Análisis morfométrico cuantitativo para la caracterización tectónica del norte de Túnez

Màster Oficial en Recursos Minerals i Riscos Geològics, Universitat de Barcelona - Universitat Autònoma de Barcelona, Facultat de Geologia, Curs: 2015-2016, Tutors: César Rodríguez Ranero, Eulàlia Gràcia Mont i María Ortuño CandelaNorthern Tunisia is characterized by low deformation rates and low to moderate seismicity. Although instrumental seismicity reaches maximum magnitudes of Mw 5.5, some historical earthquakes were described with catastrophic consequences in this region. Aiming to improve our knowledge of active tectonics in Tunisia, we carried out a quantitative morphometric analysis in the northwestern region. We applied different morphometric indices, like river profiles, knickpoint analysis, curves and hypsometric integrals and drainage pattern anomalies in order to differentiate between zones with high or low recent tectonic activity. These indices allow identifying uplift and subsidence zones, which we relate to fault activity. A selected sector was studied with a field campaign to test the results obtained with the quantitative analysis. During the field work we identified geological evidence of recent activity and a considerable seismogenic potential along El Alia-Teboursouk (ETF) and Dkhila (DF) faults. Geological evidence include fluvial terraces folded by faults, striated pebbles, wind gaps, clastic dikes, sand volcanoes, coseismic cracks, etc. To estimate the seismic potential of this region and obtain a first seismic hazard estimation, we interpreted fault segmentation affected by a potentially coseismic rupture. Then, we calculated earthquake magnitude expected for each segments using two empirical equations, which relate rupture length and maximum magnitude. Magnitude for each entire fault was also calculated to provide an upper bound. Our study provides evidence of active tectonics in this region, with potential magnitudes ranging from Mw 6 to 7.8. Although not reflected in the instrumental seismicity, our results support an important seismic hazard, evidenced by the several active tectonic structures identified and the two seismogenic faults described. The ETF fault could be responsible of one of the most debastating historical earthquakes in northern Tunisia that destroyed Utique in 412 A.D

Caracterización de grandes estructuras sismogénicas y tsunamogénicas del Golfo de Cádiz con tecnologías de muy alta resolución : Cruise Report INSIGHT-Leg 1

Cruise Report INSIGHT-Leg 1 R/V Sarmiento de Gamboa (SDG-68) 29th April - 18th May 2018.-- 139 pages, figures, tables, 2 annexesLarge earthquakes, submarine landslides and the tsunami they might originate are geohazards of great societal concern because they may impact world economies and struck coastal populations. Examples of these events are the 2004 northern Sumatra and 2011 Tohoku earthquakes and respective tsunamis. However, earthquakes of magnitude Mw > 8.0 in areas of relatively slow tectonic deformation and with long recurrence intervals, such as the external part of the Gulf of Cadiz, might also have a significant impact. The most relevant is the 1755 Lisbon earthquake, related submarine landslides and destructive tsunami. The occurrence of faults and landslides able to trigger a catastrophic tsunami reveals that the Gulf of Cadiz is one of the highest geohazard areas in Europe. Migration of sub-seafloor fluids has also been widely documented in the Gulf of Cadiz and such fluids are strongly related to the earthquake cycle and to the occurrence of submarine landslides. Understanding of these active processes can only be developed by using ultra-high-resolution tools able to map with unprecedented detail faults, submarine landslides and fluid escape structures. State-of-the-art techniques are used during INSIGHT-Leg 1, such as microbathymetry obtained from an autonomous underwater vehicle (AUV), sub-bottom profiles, HR multi-channel seismic data (MCS), and groundtruthing using sediment coresWe gratefully acknowledge financial support from Ministerio Economia y Competividad through national project INSIGHT “ImagiNg large SeismogenIc and tsunamiGenic structures of the Gulf of Cadiz with ultra-High resolution Technologies (INSIGHT-Leg1)” (CGL2011-30005-C02-02, PIs: Roger Urgeles and Eulàlia Gràcia) and Ocean Facilities Exchange Group (OFEG) for allowing us to use the AUVs “Abyss” from GEOMAR (Germany

