Recent and active faults and folds in the central-eastern Internal Zones of the Betic Cordillera

The most recent tectonic structures of the central-eastern Internal Zones of the Betic Cordillera (from 3.1oW to 1.7oW and to the south of 37.525oN) include fault and folds developed from the Late Miocene onwards, which are related to N-S/NW-SE directed continental collision and moderate thickening of a crust that is relatively hot at depth. In this setting, E-W to WSW-ENE folds, with locally associated E-W transpressive right-lateral and reverse faults, favoured the emersion of the northern Alborán basin palaeomargin and the progressive intramontane basin disconnection. The NNE-SSW to NE-SW trending regional left-lateral Palomares and Carboneras fault zones are dominant structures in the easternmost part of the cordillera. In addition, NW-SE to WNWESE trending normal and oblique-slip normal faults are widespread. The collision is still active and continues to drive active folds and faults, some probably being the likely source of moderate-sized earthquakes. The Campo de Dalías and surrounding sectors, deformed by active ENE-WSW folds and NW-SE to WNW-ESE oblique-slip normal faults, are probably the sites with the largest at fairly regular intervals, in 1804, 1910, and 1994. Toward the east, NW-SE trending normal faults extending from Almería to the Tabernas basin deform the Quaternary rocks with associated moderate seismicity (the 2002 Gergal Mw 4.7 earthquake, and possibly the 1894 Nacimiento earthquake, felt with intensity VII). In the Sorbas-Vera basin, the Palomares fault zone is also responsible for moderate-sized earthquakes (1518 Vera earthquake). In the Almanzora corridor, NW-SE to WNW-ESE trending Lúcar-Somontín faults also could be considered one of the possible source of moderate-magnitude seismicity (1932 Lúcar, Mw 4.8 earthquake felt ISSN (print): 1698-6180. ISSN (online): 1886-7995 www.ucm.es /info/estratig/journal.htm Journal of Iberian Geology 38 (1) 2012: 191-208 http://dx.doi.org/10.5209/rev_JIGE.2012.v38.n1.39213 192 Pedrera et al. / Journal of Iberian Geology 38 (1) 2012: 191-208


Introduction
The recent and active tectonic structures of the Betic Cordillera have attracted attention of Earth scientists since the 1970s (Andrieux et al., 1971;Biju Duval et al., 1977;Groupe de Recherche Neotectonique, 1977;Bousquet and Montenat, 1974;Bousquet and Phillip, 1976;Bousquet, 1979), and since then, much geological and geomorphological research has been focused on WKHLU LGHQWL¿FDWLRQ LQ RUGHU WR HVWDEOLVK WKH PHFKDQLVPV responsible for the tectonic evolution of the orogen (e.g., Sanz de Galdeano, 1983;Ott d'Estevou and Montenat, 1985;Sanz de Galdeano, 1990) and to estimate their seismogenic potential (e.g., Sanz de Galdeano and López Casado, 1988;Sanz de Galdeano et al., 1995).While the location, geometry, and kinematics of the main structures are well established, the processes involved in their development and the present-day activity of some of these structures are still under debate.It is widely accepted that compressional and extensional structures have deformed the Internal Zones of the Betic Cordillera since the Late Miocene.This region exhibits a variety of deformational styles, dominated by folds, right-lateral and normal faults in the central Betics (e.g., Galindo-Zaldívar et al., 2003), and by large left-lateral strike-slip faults in the eastern sector of the cordillera that also interact with folds and normal/normal-oblique faults (e.g., Martínez-Díaz, 2002;Masana et al., 2004;Booth-Rea et al., 2003;Pedrera et al., 2010a).The present study attempts to sketch a coherent picture of these recent tectonic structures that deform the central-eastern (from the longitude 3.1ºW to 1.7ºW and to the south of 37.525ºN) Internal Zones of the Betic Cordillera (Fig. 1).Special attention is placed on the faults and folds that have been active during Quaternary times, which are potential sources of future earthquakes.

