Quaternary active tectonic structures in the offshore Bajo Segura basin (SE Iberian Peninsula – Mediterranean Sea)

Abstract

Abstract. The Bajo Segura fault zone (BSFZ) is the northern terminal splay of the Eastern Betic shear zone (EBSZ), a large left-lateral strike-slip fault system of sigmoid geometry stretching more than 450 km from Alicante to Almería. The BSFZ extends from the onshore Bajo Segura basin further into the Mediterranean Sea and shows a moderate instrumental seismic activity characterized by small earthquakes. Nevertheless, the zone was affected by large historical earthquakes of which the largest was the 1829 Torrevieja earthquake (I EMS98 X). The onshore area of the BSFZ is marked by active transpressive structures (faults and folds), whereas the offshore area has been scarcely explored from the tectonic point of view. During the EVENT-SHELF cruise, a total of 10 high-resolution single-channel seismic sparker profiles were obtained along and across the offshore Bajo Segura basin. Analysis of these profiles resulted in (a) the identification of 6 Quaternary seismo-stratigraphic units bounded by five horizons corresponding to regional erosional surfaces related to global sea level lowstands; and (b) the mapping of the active sub-seafloor structures and their correlation with those described onshore. Moreover, the results suggest that the Bajo Segura blind thrust fault or the Torrevieja left-lateral strike-slip fault, with prolongation offshore, could be considered as the source of the 1829 Torrevieja earthquake. These data improve our understanding of present deformation along the BSFZ and provide new insights into the seismic hazard in the area.

How Much Nubia‐Eurasia Convergence Is Accommodated by the NE End of the Eastern Betic Shear Zone (SE Spain)? Constraints From GPS Velocities

“…The main active structures of this fault zone are two ENE‐WSW‐striking reverse blind faults, the Torremendo and Bajo Segura Faults, and several secondary NW‐SE‐striking dextral faults (the San Miguel de Salinas, Torrevieja, and Guardamar Faults). These structures continue offshore eastward (Alfaro, Delgado, et al, ; Perea et al, ).…”

Compressional tectonic inversion of the Algero-Balearic basin: Latemost Miocene to present oblique convergence at the Palomares margin (Western Mediterranean)

“…Main tectonic structures associated to the late Miocene (post latemost Tortonian) to present‐day compressional tectonic inversion of the Betics, Rif, Alboran, and Algero‐Balearic basins, both onshore and offshore. The fault traces and kinematic data are taken from previous authors [ Martínez‐Díaz et al , ; Booth‐Rea et al , , ; Masana et al , ; Booth‐Rea et al , ; Marín‐Lechado et al , ; Masana et al , ; Domzig et al , ; Gràcia et al , ; Pedrera et al , ; Moreno et al , ; Pedrera et al , ; Sanz de Galdeano et al , ; Gràcia et al , ; Alfaro et al , ; Pedrera et al , ; Perea et al , ; Sanz de Galdeano et al , ; Giaconia et al , ; Maillard and Mauffret , ; Martínez‐García et al , ; d'Acremont et al , ]. AbF, Abubacer fault; AlF, Al‐Idrisi fault; AMF, Alhama de Murcia fault; ARF, Alboran Ridge fault, BFS, Baza basin fault system, BSFZ, Bajo Segura fault zone; CFZ, Carboneras fault zone; GrFS, Granada basin fault system; GuFS, Guadix basin fault system; PFZ, Palomares fault zone; PoFZ, Polopos fault zone; TFZ; Terreros fault zone; XB, Xauen bank; YF, Yusuf fault.…”

Acoustic and seismic imaging of the Adra Fault (NE Alboran Sea): in search of the source of the 1910 Adra earthquake

“…This active fault system runs along more than 450 km, and its terminal splays (i.e. the Bajo Segura Fault to the northeast and the Carboneras Fault to the southwest) extend into the sea (Comas et al, 1999;Alfaro et al, 2002;Gràcia et al, 2006;Moreno et al, 2008;Moreno, 2011;Perea et al, 2012) (Fig. 1).…”