Antithrombotic treatment in elderly patients with atrial fibrillation: a practical approach

Background: Atrial fibrillation (AF) in the elderly is a complex condition. It has a direct impact on the underuse of antithrombotic therapy reported in this population. Discussion: All patients aged >= 75 years with AF have an individual yearly risk of stroke > 4 %. However, the risk of hemorrhage is also increased. Moreover, in this population it is common the presence of other comorbidities, cognitive disorders, risk of falls and polymedication. This may lead to an underuse of anticoagulant therapy. Direct oral anticoagulants (DOACs) are at least as effective as conventional therapy, but with lesser risk of intracranial hemorrhage. The simplification of treatment with these drugs may be an advantage in patients with cognitive impairment. The great majority of elderly patients with AF should receive anticoagulant therapy, unless an unequivocal contraindication. DOACs may be the drugs of choice in many elderly patients with AF. Summary: In this manuscript, the available evidence about the management of anticoagulation in elderly patients with AF is reviewed. In addition, specific practical recommendations about different controversial issues (i.e. patients with anemia, thrombocytopenia, risk of gastrointestinal bleeding, renal dysfunction, cognitive impairment, risk of falls, polymedication, frailty, etc.) are provided

Documento de la Sociedad Española de Hipertensión-Liga Española para la Lucha contra la Hipertensión Arterial (SEH-LELHA) sobre las guías ACC/AHA 2017 de hipertensión arterial

The American College of Cardiology (ACC) and the American Heart Association (AHA) have recently published their guidelines for the prevention, detection, evaluation, and management of hypertension in adults. The most controversial issue is the classification threshold at 130/80 mmHg, which will allow a large number of patients to be diagnosed as hypertensive who were previously considered normotensive. Blood pressure (BP) is considered normal (<120 mmHg systolic and <80 mmHg diastolic), elevated (120-129 and <80 mmHg), stage 1 (130-139 or 80-89 mmHg), and stage 2 (≥140 or ≥90 mmHg). Out-of-office BP measurements are recommended to confirm the diagnosis of hypertension and for titration of BP-lowering medication. In management, cardiovascular risk would be determinant since those with grade 1 hypertension and an estimated 10-year risk of atherosclerotic cardiovascular disease ≥10%, and those with cardiovascular disease, chronic kidney disease and/or diabetes will require pharmacological treatment, the rest being susceptible to non-pharmacological treatment up to the 140/90 mmHg threshold. These recommendations would allow patients with level 1 hypertension and high atherosclerotic cardiovascular disease to benefit from pharmacological therapies and all patients could also benefit from improved non-pharmacological therapies. However, this approach should be cautious because inadequate BP measurement and/or lack of systematic atherosclerotic cardiovascular disease calculation could lead to overestimation in diagnosing hypertension and to overtreatment. Guidelines are recommendations, not impositions, and the management of hypertension should be individualized, based on clinical decisions, preferences of the patients, and an adequate balance between benefits and risks