Geological setting
The Betic Cordillera, together with the Rif, constitutes the westernmost part of the Alpine Mediterranean belt in the convergent Eurasian and African plate boundary (Fig. 1A).The Alpine evolution of the orogen is determined by the interaction between the two major plates and the intermediate placed Alborán Domain (Internal with intensity VIII).Toward the east, between Albox and Partaloa, several small reverse faults and associated compressive structures GHIRUP 4XDWHUQDU\ DOOXYLDO DQG ÀXYLDO VHGLPHQWV $OWKRXJK VRPH RI WKHVH IROGV UHYHDO D VORZ DQG SURJUHVVLYH GHIRUPDWLRQ IURP WKH Middle Pleistocene onwards, some of these reverse fault segments that deform the western Huércal-Overa basin could host the 1972 NW Partaloa, mbLg 4.8 earthquake, felt with intensity VII.Keywords: Active Tectonics; Earthquakes; Tectonic Evolution; Gibraltar Arc.
In the Betic Cordillera, the structures that formed since the late Miocene up to now have been classically designated as recent or neotectonic.These structures determine the spatial distribution of the uplifted areas subjected to erosion and the sedimentary basins.Below, we describe the recent and active structures that, from north to south, deform the Almanzora corridor and the Huércal-Overa basin, the Alpujarran corridor and the Tabernas, Sorbas, and Vera basins, and the Campo de Dalías and the Almería-Níjar basin (Fig. 1B).

The Almanzora corridor and the Huércal-Overa basin
The Almanzora corridor and the Huércal-Overa basin are located between the Sierra de Los Filabres and Sierra de Las Estancias (Figs 1 and 2).Both basins are essen-WLDOO\ ¿OOHG E\ 6HUUDYDOOLDQORZHU 7RUWRQLDQ FRQWLQHQWDO ÀXYLDOGHOWDLF VHGLPHQWV DQG EHFDPH D PDULQH UHDOP GXring the late Tortonian.The marine-continental transition started in Messinian times.Continental sedimentation along rivers and alluvial fans together with erosion occurred during the Pliocene and Quaternary.

Active tectonic structures
The westernmost part of the Almanzora corridor is affected by a set of NW-SE faults that deform up to the Quaternary glacis and constitute the western end of the corridor.These fault segments are related to the normal Baza fault (Alfaro et al., 2008;García-Tortosa et al., 2008;Sanz de Galdeano et al., this volume), which extends more than 30 km along the Baza basin, showing a N-S to NW-SE variable strike, and dipping to the NE (Fig. 1B).In the central part of the corridor, the Lúcar faultformed by a set of ENE-WSW oriented and 40º-75º south dipping normal faults-locally deforms the Quaternary sediments.Close to Somontín, the Quaternary sediments are deformed by a NW-SE oriented high-dipping fault Augier, 2004;Augier et al., 2005;Meijninger and Vissers, 2006;Pedrera et al., 2007;Pedrera et al., 2010a).The study area was deformed by a succession of kilometric scale folds with orientations ranging from E-W to ENE-WSW: the Sierra de Los Filabres and Sierra de Almagro antiforms, Almanzora corridor synform and Sierra de Las Estancias antiform (Booth-Rea et al., 2003, 2004;Pedrera et al., 2007Pedrera et al., , 2009b)).The antiforms coincide with the ranges where the metamorphic rocks crop out, while the synforms correspond to the sedimentary basins.Folding started there with the Sierra de los Filabres antiform nucleation during Serravallian-early Tortonian, as revealed by the syntectonic angular unconformities founded in its northern limb (Pedrera et al., 2007).Large-scale folds continued growing and propagating to the north, forming the Almanzora corridor in the late Tortonian (Pedrera et al., 2007).Moreover, the sedimentary rocks have been deformed since late Tortonian by ENE-WSW minor folds (Pedrera et al., 2007;Pedrera et al., 2010a).To the east, these minor folds progressively change their trend from ENE-WSW to WNW-ESE (Pedrera et al., 2010a).In addition, the late Miocene sediments are quite deformed by several sets of faults.The most abundant set is formed by WNW-ESE to NW-SE normal faults that show a wi- stream.In addition, the role of the above-described active folds in the landscape evolution and drainage development was characterized in the folded eastern Almanzora corridor and western Huércal-Overa basin (Pedrera et al., 2009c).

