Geodetic evidence for continuing tectonic activity of the Carboneras fault (SE Spain)

The Carboneras fault zone (CFZ) is a prominent onshore offshore strike slip fault that forms part of the Eastern Betic Shear Zone (EBSZ), located in SE Spain. In this work, we show for the first time, the continuing tectonic ac- tivity of the CFZ and quantify its geodetic slip-rates using continuous and campaign GPS observations conducted during the last decade. We find that the left-lateral motion dominates the kinematics of the CFZ, with a strike slip rate of 1.3 ± 0.2 mm/yr along the N48° direction. The shortening component is significantly lower and poorly constrained. Recent onshore and offshore paleoseismic and geomorphic results across the CFZ suggest a mini- mum Late Pleistocene to present-day strike slip rate of 1.1 mm/yr. Considering the similarity of the geologic and geodetic slip rates measured at different points along the fault, the northern segment of the CFZ must have been slipping approximately at a constant rate during the Quaternary. Regarding the eastern Alpujarras fault zone corridor (AFZ), located to the north of the CFZ, our GPS measurements corroborate that this zone is ac- tive and exhibits a right-lateral motion. These opposite type strike slip motion across the AFZ and CFZ is a result of a push-type force due to Nubia and Eurasia plate convergence, which, in turn, causes the westward escape of the block bounded by these two fault zones

Deformación cortical mediante GPS en el Este de la Cordillera Bética. Especial énfasis en el terremoto de Lorca.

Resumen: En este trabajo se presenta el campo de deformación cortical en el Este de la Cordillera Bética, basado en observaciones de la red GPS CuaTeNeo. Esta red geodésica no permanente, se estableció en 1996 con el objetivo de cuantificar las deformaciones tectónicas actuales del SE de las Béticas. La red está formada por 15 monumentos estables distribuidos entre Murcia y Almería y ha sido observada en cinco ocasiones (1997, 2002, 2006, 2009 y 2011). Los resultados obtenidos muestran en general un campo de velocidades no superior a los 2 mm/a y con una dirección similar a la convergencia entre las placas Eurasiática y Nubia. Las estaciones situadas en el interior presentan velocidades de menor magnitud. El campo de deformación cortical obtenido muestra que de las fallas de la Zona de Cizalla de las Béticas Orientales permanecen activas. El mecanismo focal del terremoto de Mw5.1 ocurrido en Lorca el 11/05/2011, atribuido a la Falla Alhama de Murcia, muestra una componente inversa y de desgarre, de acuerdo con la deformación cortical detectada a través de las observaciones de GPS. Ha sido posible detectar un salto co-sísmico debido al terremoto en la estación continua LORC de ~5mm hacia el Norte. Palabras clave: GPS, terremotos, neotectónica, Béticas. Abstract: In this communication is presented the updated crustal deformation field in the Eastern Betics, based on GPS observations of the CuaTeNeo network. This non-permanent network was established in 1996 to quantify the current tectonic deformation of the SE Betics. The network consist of 15 stable monuments distributed between Murcia and Almeria and were observed five times (1997, 2002, 2006, 2009 and 2011). In general, the results show a velocity field lower than 2 mm/yr with a similar trend to the Eurasia and Nubia plate convergence. Stations located to the inland exhibit lower velocity vector. The crustal deformation field shows evidences of active faults of the Eastern Betic Shear Zone. The focal mechanism calculated for the May 11th 2011 earthquake in Lorca, attributed to the Alhama de Murcia Fault, shows reverse and sinistral components, in accordance to the crustal deformation detected by GPS. Co-seismic offset of ~5mm to the North was detected due to the earthquake in the continuous GPS LORC station. Key words: GPS, earthquakes, neotectonics, Betics

GPS studies of active deformation in the Pyrenees

The Pyrenees mountain belt, which separates the Iberian Peninsula from the rest of the European continent, is part of the AlpineHimalayan 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 yr1, 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 22002500 yr

Crustal deformation in eastern Betics from CuaTeNeo GPS network

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 obtained 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

DInSAR coseismic deformation of the May 2011 Mw 5.1 Lorca earthquake, (Southern Spain)