Active tectonics in Northern Africa: The Nubia-Eurasia boundary in Tunisia

[eng] This PhD thesis presents a geological and geophysical study that characterizes the Quaternary stratigraphy, geomorphology, recent tectonics, and discusses their implications to understand the geodynamic evolution of North Tunisia, including the emerged land and continental margin. The study area spans much of the region containing the boundary between the African and Eurasian tectonic plates in this sector. I have carried out specific analyses for an onshore and an offshore contiguous regions, where present-day tectonics has been previously poorly studied. Onshore Northern Tunisia we applied a morphometric relief analysis of digital elevation models based in drainage network metrics to characterize active tectonics and its influence into the drainage evolution of the area. This analysis was ground-truthed with a field campaign. Our analysis indicates that recent river captures have been the main factor driving the fluvial network reorganization in Northern Tunisia and are probably driven by the gradual uplift of adjacent axial valleys by reverse/oblique slip faults or associated folding. Several active faults with estimated maximum magnitudes up to (Mw) 6.7 have been identified. To study the offshore North Tunisian continental margin we have integrated a comprehensive dataset of about 12,000 km of 2D parametric echosounder profiles and about 15,600 km2 of high- resolution bathymetry and back-scatter mosaics from two cruises. Additionally to the geophysical dataset, we integrated available age data from a giant piston core collected by the R/V Marion Dufresne in 1995 during the MAST II PALAEOFLUX Program, which provides the calibration of horizons mapped with TOPAS profiles. This large dataset permitted a detailed analysis of the offshore Tunisian plateau for the first time. The geomorphologic and morpho-structural study of the offshore North Tunisian margin has revealed a complex seafloor topography. The coexistence of a wide range of geomorphic features interplay to shape the seafloor and shallow strata structure. This first high-resolution study has been key to later identify and characterize active faulting and related structures. The seismo-stratigraphic analysis of deposits supports that individual Quaternary basins develop syn-tectonic to faulting. This analysis found a change in Sediment Accumulation Rates (SAR) coeval to a change in the strata geometry of the units next to faults at 402 ± 5 ky (mid Middle Pleistocene) supporting a change in active faulting intensity caused by enhanced contractional tectonics. This change may relate to the NW-SE convergence between Nubia and Eurasia, and probably marks the end of the Tyrrhenian back-arc extension and of subduction trench migration in the Ionian Sea. The structural analysis of the offshore North Tunisian continental margin has revealed a series of active faults, mapped for the first time in the region, with a general transpressional to compressional regime and estimated maximum magnitudes of (Mw) 7.54. Most active faults occur within the north-eastern sector of the mapped area and possibly represent the current reactivation of previous structures and inverted in compression by the present-day NW-SE trending convergence. Most of them are possibly pre-existing faults formed during the opening of the Tyrrhenian Sea and some fewer faults are possibly related to the fold-and-thrust belt system associated to the opening of the Algero-Balearic basin. Overall, the distribution of active faults corresponds to a sparse seismicity band that expands further south than in neighbouring regions. The broad area of deformation is probably related to the geometry and dynamics of the slab underlying Tunisia, and to the collision of the North African lithosphere with relatively thick continental lithosphere of the Sardinia-Corsica. The results of this thesis provide information to improve the regional seismic hazard assessment.[cat] Aquesta tesi presenta un estudi geològic i geofísic que caracteritza l’estratigrafia quaternària, la geomorfologia i l’activitat tectònica recent per entendre l’evolució geodinàmica del Nord de Tunísia, incloent la zona emergida i el marge continental. L’àrea d’estudi inclou la major part de la regió que conté el límit de plaques entre Núbia i Euràsia en aquest sector. A la zona emergida s’ha dut a terme una anàlisi morfomètrica del relleu mitjançant models digitals del terreny per caracteritzar la tectònica recent i la seva influència en l’evolució de la xarxa de drenatge. Aquest estudi es va complementar amb una campanya de camp i ha permès comprovar que les recents captures dels rius provocades pel moviment de falles actives són el principal factor que està causant una reorganització de la xarxa. A més, s’han identificat noves falles actives amb magnituds de terratrèmols estimades de fins a 6.7 Mw. A la zona marina es van adquirir una gran quantitat de dades en dues campanyes, incloent 12.000 km de perfils d’ecosonda i un mapa batimètric d’uns 15.600 km2. Aquestes dades van permetre dur a terme un estudi geomorfològic que ha descobert un fons marí molt complex. També es va dur a terme un estudi sismoestratigràfic dels sediments quaternaris que ha demostrat que les conques sedimentàries recents es desenvolupen sintectònicament a falles. Amb aquesta anàlisi es va identificar un canvi en les taxes de sedimentació a 402 ± 5 ka que demostra un augment en l’activitat de falles degut a la convergencia de plaques actual i que probablement marca la fi de la subducció a la conca del Tirrè. Per altra banda, es va dur a terme una anàlisi estructural del marge continental amb el que es van identificar nombroses falles actives desconegudes anteriorment i de les que s’han obtingut magnituds potencials de terratrèmols de fins a 7.54 Mw. Aquestes falles són falles reactivades de l’obertura del Tirrè i en menor mesura de l’obertura de la conca Algero-Balear. Finalment, es proposa que la gran banda de deformació transpressiva-compressiva de Tunísia està relacionada amb la geometria i dinàmica dels slabs i al fet que el marge de Tunísia està col·lisionant amb l’escorça continental del bloc de Sardenya- Còrsega