7KH $OSXMDUUDQ FRUULGRU WKH 7DEHUQDV EDVLQ DQG the Sorbas-Vera basin
The Alpujarran corridor is an E-W elongated valley formed by a roughly synformal structure located between the Sierra Nevada to the north and the Sierras Lújar-Contraviesa-Gádor to the south.Eastwards the corridor extends to the Tabernas basin, which continues into the Sorbas-Vera basin, between Sierra de Los Filabres to the north and Sierra Alhamilla and Sierra Cabrera to the VRXWK )LJV DQG 7KHVH EDVLQV DUH SDUWLDOO\ ¿OOHG with lower Miocene to Quaternary deposits and constitute a zone of crustal weakness where recent and active deformation structures are nucleated (Ott d'Estevou et al., 1990;Rodríguez-Fernández, 1982).Researchers agree on the presence throughout this area of a main right-lateral fault zone (e.g., Sanz de Galdeano et al., 1985;Galindo-Zaldívar, 1986;Sanz de Galdeano, 1989;Jabaloy et al., 1992;Galindo-Zaldívar et al., 2003;Martínez-Díaz and Hernández-Enrile, 2004;Martínez-Martínez, 2006;Martínez-Martínez et al., 2006;Sanz de Galdeano et al., 2010).However, controversy persists concerning the deep continuity of the structures, the relationships of the exposes faults with seismicity, the driving mechanisms, and in some cases the age of fault activity.On the other hand, there is a general consensus regarding the features of the major left-lateral Palomares fault zone (PFZ), which developed since the late Tortonian in the eastern part of the Sorbas-Vera basin (e.g., Bousquet and Phillip, 1976;Bousquet, 1979;Montenat et al., 1987;Weijermars, 1987;Ott d'Estevou et al., 1990;Silva et al., 1993;Booth-Rea et al., 2003).

