Characterizing an Incipient Transtensional Fault System: Insights from
the Morphometric Analysis of the North-South Faults (Alboran Sea)
Abstract
Geomorphological studies are significant for understanding fault
dynamics and assessing their seismic hazard, particularly in offshore
regions where direct observation is limited. The North-South Faults
(NSF), analyzed using ultra-high-resolution bathymetric data, reveal a
complex seafloor expression characterized by multiple fault scarps and
pockmarks. Through geometric analysis of morphotectonic parameters along
the fault segments, we identified patterns of fault growth and
segmentation, with a particular focus on transfer zones and intricate
fault linkages. Cumulative vertical displacement varies from centimeters
to decameters, with the largest displacements typically observed in the
northern sections of the fault segments. These height variations, along
with segment lengths and linkage patterns, indicate northward fault
propagation, suggesting the NSF is in the early stages of development
within a left-lateral transtensional system. Furthermore, our findings
support the interpretation of the NSF as the northern extension of the
Al-Idrissi Fault, emphasizing its significance for seismic hazard
assessment in the region. Finally, we propose that NSF may represent a
potential seismic source for a magnitude 6.1 Mw earthquake and suggest
it as an alternative source of the 1910 Adra earthquake. This study
offers new insights into the early growth and evolution of
transtensional fault systems worldwide and their associated seismic
potential.