Quantitative morphometric analysis for the tectonic characterisation of northern Tunisia

Trabajo final presentado por Miquel Camafort Blanco para un Máster de la Universitat de Barcelona (UB), realizado bajo la dirección del Dr. César Rodríguez Ranero y de la Dra. Eulàlia Gràcia Mont del Institut de Ciències del Mar (ICM-CSIC)Peer Reviewe

Active tectonics in Northern Africa: The Nubia-Eurasia boundary in Tunisia

This PhD thesis presents a geological and geophysical study that characterizes the Quaternary stratigraphy, geomorphology, recent tectonics, and discusses their implications to understand the geodynamic evolution of North Tunisia, including the emerged land and continental margin. The study area spans much of the region containing the boundary between the African and Eurasian tectonic plates in this sector. I have carried out specific analyses for an onshore and an offshore contiguous regions, where present-day tectonics has been previously poorly studied. Onshore Northern Tunisia we applied a morphometric relief analysis of digital elevation models based in drainage network metrics to characterize active tectonics and its influence into the drainage evolution of the area. This analysis was ground-truthed with a field campaign. Our analysis indicates that recent river captures have been the main factor driving the fluvial network reorganization in Northern Tunisia and are probably driven by the gradual uplift of adjacent axial valleys by reverse/oblique slip faults or associated folding. Several active faults with estimated maximum magnitudes up to (Mw) 6.7 have been identified. To study the offshore North Tunisian continental margin we have integrated a comprehensive dataset of about 12,000 km of 2D parametric echosounder profiles and about 15,600 km2 of high- resolution bathymetry and back-scatter mosaics from two cruises. Additionally to the geophysical dataset, we integrated available age data from a giant piston core collected by the R/V Marion Dufresne in 1995 during the MAST II PALAEOFLUX Program, which provides the calibration of horizons mapped with TOPAS profiles. This large dataset permitted a detailed analysis of the offshore Tunisian plateau for the first time. The geomorphologic and morpho-structural study of the offshore North Tunisian margin has revealed a complex seafloor topography. The coexistence of a wide range of geomorphic features interplay to shape the seafloor and shallow strata structure. This first high-resolution study has been key to later identify and characterize active faulting and related structures. The seismo-stratigraphic analysis of deposits supports that individual Quaternary basins develop syn-tectonic to faulting. This analysis found a change in Sediment Accumulation Rates (SAR) coeval to a change in the strata geometry of the units next to faults at 402 ± 5 ky (mid Middle Pleistocene) supporting a change in active faulting intensity caused by enhanced contractional tectonics. This change may relate to the NW-SE convergence between Nubia and Eurasia, and probably marks the end of the Tyrrhenian back-arc extension and of subduction trench migration in the Ionian Sea. The structural analysis of the offshore North Tunisian continental margin has revealed a series of active faults, mapped for the first time in the region, with a general transpressional to compressional regime and estimated maximum magnitudes of (Mw) 7.54. Most active faults occur within the north-eastern sector of the mapped area and possibly represent the current reactivation of previous structures and inverted in compression by the present-day NW-SE trending convergence. Most of them are possibly pre-existing faults formed during the opening of the Tyrrhenian Sea and some fewer faults are possibly related to the fold-and-thrust belt system associated to the opening of the Algero-Balearic basin. Overall, the distribution of active faults corresponds to a sparse seismicity band that expands further south than in neighbouring regions. The broad area of deformation is probably related to the geometry and dynamics of the slab underlying Tunisia, and to the collision of the North African lithosphere with relatively thick continental lithosphere of the Sardinia-Corsica. The results of this thesis provide information to improve the regional seismic hazard assessment.Aquesta tesi presenta un estudi geològic i geofísic que caracteritza l’estratigrafia quaternària, la geomorfologia i l’activitat tectònica recent per entendre l’evolució geodinàmica del Nord de Tunísia, incloent la zona emergida i el marge continental. L’àrea d’estudi inclou la major part de la regió que conté el límit de plaques entre Núbia i Euràsia en aquest sector. A la zona emergida s’ha dut a terme una anàlisi morfomètrica del relleu mitjançant models digitals del terreny per caracteritzar la tectònica recent i la seva influència en l’evolució de la xarxa de drenatge. Aquest estudi es va complementar amb una campanya de camp i ha permès comprovar que les recents captures dels rius provocades pel moviment de falles actives són el principal factor que està causant una reorganització de la xarxa. A més, s’han identificat noves falles actives amb magnituds de terratrèmols estimades de fins a 6.7 Mw. A la zona marina es van adquirir una gran quantitat de dades en dues campanyes, incloent 12.000 km de perfils d’ecosonda i un mapa batimètric d’uns 15.600 km2. Aquestes dades van permetre dur a terme un estudi geomorfològic que ha descobert un fons marí molt complex. També es va dur a terme un estudi sismoestratigràfic dels sediments quaternaris que ha demostrat que les conques sedimentàries recents es desenvolupen sintectònicament a falles. Amb aquesta anàlisi es va identificar un canvi en les taxes de sedimentació a 402 ± 5 ka que demostra un augment en l’activitat de falles degut a la convergencia de plaques actual i que probablement marca la fi de la subducció a la conca del Tirrè. Per altra banda, es va dur a terme una anàlisi estructural del marge continental amb el que es van identificar nombroses falles actives desconegudes anteriorment i de les que s’han obtingut magnituds potencials de terratrèmols de fins a 7.54 Mw. Aquestes falles són falles reactivades de l’obertura del Tirrè i en menor mesura de l’obertura de la conca Algero-Balear. Finalment, es proposa que la gran banda de deformació transpressiva-compressiva de Tunísia està relacionada amb la geometria i dinàmica dels slabs i al fet que el marge de Tunísia està col·lisionant amb l’escorça continental del bloc de Sardenya- Còrsega

