The eastern Betic Cordillera, Spain, is the most seismically active area within the Iberian Peninsula. We present a Global Positioning System (GPS)-derived horizontal crustal deformation derived from five occupations of the CuaTeNeo GPS network (1997, 2002, 2006, 2009 and 2011) that clearly shows continuing tectonic activity in the SE Betics. The most prominent feature of the GPS velocity field is the NW oriented motion of the majority of the stations at rates ranging from 2 mm/yr near the coast to 0.5 mm/yr inland. This type of deformation indicates that the main driving force responsible for the observed velocities is related to the on-going convergence between Nubia and Eurasia plates. The calculated deformation field shows evidence for localized deformation related to active faults within the area. Most of the deformation is concentrated on the Alhama de Murcia fault, the source of the 2011 Lorca earthquake (Mw 5.2). We estimate a reverse-sinistral geodetic slip rate of 1.5±0.3 mm/yr for this fault. Our crustal deformation field and analyses are important contributions to estimating seismic hazard for the eastern Betics, since it is the first time crustal deformation rates at this scale are presented.

Three-dimensional paleoseismology in strike-slip faults with slip rates less than 1 mm per year involves a great methodological challenge. We adapted 3D trenching to track buried channels offset by the Alhama de Murcia seismogenic left-lateral strike-slip fault (SE Iberia). A fault net slip of 0.9 ± 0.1 mm/yr was determined using statistical analysis of piercing lines for one buried channel, whose age is constrained between 15.2 ± 1.1 ka and 21.9-22.3 cal BP. This value is larger and more accurate than the previously published slip rates for this fault. The minimum number of five paleo-earthquakes identified since the deposition of dated layers suggests a maximum average recurrence interval of approximately 5 ka. The combination of both seismic parameters yields a maximum slip per event between 5.3 and 6.3 m. We show that accurately planned trenching strategies and data processing may be key to obtaining robust paleoseismic parameters in low seismicity areas.

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SUMMARY The Pyrenees mountain belt, which separates the Iberian Peninsula from the rest of the European continent, is part of the Alpine–Himalayan orogenic belt, formed as a result of a collision between the African and Eurasian Plates. Although the instrumental seismicity in the Pyrenees is moderate, in the past centuries a number of destructive earthquakes have occurred, which could indicate continuing tectonic activity of the area. We analyse GPS observations spanning 3.5 yr from 35 continuous stations in the Pyrenees region and find significant on‐going extension perpendicular to the range at 2.5 ± 0.5 nstrain yr–1, with the possibility of higher strain rates concentrated in the westernmost part of the range. This finding is in agreement with the predominantly normal faulting focal mechanisms of earthquakes that occur in the area and suggests a recurrence time for magnitude 6.5 earthquakes of 2200–2500 yr.

To define the seismic potential of the left-lateral strike-slip Alhama de Murcia fault (SE Iberian Peninsula), we calculated its slip rate by measuring offset linear features of known age using a morphotectonic analysis. The Lorca-Totana section of the fault yielded a minimum slip rate of 1.0 ± 0.2 mm/a for the past 30 ka, based on a channel whose age is estimated by OSL technique. The minimum left-lateral slip rate of the Goñar-Lorca section is 1.6-1.7 mm/a for the past 200 ka, based on eight offset surface channels, previously mapped alluvial fans dated by TL, and by new U-series dating of pedogenic carbonate. The U-series technique was used here for first time in the Iberian Peninsula to date small amounts (mg) of pedogenic carbonate. According to the newly estimated slip rate values, the Alhama de Murcia fault is one of the most active faults in the Eastern Betics Shear Zone. These values are larger and have fewer uncertainties in 1 comparison with previous slip rates estimations. In the Lorca-Totana section, the new lateral slip rate is compared with a slip rate calculated by means of a paleoseismic study showing good agreement between the values obtained with the two approaches.We encourage the combination of paleoseismology and morphotectonic analysis to obtain reliable slip rates for faults with scarce evidence of late Holocene slip.