Tsunami generation potential of a strike-slip fault tip in the westernmost Mediterranean

F Estrada,G Ercilla,J M González-Vida,J T Vázquez,S Ortega,J Macías,J Galindo-Zaldívar,J A Peláez

doi:10.1038/s41598-021-95729-6

Abstract

Tsunamis are triggered by sudden seafloor displacements, and usually originate from seismic activity at faults. Nevertheless, strike-slip faults are usually disregarded as major triggers, as they are thought to be capable of generating only moderate seafloor deformation; accordingly, the tsunamigenic potential of the vertical throw at the tips of strike-slip faults is not thought to be significant. We found the active dextral NW–SE Averroes Fault in the central Alboran Sea (westernmost Mediterranean) has a historical vertical throw of up to 5.4 m at its northwestern tip corresponding to an earthquake of Mw 7.0. We modelled the tsunamigenic potential of this seafloor deformation by Tsunami-HySEA software using the Coulomb 3.3 code. Waves propagating on two main branches reach highly populated sectors of the Iberian coast with maximum arrival heights of 6 m within 21 and 35 min, which is too quick for current early-warning systems to operate successfully. These findings suggest that the tsunamigenic potential of strike-slip faults is more important than previously thought, and should be taken into account for the re-evaluation of tsunami early-warning systems.

Highlights

Tsunamis are triggered by sudden seafloor displacements, and usually originate from seismic activity at faults
The Alboran Sea is deformed by strike-slip faults under laterally unlocked tectonic indentation driven by Eurasian-African plate convergence[15] at a rate of 4.5 mm/ yr[16] (Fig. 1) The Alboran Sea, whose Iberian coast annually receives the highest number of tourists from all of Europe, has been historically afflicted by tsunamis[17,18,19]
The Averroes Fault is a component of the NW–SE conjugate dextral strikeslip fault set of the main NNE-SSW shear zone crossing the Alboran Sea[15] (Fig. 1b)

Summary

Introduction

Tsunamis are triggered by sudden seafloor displacements, and usually originate from seismic activity at faults. Strike-slip faults are usually disregarded as major triggers, as they are thought to be capable of generating only moderate seafloor deformation; the tsunamigenic potential of the vertical throw at the tips of strike-slip faults is not thought to be significant. Waves propagating on two main branches reach highly populated sectors of the Iberian coast with maximum arrival heights of 6 m within 21 and 35 min, which is too quick for current early-warning systems to operate successfully These findings suggest that the tsunamigenic potential of strike-slip faults is more important than previously thought, and should be taken into account for the re-evaluation of tsunami early-warning systems. Subsequent modelling the tsunamigenic potential of this structure reveals the potential for tsunami generation triggered by vertical offset at the tip of a strike-slip fault, providing knowledge crucial for reviewing potential tsunami hazards related to strike-slip faults worldwide

Methods

Results

Conclusion