Tectónica activa en el norte de África: el límite entre Nubia y Europa en Túnez

Memoria de tesis doctoral presentada por Miquel Camafort Blanco para obtener el título de Doctor en Ciencias de la Tierra por la Universitat de Barcelona (UB), realizada bajo la dirección del Dr. César Rodríguez Ranero y de la Dra. Eulàlia Gràcia i Mont del Institut de Ciències del Mar (ICM-CSIC).-- 266 pages, figuresThis PhD thesis presents a geological and geophysical study that characterizes the Quaternary stratigraphy, geomorphology, recent tectonics, and discusses their implications to understand the geodynamic evolution of North Tunisia, including the emerged land and continental margin. The study area spans much of the region containing the boundary between the African and Eurasian tectonic plates in this sector. The onshore main structural pattern strikes in a NE-SW trend that extends offshore, into the North Tunisian continental margin plateau that is part of the same recent deformation system. I have carried out specific analyses of these two onshore and offshore regions where present-day tectonics has been previously poorly studied. Although some limited activetectonic studies had been carried out onshore, the offshore area was scarcely studied to date, and never explored in the detail presented in this work, let alone studied in an onshore-offshore integrative study. To carry out the joint study of the two regions we have had to take different methodological approaches. Onshore Northern Tunisia we applied a morphometric relief analysis of digital elevation models based in drainage network metrics to characterize active tectonics and its influence into the drainage evolution of the area. This analysis was ground-truthed with a field campaign in March 2015 to examine the several morphometric anomalies obtained with the relief analysis carried out before. Our analysis indicates that recent river captures have been the main factor driving the fluvial network reorganization in Northern Tunisia. Morphometric indices evidence fluvial network reorganization that indicates that the catchment area of the Medjerda River has increased through time by capturing adjacent axial valleys to the east of its previous drainage divide. These captures are probably driven by the gradual uplift of adjacent axial valleys by reverse/oblique slip faults like El Alia-Teboursouk and Dkhila faults or associated folding. Our fieldwork discovered that these faults cut Pleistocene sediments and possible associated coseismic structures were identified, further supporting recent fault activity with estimated maximum magnitudes (Mw) of 6.7 and 6.5 respectively for each fault. [...]The author of this thesis has been supported by the project Geomargen-2 funded by Repsol and EU project EMODnet-HRSM. Additional funding has been obtained on the framework of SHAKE (CGL2011-30005-C02-02) and INSIGHT (CTM2015-70155-R) projects. This work was carried out within the Grup de Recerca Consolidat de la Generalitat de Catalunya Barcelona Centre for Subsurface Imaging (B-CSI) (2017SGR1662

