodes are too fast for current early warning systems to work successfully," the scientist warned. In his view, these findings show the potential for tsunami generation of jump faults 'should be considered' for the reassessment of tsunami early warning systems'. As the CSIC points out, until now it was believed that tsunamis originate from the seismic activity of normal and reverse faults; while the direction jump, which separate blocks that move laterally, were discarded as triggers.

Estrada warns that "giant waves can represent a threat to coastal populations, damage marine and land infrastructure, and cause an economic and environmental crisis." That is why, according to the scientist, these results will be "vital to improve planning measures aimed at mitigating the impact of a possible tsunami."