Miocene tectonic structures
After the end of metamorphism in the Internal Zones, a set of top-to-the west low-angle normal faults thinned the crust and exhumed the Nevado-Filábride complex, up to the middle Miocene (e.g., Aldaya et al., 1984;Galindo Zaldívar, 1986;García-Dueñas and Martínez-Martínez, 1988;Jabaloy et al., 1993).Afterwards, the crustal-thinning process shifted to crustal thickening and relief formation, when the Sierra Nevada and Sierra de los Filabres started to emerge (Braga et al., 2003) as large antiforms that folded the extensional detachments that generates a steep scarp.The fault surface shows horizontal striation with a left-lateral sense of motion overprinted on the normal striation.The eastern Almanzora corridor (Somontín-Partaloa sector) and the western Huércal-Overa basin are both deformed by widespread small-scale contractional tectonic structures, which include WNW-ESE trending dextral faults and ENE-WSW oriented open folds, fault-propagation folds, and reverse faults (Figs. 2 and 3A;Briend et al., 1990;Pedrera et al., 2009a and2009b).Using a geomorphological approach, García-Meléndez (2000) and García-Meléndez et al.
(2004 GH¿QHG WKH $OER[ IDXOW DV DQ (1(:6: WR (: fault zone with reverse-dextral kinematics that runs from the eastern Huércal-Overa basin as far as the Almanzora corridor to the west.The La Molata fault-propagation fold is one of the best-exposed outcrops (Fig. 2, Pedrera et al., 2009a.This fold and its related faults have propagated progressively, as evidenced by the syn-tectonic geometry of the growth strata.Strain rates calculated across the structure give a constant ~0.007 mm/yr horizontal shortening and ~0.014 mm/yr vertical displacement from the mid-Pleistocene to the present (Pedrera et al., 2009a).The central and eastern part of the Huércal-Overa basin is deformed by ENE-WSW trending reverse faults with a splay geometry, belonging to the southern end of the Alhama de Murcia left-lateral transcurrent fault (AMF) (Martínez-Díaz et al., this volume).These faults deform the Quaternary alluvial fan deposits in the eastern Huércal-Overa basin (Groupe de Recherche Néotectonique, 1977;Briend, 1981) and have been recently characterized with geomorphological, structural, and paleoseismologic studies (García-Meléndez et al., 2003;Soler et al., 2003;Masana et al., 2005;Meijninger and Vissers, 2006;Ortuño et al., 2009).Thus, paleoseismologic studies near Goñar (Fig. 2) in the eastern Huércal-Overa basin, identify at least two paleoearthquakes associated with the AMF during the last 150 ka and estimate a minimum vertical slip rate of ~0.02 mm/yr in the southern fault termination since the Middle Pleistocene (Ortuño et al., 2009).In addition, a palaeoseismologic study in El Ruchete sec-WRU )LJ LGHQWL¿HG IDXOW VHJPHQWV ZLWK VKRUWWHUP VOLS rates ranging from 0.01 to 0.4 mm/yr and two possible paleoearthquakes deposits associated with them (Masana et al., 2005).This reverse fault segment probably belongs to the horsetail reverse splay of the AMF (Fig. 2).
The E-W right-lateral faults along the Alpujarras, the E-W oriented right-lateral faults of the southern Tabernas basin, and the dextral-reverse faults in the southern Sorbas basin have been traditionally interpreted as transpressive faults developed under N/S to NNW/SSE compression (e.g., Sanz de Galdeano et al., 1985Galdeano et al., , 1989;;Stapel, 1996;Huibregtse et al., 1998;Jonk and Bierman, 2002).However, Martínez-Martínez (2006) and Martínez- Martínez et al. (2006) propose a different interpretation for the Alpujarra right-lateral faults.They consider this fault zone to be part of a WSW-directed extensional system connecting two normal fault systems that thinned the Betic hinterland since the middle Miocene to the present.
In the absence of accurate, deep geophysical data, the deep continuity of the right-lateral faults has been considered to have a crustal (Sanz de Galdeano et al., 1985) or at least shallow crustal character (Martínez-Díaz and Hernández-Enrile, 2004;Martínez-Martínez et al., 2006), although Galindo-Zaldívar (1986) suggests that fault structures of the central Alpujarras corridor are restricted to the shallowest part of the crust.
Toward the east, the Palomares fault zone (PFZ), which is formed by several N10ºE to N20ºE left-lateral fault segments, deforms the eastern sector of the Vera basin (Fig. 4C) (Bousquet and Phillip, 1976;Bousquet, 1979;Weijermars, 1987).The Miocene sediments of the Vera basin are involved within the fault zone.Therefore, two GHSRFHQWHUV ¿OOHG E\ ODWHVW 7RUWRQLDQ WR 4XDWHUQDU\ VHGLments are linked to the movement of Arteal and Palomares fault segments (Fig. 4C; Booth-Rea et al., 2003).Thus, the PFZ is considered a transcurrent deformation zone    Montenat et al., 1987;Ott d'Estevou et al. 1990;Silva et al., 1993;Ruano et al., 2007).Both ends are characterized by a change in the fault segments direction, which acquire a splay geometry that may be consistent with the development of reverse faults and antiforms since upper Miocene (Sierra Cabrera and Sierra Almagrera).
A clear evidence of Quaternary faulting is found in the eastern Alpujarran corridor, in the Laujar de Andarax zone (García-Tortosa and Sanz de Galdeano, 2007).This consists of an E-W trending fault zone formed by southward-dipping normal faults segments affecting Quaternary deposits (Fig. 3B and 4A).Quaternary faults with related seismic activity are also found along a NW-SE zone that stretches from Almería to the Tabernas basin and separates Sierra Alhamilla from Sierra de Gádor (Sanz de Galdeano et al., 2010).Seismicity is concentrated in the basement at the north-western edge, near Gergal, and this may correspond to the area of propagation of the fault zone.
The PFZ deforms Pleistocene conglomerates, close to Palomares village, developing an impressive fault-mirror with subhorizontal striations (Bousquet and Phillip, 1976).Pliocene-Quaternary sedimentary depocenters reveal that deformation along the PFZ fault zone migrated towards the eastern Arteal fault segment, which bounds the western mountain front of Sierra Almagrera (Booth-Rea et al., 2003).In addition, the Quaternary activity of the PFZ favoured stream dissection, headward erosion of streams transverse to the active fault segments, and the asymmetry of the drainage network (Booth-Rea et al., 2004;Stokes, 2008).The almost straight coastline from Palomares to Punta del Peñón is controlled by the PFZ (Figs. 3C and 4C), therefore the Late Pleistocene-Holocene marine terraces are uplifted along the coast (Goy and Zazo, 1986).In addition, Pleistocene conglomerates located in the Punta del Peñón contain numerous pebbles striated under the left-lateral shear of the PFZ.At its southern end, the PFZ splays into a horsetail formed by ENE-WSW reverse faults (Fig. 3C and 4C).Southdipping reverse faults form the north boundary of the Sierra Cabrera (Booth-Rea et al., 2004), locally affecting Quaternary sediments (Sanz de Galdeano, 1987), and north-dipping reverse faults constitute the southern edge of the Sierra (Keller et al., 1995).The CuaTeNeo (Cuanti-¿FLDFLyQ GH OD 7HFWyQLFD DFWXDO \ 1HRWHFWyQLFD *36 QRQ permanent network was installed in 1996 to quantify the deformation in the Eastern Betic Cordillera.The network consists of 15 monuments covering an area of 120x50 km in Murcia and Almería (Colomina et al., 1998;Khazaradze et al., 2007 and2008).In the northern part of the GPS network, the stations placed westward of the AMF DQG WKH 3)= VKRZ LQVLJQL¿FDQW PRWLRQV ZLWK UHVSHFW WR the stable part of the Eurasian plate.The GPS sites placed close to coast, eastward of the AMF and the PFZ, move 1-1.5 mm/yr toward the NNW revealing a strain accumulation (Echeverria et al., 2011;Frontera et al., 2011).