Tectónica activa en el margen continental sumergido del norte de Túnez

Inciativa Ibérica para el Estudio de las Fallas Activas, Tercera Reunión Ibérica sobre Fallas Activas y Paleosismología IBERFAULT 2018 - Third Iberian Meeting on Active Faults and Paleoseismology, 11-13 June 2018, Alicante, Spain.-- 3 pages, 2 figuresNorthern Tunisia has a complex and poorly studied tectonic evolution. Particularly, the offshore sector of the continental margin in northern Tunisia comprised between Sicily and Sardinia is a poorly explored area within the Mediterranean Sea and very few works and datasets have been published until now. In order to study the current tectonic activity of the area we use a large dataset from two geophysical cruises that collected a high-resolution bathymetric map covering ~15,600 km2 and around 12,000 km of parametric sub-bottom profiles. We use the data for a geomorphological, seismostratigraphical and structural analysis. We find active faulting mainly affecting the north-easternmost sector of the studied region. Active faulting displays a transpressive regime with NE-SW oriented left-lateral strike slip faults that matches with the current NW-SE convergence between Nubia and Eurasia and differs from the pattern observed at the neighbour areas of northern Algeria and northern SicilyThis research project was funded by Repsol Exploración S.A.Peer Reviewe

Active Tectonics of the North Tunisian Continental Margin

20 pages, 19 figures, 1 table.-- Data Availability Statement: The original seismic images and maps used for this publication are available online (at https://doi.org/10.5281/zenodo.6350585A poorly defined boundary between the Nubia and Eurasian plates runs along the Northern Tunisian continental margin. The Tunisia margin is deformed by a slow NW–SE trending convergence resulting in a diffuse deformation zone with scarce and scattered seismicity compared to the seismic activity into the neighboring regions to the east and west along the boundary. The area has been poorly studied and therefore its recent evolution is almost unknown, particularly offshore. Here, we present a structural analysis of the active tectonics in this submarine continental margin. The data used for this analysis are high-resolution bathymetric maps together with parametric echosounder images which have allowed to obtain a map of active faulting with unprecedented detail. The structural analysis supports a dominantly transpressive to compressive component of faulting, resulting from the current regional NW–SE trending compressive regime between plates. The North-eastern Domain of the study region contains the highest number of active faults with numerous pockmarks aligned along them. This study shows that the plate boundary across the North Tunisia margin is incipient and poorly developed, which may be due to the fact that deformation is partitioned over a large number of structures, each accommodating a small percentage of convergence, with the exception of the Hayat fault system. The Hayat reverse fault, striking WSW–ENE, is the largest fault system that comparatively may accommodate a greater amount of displacement, and is probably responsible for the uplift of the North-eastern Domain of the continental marginData collection and MC were supported by the project Geomargen-2 funded by REPSOL. The work was also supported by the EU project EMODnet-HRSM-2. Additional funding came from the Spanish Ministry of Science and Innovation projects: CTM2011-30400-C02-01 “HADES,” CGL2011-30005-C02-02 “SHAKE,” CTM2015-70155-R “INSIGHT,” PID2019-104668RB-I00 “STRENGTH,” CTM2015-71766-R “FRAME,” and PID2019-109559RB-I00 “ATLANTIS.” ICM has also had funding support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)Peer reviewe