The coseismic superficial deformation at the region of Lorca (Murcia, southeastern Spain) due to the Mw 5.1 earthquake on 11 May 2011 was characterized by a multidisciplinary team, integrating information from DInSAR, GPS and numerical modelling techniques. Despite the moderate magnitude of the event, quantitative information was obtained from the interferometric study of a pair of TerraSAR-X images. The DinSAR results defined the trace of the fault plane and evidenced uplift of the hanging wall block in agreement with the estimated deformation obtained through an elastic rupture dislocation numerical model. Meanwhile for the footwall block, interferometric results showed that tectonic deformation is masked by an important subsidence related to groundwater extraction previously identified at the area of study. Horizontal crustal deformation rates and velocity vectors,obtained from GPS stations existent at the area, were also coherent with the tectonic setting of the southern margin of the Iberian Peninsula and with the focal mechanism calculated or the Lorca event. The analysis of a continuous GPS site in Lorca showed good agreement with the horizontal NS direction component relative to the numerical model and tectonics of the region. This is the first time at this seismic active area that a multitechnique analysis has been performed immediately after the occurrence of a seismic event, comparing the existing deformation data with a theoretical numerical model based on estimated seismic rupture dislocation

Minerales supergénicos de Hg de Almadén: Una forma natural de fijar mercurio

Como es conocido, la zona de Almadén constituye uno de los reservorios de mercurio más importantes del mundo (Higueras et al., 2006)

Topo-Iberia Project: CGPS crustal velocity field in the Iberian Peninsula and Morocco

A new continuous GPS network was installed under the umbrella of a research project called 'Geociencias en Iberia: Estudios integrados de topografı´a y evolución 4D (Topo-Iberia)', to improve understanding of kinematic behavior of the Iberian Peninsula region. Here we present a velocity field based on the analysis of the 4 years of data from 25 stations constituting the network, which were analyzed by three different analysis groups contributing to the project. Different geodetic software packages (GIPSY-OASIS, Bernese and GAMIT) as well as different approaches were used to estimate rates of present day crustal deformation in the Iberian Peninsula and Morocco. In order to ensure the consistency of the velocity fields determined by the three groups, the velocities obtained by each analysis center were transformed into a common Eurasia Reference Frame. After that, the strain rate field was calculated. The results put in evidence more prominent residual motions in Morocco and southernmost part of the Iberian Peninsula. In particular, the dilatation and shear strain rates reach their maximum values in the Central Betics and northern Alboran Sea. A small region of high shear strain rate is observed in the east-central part of the peninsula and another deformation focus is located around the Strait of Gibraltar and the Gulf of Cadiz

Goodbye Hartmann trial: a prospective, international, multicenter, observational study on the current use of a surgical procedure developed a century ago

Background: Literature suggests colonic resection and primary anastomosis (RPA) instead of Hartmann's procedure (HP) for the treatment of left-sided colonic emergencies. We aim to evaluate the surgical options globally used to treat patients with acute left-sided colonic emergencies and the factors that leading to the choice of treatment, comparing HP and RPA. Methods: This is a prospective, international, multicenter, observational study registered on ClinicalTrials.gov. A total 1215 patients with left-sided colonic emergencies who required surgery were included from 204 centers during the period of March 1, 2020, to May 31, 2020. with a 1-year follow-up. Results: 564 patients (43.1%) were females. The mean age was 65.9 ± 15.6 years. HP was performed in 697 (57.3%) patients and RPA in 384 (31.6%) cases. Complicated acute diverticulitis was the most common cause of left-sided colonic emergencies (40.2%), followed by colorectal malignancy (36.6%). Severe complications (Clavien-Dindo ≥ 3b) were higher in the HP group (P < 0.001). 30-day mortality was higher in HP patients (13.7%), especially in case of bowel perforation and diffused peritonitis. 1-year follow-up showed no differences on ostomy reversal rate between HP and RPA. (P = 0.127). A backward likelihood logistic regression model showed that RPA was preferred in younger patients, having low ASA score (≤ 3), in case of large bowel obstruction, absence of colonic ischemia, longer time from admission to surgery, operating early at the day working hours, by a surgeon who performed more than 50 colorectal resections. Conclusions: After 100 years since the first Hartmann's procedure, HP remains the most common treatment for left-sided colorectal emergencies. Treatment's choice depends on patient characteristics, the time of surgery and the experience of the surgeon. RPA should be considered as the gold standard for surgery, with HP being an exception