The Campo de Dalías and the Almería-Níjar basin
The Campo de Dalías and the Almería-Níjar basin are located at the boundary between the Alborán Sea and the Betic Cordillera.In both basins, the Tortonian and Pliocene marine sedimentary rocks, which belonged to the Northern Alborán basin, have emerged in Quaternary times (Fig. 5).

Late Miocene tectonic structures
The Carboneras fault zone (CFZ) is a major regional left-lateral fault that extends onshore along the Almería-Níjar basin (Bousquet and Montenant 1974;Ott d'Estevou and Montenant;1985, Keller et al., 1995;;Scotney et al., 2000;Faulkner et al., 2003) and continues offshore along the Almería Gulf in a NE-SW direction (Fig. 5; De Larouzière et al., 1988;Gràcia et al., 2006.The upper Miocene sediments, together with metamorphic and volcanic basement rocks, crop out along the highly deformed CFZ (Bousquet and Montenant 1974;Rutter et al., 1986;Van de Poel, 1991;Keller et al., 1995).The nucleation of the crustal-scale CFZ is closely linked to the Miocene YROFDQLVP ZKLFK PRGL¿HG WKH WKHUPDO VWUXFWXUH DQG WKH strength of the lithosphere (Pedrera et al., 2010b).Northwards of the CFZ, the sedimentary rocks are widely deformed by folds with a hundreds of meters amplitude and consistently showing an ENE-WSW strike onshore and offshore (Figs.4B and 5).These folds deformed the sediments before the Messinian generating a cartographic unconformity between the highly folded upper Tortonian rocks and the less deformed post-Messinian sediments (Weijermars et al., 1985).
To the north, the highest reliefs in the area are linked to culminations on the hinge line of the Sierra Alhamilla and Sierra the Gádor antiforms, which have an ENE-WSW orientation, 10 km of maximum amplitude, and are 25 to 30 km long respectively, and more than 1300 m high.The lower Tortonian-Serravallian conglomerates and the upper Tortonian sediments that surround the ranges are folded, revealing the fold geometry and the age of the deformation.In the Sierra Alhamilla, the late Tortonian rocks dip 20º in the southern slopes, yet are vertical or even overturned on the northern slopes as a consequence of the northward fold vergence and the activity of the E-W oriented high-angle reverse to right-lateral Lucainena fault zone (Weijermars et al., 1985;Sanz de Galdeano, 1989).
The Níjar basin is intensely deformed by high-angle dipping normal faults since the Late Miocene (Martínez-Díaz and Hernández-Enrile, 2004;Marín-Lechado et al., 2005;Pedrera et al., 2006;Sanz de Galdeano et al., 2010).They have a consistent NNW-SSE to NW-SE strike.Although the normal faults have a widespread distribution, their presence predominates in western Níjar, extending toward the Tabernas basins and very locally toward the Sorbas basin.The Níjar basin depocenter is associated with this NW-SE oriented normal fault activity.The maximum sedimentary thickness, established from gravity data, reaches more than 1 km in the western sector of the basin (Pedrera et al., 2006).The fault surfaces dip towards the SW and usually deform the Tortonian and Messinian sediments, showing variable geometries from listric to domino-like systems.To the south-eastern part of the Almería Níjar basin, NW-SE normal faults dipping mainly to the NE deform the Pliocene sediments, sometimes showing syn-sedimentary features (Marín-Lechado et al., 2005;Pedrera et al., 2006).

Active tectonic structures
ENE-WSW open to gentle N-vergent folds affect the Pliocene and Quaternary sediments that extend along the continental shelf of the Almería Gulf, the Campo de Barranquete (Pedrera et al., 2012).Fault slip enhances toward the linkage sectors with an estimated long-term slip rate of 0.07±0.03mm/yrsince the Pleistocene (Fig. 5; Pedrera et al., 2012).The normal to normal-oblique faults continue toward the Alborán Sea, as deduced from NW-SE trending lineaments detected by bathymetric studies (Fig. 5; Gràcia et al., 2006).
A non-permanent GPS network was installed in the Campo de Dalías to control the crustal deformation associated with active folds and faults.GPS measurements were made in 2006 and 2011, and the data are being proc-HVVHG ,Q DGGLWLRQ WZR SUHFLVLRQ OHYHOOLQJ SUR¿OHV ZHUH installed along the southern part of the Balanegra fault zone and measured in 2006, 2007, 2009, and 2010 to estimate the short-term fault-slip rate (Marín-Lechado et al., 2010).

