EGU22-514, updated on 26 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Seafloor expression of the deep structure during initiation of transtensional fault systems, as seen in the North-South fault system of the Alboran Sea, SE Iberia.

Ariadna Canari Bordoy1, Hector Perea2, Sara Martínez - Loriente1, Eulàlia Gràcia1, David Fernández - Blanco1, and Jaume Llopart1
Ariadna Canari Bordoy et al.
  • 1Institute of Marine Sciences - CSIC, Marine Geosciences, Barcelona, Spain
  • 2Complutense University of Madrid, Madrid, Spain

How fault segments grow and connect in regions with moderate to high seismic activity is key to assess associated hazards. Earthquakes may affect populated areas and can trigger tsunamis that threaten coastal areas and affect marine infrastructures. Regions accommodating relatively slow tectonic deformation may still enclose active fault systems capable of generating moderate to large magnitude earthquakes, albeit at long recurrence intervals (103 to 104 years). Although the Alboran Sea is currently characterised by slow tectonic deformation and by earthquakes of low to moderate magnitude, large historical and instrumental events have also occurred (i.e., the Almeria 1522 IEMS98 VIII-IX or the Al-Idrissi 2016 Mw 6.4 earthquakes). This Neogene basin located in the westernmost Mediterranean Sea absorbs most of the convergence between the Eurasian and Nubian plates (3 - 5 mm/year) by means of four tectonic-scale fault systems: the Carboneras and Al-Idrissi left-lateral strike-slip faults, the Yusuf right-lateral strike-slip fault and the Alboran Ridge thrust.

Our study characterises the North-South fault system on the northern Alboran Sea to better understand the kinematics of the region on a larger scale. This system is proposed as the northern termination of the Al-Idrissi fault, and it may be presently evolving due to the transtensional stress field that affects the area. The first step to characterise the fault system has been to elaborate a detailed geomorphological map of the area to describe the identified scarps, their distribution, and structural relations. To achieve this, we have used very high-resolution bathymetric data (1x1 m pixel resolution) acquired with an autonomous underwater vehicle. The bathymetry shows several fault scarps striking N-S, resulting in horst and graben systems. The second step has involved the interpretation of high-resolution multichannel airgun and sparker seismic profiles running across the N-S faults. The integration of this dataset allows us to relate the morphological scarps with different normal faults interpreted in the seismic profiles. These faults cut the post-Messinian seismostratigraphic units (last 5.3 Ma) up to the seafloor, which supports that the fault system is currently active. Finally, the high segmentation of the North-South fault system and its small accumulated fault displacements supports it is in its initial stage of evolution.

How to cite: Canari Bordoy, A., Perea, H., Martínez - Loriente, S., Gràcia, E., Fernández - Blanco, D., and Llopart, J.: Seafloor expression of the deep structure during initiation of transtensional fault systems, as seen in the North-South fault system of the Alboran Sea, SE Iberia., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-514,, 2022.