GPS present-day kinematics of the eastern Betics, Spain

[cat] La serralada de les Bètiques orientals, al sud-est d'Espanya, és una de les àrees sísmicament més actives de la península ibèrica. El sistema de Cisalla de les Bètiques orientals (EBSZ) absorbeix part de la convergència entre les plaques Eurasiàtiques i Africana (Nubia). L'EBSZ és un sistema de falles transpressives senestres format per diverses falles, que de sud a nord són: Carboneras, Palomares, Alhama de Murcia, Carrascoy i Bajo-Segura. La xarxa de GPS CuaTeNeo es va instal•lar l'any 1996 a les Bètiques orientals amb l'objectiu de determinar l'activitat tectònica de l'EBSZ (específicament de les falles de Carboneras, Palomares i Alhama de Murcia). La xarxa està formada per 15 monuments altament estables localitzats a les províncies de Murcia i Almeria. La xarxa s'ha observat cinc vegades: en el 1997, 2002, 2006, 2009 i 2011. Els resultats presentats en aquesta tesi es basen en l'anàlisi de les mesures d'aquestes cinc campanyes (per un període de 15 anys) així com mesures d'estacions GPS contínues de diverses xarxes públiques com la xarxa REGAM, MERISTEMUM, IGN i RAP. A més, s'han inclòs algunes estacions dissenyades especialment per a la detecció de deformacions corticals: l'estació GATA, emplaçada al Cabo de Gata i quatre estacions de la xarxa Topo-Iberia. El tret més important del camp de velocitats GPS obtingut és l'orientació cap al NW de la majoria d'estacions, amb unes taxes de desplaçament de 0,5 a 3 mm/a (respecte Europa occidental). Aquest tipus de deformació indica que la principal força responsable de les velocitats obtingudes està relacionada amb l'actual convergència entre les plaques de Nubia i Euràsia. El camp de deformació obtingut mostra evidències de deformació relacionada amb falles actives dins l'àrea d'estudi. La major part de la deformació es concentra en l'àrea delimitada per les falles d'Alhama de Murcia (AMF) i Palomares (PF), on s'han observat les màximes deformacions per cisalla. La taxa de lliscament horitzontal geodèsica estimada d'1,5±0,3 mm/a pel sistema AMF-PF i orientat oblic a la traça de la falla, indica una combinació de moviment invers i levògir. Aquesta taxa de lliscament màxima s'atribueix a AMF degut a que PF és actualment inactiva o presenta taxes de lliscament molt lentes, imperceptibles en aquest estudi GPS. La instal•lació de l'estació GATA ens ha permès disposar d'observacions continues als dos costats de la zona de falla de Carboneras (CFZ). Per primera vegada, ha estat possible la quantificació geodèsica de la taxa de lliscament de CFZ: una taxa màxima en direcció senestra d'1,3±0,2 mm/a. La coincidència de les taxes geològiques i geodèsiques al llarg de la CFZ, posen de manifest que durant el Quaternari el segment nord de la CFZ ha estat tectònicament actiu i ha estat lliscant a una taxa constant d'1,1 a 1,5 mm/a. Les velocitats GPS obtingudes i el camp de deformació derivat d'aquestes suggereixen una compressió dominant orientada NW-SE, amb una extensió SW-NE en la part SW de l'àrea d'estudi. En aquest sector del SW, prop d'Almeria, la predominança d'émax indica la presència d'una cinemàtica d'aprimament o extensional, relacionada a una tectònica d'escapament de blocs i possiblement a un slab rollback. Aquest treball posa de manifest l'activitat tectònica continua en l'actualitat a les Bètiques orientals i determina que les falles senestres d'Alhama de Murcia i Carboneras són les més actives. Ambdues falles juguen un paper important en la cinemàtica de la convergència de plaques regional.[eng] The eastern Betic Cordillera, south-eastern Spain, is one of the most seismically active area within the Iberian Peninsula. The Eastern Betic Shear Zone (EBSZ) in the Betic Cordillera absorbs part of the convergence between the Eurasia and African (Nubia) plates, stretching for aprox. 