Seismicity and Earthquake Sources
The sector of the Betic Cordillera addressed in this paper is affected by distributed seismicity of low to moderate magnitude, which is limited to the upper crust (e.g., Stich et al., 2003Stich et al., , 2010;;Fernández-Ibáñez and Soto, 2008).Earthquakes larger than Mw 5 rarely occur (Table 1).These major earthquakes can cautiously be associated with possible source faults, on the basis of damage descriptions in the cases of pre-instrumentally registered events and the estimated location and source analysis derived from the moment tensor solution in the case of the most recent earthquakes (Table 1).In the Campo de Dalías and surrounding sectors, large events occurred close to the village of Dalías (August 25, 1804, with felt intensity VIII-IX in the scale EMS-98 used throughout this paper, and Mw 6.4 macroseismic magnitude) and close to Adra, where a Mw 6.1 earthquake and Mw 5.5 aftershock occurred on June 16, 1910.The source parameters of the main Adra shock was established after analysing six analogue seismogram recordings (M 0 =1.50•10 -18 Nm, Mw=6.1, oblique strike-slip event at 16 km in depth; Stich et al., 2003).Recently, two related events occurred to the south of Berja (December 23, 1993, Mw 5.3, m bLg ), and of Guardias Viejas (January 4, 1994, Mw 4.9).Both reveal strike-slip, slightly oblique fault plane solutions with a N120ºE oriented dextral nodal plane (Stich et al., 2001), very similar to that found for the June 16, 1910 Adra earthquake.Stich et al. (2001) analysed the complete 1993-1994 seismic series and later seismicity in the area up to 1998, recognizing 39 multiplet clusters with N120-130ºE and N60-70ºE lineaments.These earthquakes could be assigned to the Balanegra fault zone (Marín-Lechado et al., 2005), which is formed by N120ºE Dalías (Marín-Lechado et al., 2006) and the Níjar basin (Fig. 5; Sanz de Galdeano, 1989;Huibregtse et al., 1998;Pedrera et al., 2006).These folds indicate the continuity of the contractional deformation after the major Messinian unconformity.In addition, normal to normal-oblique faults deform alluvial sediments up to the Pliocene and the Quaternary, generating fault scarps.In the Almería-Níjar basin, NNW-SSE to NW-SE normal faults are responsible for high slopes and sharp topography in the western part of the Sierra Alhamilla antiform and deform its southern limb.Therefore, from Gergal to Cabo de Gata, they control the Andarax valley geometry and the rectilinear coast line (e.g., Martínez-Díaz and Hernández-Enrile, 2004;Marín-Lechado et al., 2005;Pedrera et al., 2006;Sanz de Galdeano et al., 2010).From a geomorphological point of view, abrupt changes in the channels slope are probably associated to the activity of these normal faults (Giaconia, 2012).
Onshore recent tectonic activity of the CFZ is well observed near Barranquete, in the SW sector, where N30º-45ºE subvertical left-lateral fault surfaces deform Quaternary sediments (e.g., Boorsma, 1992;Pedrera et al., 2006).There, detailed geochronological and paleoseismic studies have been carried out (Moreno, 2011).Slip-rates, paleoseismologic, and seismic potential behaviour of the CFZ derived from onshore-offshore results have been recently described in detail by Moreno (2011) .A GPS station on the southern fault block is moving 1.5±0.7 mm/ yr toward the NNE with respect to northward stations.This can be interpreted as being mainly caused by the left-lateral strike slip motion along the CFZ (Khazaradze et al., 2010).
to N160ºE trending oblique-slip segments.Instrumental seismicity is concentrated in the basement at the northwestern end of the fault zone, where the 2002 Gergal earthquake Mw 4.7 was located (Sanz de Galdeano et al., 2010).In addition, the 1894 Nacimiento earthquake (VII) could be tentatively associated with these normal faults.The 1522 Almería earthquake (VIII-IX), for which the exact epicentre is unknown, has been associated with the offshore segment of the CFZ (Reicherter and Hübscher, 2006).Vera was destroyed in 1518 (VIII-IX) by an earth-Vera was destroyed in 1518 (VIII-IX) by an earth-VIII-IX) by an earth-IX) by an earth-earthquake that could be hosted by the left-lateral Palomares fault (Bousquet, 1979;Weijermars, 1987).Toward the north, two moderate earthquakes were registered in the Almanzora corridor: the April 5, 1932 Lúcar earthquake (VIII, m D 4.8) and the April 16, 1972 NW Partaloa earthquake (VII, m bLg 4.8).The Lúcar earthquake could tentatively be associated with the Lúcar and Somontín fault zone, which extends from the Almanzora basin towards the Sierra de la Estancias, crossing the village of Lúcar.The village of Partaloa is located above a sector deformed by active ENE-WSW reverse faults and associated folds (Pedrera et al., 2007(Pedrera et al., , 2009a(Pedrera et al., , 2009c)).

