Cristina Hodgson
LARGE parts of the coast of Andalucia and northern Morocco could be hit by waves of up to six metres from a large tsunami, experts warn.
This is not the first time alarm bell have sounded warning that a seismic movement in the Alboran Sea could generate six metre waves that would only take between 21 and 35 minutes to reach the coast, however a recent study, published last week in the journal ‘Scientific Reports’, warns that new variables, such as fault morphology, need to be taken into account, in tsunami early warning systems.
The study, led by researchers at the Institut de Ciencies del Mar (ICM-CSIC), has found that strike-slip faults have more potential to generate coastal tsunamis than previously thought.
The work, led by ICM geologist Ferran Estrada, has analysed the active Averroes strike-slip fault located in the Alboran Sea. Strike-slip faults, which separate laterally moving blocks, are usually ruled out as tsunami triggers and by doing so, Estrada believes that current alert systems would not be quick enough to pick up on the fault movement and that new variables, such as fault morphology, need to be taken into account in tsunami early warning systems.
“The Averroes fault has, at its northwest end, a vertical jump of up to 5.4 metres that would have generated a magnitude 7 earthquake. We have studied the activity of the fault over the last 124,000 years and, according to historical records, the last earthquake generated by this fracture may have been in 365 AD”, Estrada said.
Using a mathematical model of the deformation of the sea floor, the research team has calculated the behaviour of the water masses in the Alboran Sea in the event of a new seismic event on the fault.
According to this scenario simulation, tsunami waves would propagate in two main branches and reach and inundate densely populated areas of the southern coast of Spain and northern Morocco. These waves could be up to six metres high and would take between 21 and 35 minutes to reach the coast.
“These are episodes that are too fast for current early warning systems to operate successfully. These findings indicate that the tsunami-generating potential of strike-slip faults should be taken into account for the re-evaluation of tsunami early warning systems”, concludes the ICM researcher.
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