250 km from Alicante to Almeria. The EBSZ is a NE-SW transpressive left-lateral trending fault-system that is composed by several individual faults. Listed from south to north: Carboneras, Palomares, Alhama de Murcia, Carrascoy and Bajo-Segura. The CuaTeNeo GPS network was installed in 1996 in the eastern Betics with the main goal of determining the ongoing activity of the EBSZ (specifically of the Carboneras, Palomares and Alhama de Murcia faults). The network consists of 15 highly stable monuments, covering an area of 120x50 km in Murcia and Almeria. The network has been observed five times in 1997, 2002, 2006, 2009 and 2011. The results presented here are based on the analysis of the data of these five campaigns, spanning 15 year long time period and the data from continuous GPS stations of various public networks, such as REGAM, MERISTEMUM, IGN and RAP. In addition, several stations specially designed to detect tectonic crustal deformations have also been included: GATA station from Cabo de Gata and four Topo-Iberia network stations located within the study area. The most prominent feature of the GPS velocity field is the NW oriented motion of the majority of the stations at rates ranging from 0.5 to 3 mm/yr in a western Europe reference frame. 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 observed deformation is concentrated in the area delimited by the Alhama de Murcia (AMF) and Palomares (PF) faults. Here the maximum shear strain rates are observed. An estimated geodetic slip rate of the AMF-PF fault system is 1.5±0.3 mm/yr, oriented obliquely to the strike of the fault and indicating a combination of reverse and sinistral type of motion. We attribute this maximum slip rate to AMF since PF is currently either inactive or is slipping very slowly, at rates that are undetectable by the current GPS station spatial-temporal coverage. The installation of the GATA GPS station at Cabo de Gata has enabled us to obtain continuous observations from both sides of the Carboneras fault zone (CFZ) in the southern part of the study area. For the first time, it was possible to quantify the slip rate of the CFZ: a maximum left-lateral strike slip motion of 1.3±0.2 mm/yr. The coincidence of the geologic and geodetic strike-slip rates along the CFZ, illustrate that during Quaternary the northern segment of the CFZ has been tectonically active and has been slipping at a constant rate ranging from 1.1 to 1.5 mm/yr. GPS velocities and the derived strain rate field suggest a dominant NW-SE oriented compression, with a SW-NE extension in the south-western part of the study area, west of Almeria. In this SW sector the dominance of Erna., indicate a presence of a thinning or extensional kinematics, related to the block escape tectonics and possibly a slab rollback. This work demonstrates the current continuing tectonic activity of the eastern Betics and determines that Alhama de Murcia and Carboneras left-lateral faults are the most active faults. These two faults play an important role in the regional plate convergence kinematics

Present-day crustal deformation field of the Iberian Peninsula estimated by GPS measurements

We present the crustal deformation field in the Iberian Peninsula and northern Morocco, based on the analysis of the continuous GPS (CGPS) observations for the last five years, combined with the survey style observations (SGPS) of the CuaTeNeo network in eastern Betics. The analyzed CGPS stations come from several national and regional GNSS networks, with variable monument design and stability. Four CuaTeNeo campaigns were conducted with approximately a 4-year interval from 1997 to 2011. Although the calculated deformation field is complex, some expected features could be easily identified. Considering the Eurasia fixed frame, the highest velocities, as expected, are observed in Morocco, where the velocities reach 4.7±0.2 mm/yr. In southern Spain, stations located west of Almeria exhibit a westerly trend of motion, which reach 3.2±0.1 mm/yr at station SFER. The direction of these vectors makes us think that the main driving force behind the observed deformations cannot be solely attributed to the Africa-Eurasia convergence, but it should be due to the deeper geodynamic processes related to the subduction of the Betic-Alboran slab