Discussion and Conclusions
This work compiles the available information on the late Miocene to Quaternary faults and folds in the centraleastern Internal Zones of the Betic Cordillera.Some of these features have probably been the source of moderate-sized earthquakes throughout history and therefore are potential sources of future earthquakes.

Late Miocene geodynamic evolution
Regarding the evolution of the tectonic structures over time, folding started in the present position of the Sierra Nevada and Sierra de Los Filabres during the Serravallian-early Tortonian (Fig. 6).Therefore, stratigraphic and sedimentological studies indicate that a large E-W island started to emerge there at this time (Braga et al., 2003).These large-scale antiforms underwent progressive lateral growth from east to west, folding the previous H[WHQVLRQDO GHWDFKPHQWV DQG WKHUHIRUH IDYRXULQJ WKH ¿QDO exhumation of the Nevado-Filábride rocks.Fission-track analyses revealed that cooling to nearly surface tempera-WXUHV RFFXUUHG ¿UVW LQ WKH 6LHUUD GH /RV )LODEUHV GXULQJ the mid-Serravallian (12 Ma) and later in Sierra Nevada, located to the west (9-8 Ma; Johnson et al. 1997).The erosion of these ranges supplied sediments to the nearby basins.Progressive unconformities found in the Serravallian-lower Tortonian conglomerate formation located in the Almanzora corridor are coeval with the Sierra de Los Filabres antiform growth.Since the late Tortonian, folding continues and propagates northwards (Sierra de Las Estancias) and southwards (the Sierra de Gádor, the Sierra Alhamilla and the Sierra Cabrera).In addition, the Almanzora corridor, the Huércal-Overa basin, the Al-pujarran corridor, and the Tabernas basin acquired their elongate shape.

Carboneras
Coevally to large-scale open fold development, E-W transpressive right-lateral and reverse faults nucleated along the Alpujarra, the Tabernas, and the Sorbas basins while the NNE-SSW/NE-SW left-lateral Palomares and Carboneras fault zones occurred in the easternmost part of the cordillera (Fig. 6).Thus, the Polopos fault has been interpreted as a conjugate fault system to the Carboneras and Palomares left-lateral fault zones (Giaconia et al., 2012).Coeval to the relief growth, NW-SE to E-W normal and oblique slip normal faults developed.
During the Messinian, Pliocene and Quaternary, compression contributed to the progression of the moderate crustal thickening and to the regional progressive emer-VLRQ RI WKH PDULQH EDVLQV ZLWK WKH ¿QDO FDSWXUH E\ WKH drainage network of the endorheic basins.Active folds caused the emersion of the northern Alborán Sea (Marín-Lechado et al., 2006).In addition, there was continued activity of some segments of the strike-slip faults.Moreover, normal and normal-oblique faults have remained active during the Quaternary to the present in this part of the cordillera.

Active Tectonics
The present study summarized the most prominent active faults of the central-eastern Internal Zones of the Betic Cordillera (from 3.1ºW to 1.7ºW and to the south of 37.525ºN) providing detailed maps of the fault and fold traces (Fig. 7).The Campo de Dalías and surrounding sectors are probably the sites with the greatest concentra- tion of large earthquakes during the recent history.Moderate-sized earthquakes (Mw 5.0 to 6.0-6.5)have occurred in this area at fairly regular intervals, in 1804, 1910, and 1993 probably associated to the Balanegra fault zone activity (Marín-Lechado et al., 2010).Despite the absence of clear historic earthquakes associated with the Loma del Viento fault, it is reasonable to consider it as a potential seismic fault (Pedrera et al., 2012).There, we have designed a multidisciplinary control of the potential earthquakes sources.We have mapped the active faults and folds in detail.In addition, we performed a 3D geological model by incorporating borehole and geophysical data to establish the geometry of the tectonic structures.The sector is monitored with a non-permanent GPS network and KLJKSUHFLVLRQ OHYHOOLQJ SUR¿OHV )LJ 7KH JHRPHWULF knowledge of these structures combined with geodetic measurements of tectonic-strain accumulation yield improved models of nucleation, linkage, and propagation of active faults, as well as their seismic implications.
The NW-SE trending Quaternary faults extending from Almería to the Tabernas basin and separating Sierra Alhamilla from Sierra de Gádor have related seismicity (Fig. 7).These NW-SE normal faults have higher seismic potential than does the E-W dextral system (the 2002, Mw 4.7 Gergal earthquake and the 1894 Nacimiento earthquake, VII).
Toward the north in the Almanzora corridor, the Lúcar-Somontín NW-SE to WNW-ESE trending Quaternary faults could also cautiously be considered as possible sources of moderate-magnitude seismicity (the April 5, 1932 Lúcar m D 4.8 earthquake, VIII).Toward the east, between Albox and Partaloa, several small reverse faults and associated compressive structures deforming Qua-WHUQDU\ DOOXYLDO DQG ÀXYLDO VHGLPHQWV )LJ KDYH EHHQ GHVFULEHG" 7KH V\QIROGLQJ IDQ JHRPHWU\ REVHUYHG LQ the one of these structures (La Molata structure, Pedrera et al., 2009a) suggests a slow and progressive deformation from middle Pleistocene onward.They do not show scarps or erosive deposits, such as clastic wedges, indicative of abrupt deformation events related to earthquakes, suggesting that the La Molata structure is most likely connected with aseismic slip during Quaternary faultrelated fold growth.Nevertheless, some of these reverse fault segments could have associated moderate-sized events such as the April 16, 1972 NW Partaloa, m bLg 4.8 earthquake (VII).Regarding the proximity between the villages Lúcar and Partaloa, further seismic studies of the main shock parameters are necessary to identify viable source structures.
The PFZ is very favourably oriented (N10-20ºE trend) ZLWK UHVSHFW WR WKH SUHVHQWGD\ VWUHVV ¿HOG IRU OHIWODWHUDO strike-slip displacement.The angle between the fault strike and the maximum principal stress is around 30º.Therefore, this fault probably nucleates moderate-sized earthquakes (1518 Vera earthquake).Unlike the Palomares fault, the CFZ is almost orthogonal to the presentday maximum horizontal compressive stress.Although not very suitably oriented to act as a strike-slip fault, it could act as a high-angle reverse or reverse-oblique fault despite its sub-vertical geometry.Paleoseismic data, high UHVROXWLRQ VHLVPLF SUR¿OHV DQG VHGLPHQW FRULQJ LQGLFDWH Quaternary activity of some fault segments (Reicherter and Hübscher, 2006;Moreno et al., 2009).The ongoing GPS results derived from the CuaTeNeo network will decisively contribute to understand the relationship between the strain accumulation and seismic potential of the Carboneras and Palomares fault zones (Fig. 7).

Fig
Fig. 3.-Field view of several active tectonic structures placed in the central-eastern Betic Cordillera.(A) ENE-WSW trending reverse fault and associated antiform that deform Quaternary conglomerates near Albox in the Huércal-Overa basin.(B) Laujar de Andarax normal fault: E-W oriented normal fault dipping toward the south affecting Quaternary sedimentary rocksin the northern Alpujarran corridor margin.(C) Rectilinear coast line that coincides with a fault segment of the left-lateral Palomares fault zone, which controls the eastern termination of the Sierra Cabrera.(D) Balanegra fault zone: NW-SE oriented normal fault segment that deforms Quaternary sediments in the western termination of the Sierra de Gádor, close to the village of Berja.Fig. 3.-Ejemplos de algunas estructuras activas situadas en el área de estudio.(A) Falla inversa y pliegue asociado de direcciones ENE-OSO que deforman conglomerados cuaternarios en las proximidades de Albox, en la Cuenca de Huércal-Overa.(B) Falla normal de Laujar de Andarax: segmento que afecta a sedimentos cuaternarios con dirección aproximada E-O y buzamiento hacia el Sur.(C) Tramo de costa rectilíneo asociado a un segmento de la Falla de Palomares que controla la terminación oriental de Sierra Cabrera.(D) Zona de falla de Balanegra: segmento de dirección NO-SE que deforma sedimentos cuaternarios en la terminación occidental de la Sierra de Gador, cerca de Berja.