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The Eastern Mediterranean is the most seismically active region in Europe due to the complex interactions of the Arabian, African, and Eurasian tectonic plates. Deformation is achieved by faulting in the brittle crust, distributed flow in the viscoelastic lower-crust and mantle, and Hellenic subduction, but the long-term partitioning of these mechanisms is still unknown. We exploit an extensive suite of geodetic observations to build a kinematic model connecting strike-slip deformation, extension, subduction, and shear localization across Anatolia and the Aegean Sea by mapping the distribution of slip and strain accumulation on major active geological structures. We find that tectonic escape is facilitated by a plate-boundary-like, trans-lithospheric shear zone extending from the Gulf of Evia to the Turkish-Iranian Plateau that underlies the surface trace of the North Anatolian Fault. Additional deformation in Anatolia is taken up by a series of smaller-scale conjugate shear zones that reach the upper mantle, the largest of which is located beneath the East Anatolian Fault. Rapid north–south extension in the western part of the system, driven primarily by Hellenic Trench retreat, is accommodated by rotation and broadening of the North Anatolian mantle shear zone from the Sea of Marmara across the north Aegean Sea, and by a system of distributed transform faults and rifts including the rapidly extending Gulf of Corinth in central Greece and the active grabens of western Turkey. Africa–Eurasia convergence along the Hellenic Arc occurs at a median rate of 49.8 mm yr–1 in a largely trench-normal direction except near eastern Crete where variably oriented slip on the megathrust coincides with mixed-mode and strike-slip deformation in the overlying accretionary wedge near the Ptolemy–Pliny–Strabo trenches. Our kinematic model illustrates the competing roles the North Anatolian mantle shear zone, Hellenic Trench, overlying mantle wedge, and active crustal faults play in accommodating tectonic indentation, slab rollback and associated Aegean extension. Viscoelastic flow in the lower crust and upper mantle dominate the surface velocity field across much of Anatolia and a clear transition to megathrust-related slab pull occurs in western Turkey, the Aegean Sea and Greece. Crustal scale faults and the Hellenic wedge contribute only a minor amount to the large-scale, regional pattern of Eastern Mediterranean interseismic surface deformation. [ABSTRACT FROM AUTHOR]

Oblique convergence across Tibet leads to slip partitioning with the coexistence of strike-slip, normal and thrust motion on major fault systems. A key point is to understand and model how faults interact and accumulate strain at depth. Here, we extract ground deformation across the Haiyuan Fault restraining bend, at the northeastern boundary of the Tibetan plateau, from Envisat radar data spanning the 2001-2011 period.We show that the complexity of the surface displacement field can be explained by the partitioning of a uniform deep-seated convergence. Mountains and sand dunes in the study area make the radar data processing challenging and require the latest developments in processing procedures for Synthetic Aperture Radar interferometry. The processing strategy is based on a small baseline approach. Before unwrapping, we correct for atmospheric phase delays from global atmospheric models and digital elevation model errors. A series of filtering steps is applied to improve the signal-to-noise ratio across high ranges of the Tibetan plateau and the phase unwrapping capability across the fault, required for reliable estimate of fault movement. We then jointly invert our InSAR time-series together with published GPS displacements to test a proposed long-term slip-partitioning model between the Haiyuan and Gulang left-lateral Faults and the Qilian Shan thrusts. We explore the geometry of the fault system at depth and associated slip rates using a Bayesian approach and test the consistency of present-day geodetic surface displacements with a longterm tectonic model. We determine a uniform convergence rate of 10 [8.6-11.5]mm yr-1 with an N89 [81-97]°E across the whole fault system, with a variable partitioning west and east of a major extensional fault-jog (the Tianzhu pull-apart basin). Our 2-D model of two profiles perpendicular to the fault system gives a quantitative understanding of how crustal deformation is accommodated by the various branches of this thrust/strike-slip fault system and demonstrates how the geometry of the Haiyuan fault system controls the partitioning of the deep secular motion. [ABSTRACT FROM AUTHOR]

Introduction La désinsertion de l’aiguille veineuse est une complication sévère à l’origine de morbi-mortalité en hémodialyse. Elle est très souvent imprévisible. La fréquence de cette complication est mal connue et sous-estimée. Notre centre lourd comprend 60 postes et assure environ 45 000 séances annuelles. Entre avril 2015 et mars 2016, 15 désinsertions d’aiguilles veineuses se sont produites soit 1 désinsertion pour 3035 séances. Quatre patients ont nécessité une prise en charge réanimatrice avec transfusions. Patients/Matériels et méthodes Les premiers événements ont fait l’objet de CREX. Un groupe de travail a ensuite été mis en place dans le cadre d’une EPP en mars 2016. Le travail a porté sur l’analyse du matériel (set de branchement), l’impact du changement récent de désinfectant, la révision des procédures de fixation des aiguilles, la rédaction et la diffusion d’un livret d’information pour les patients, l’instauration d’une consultation première ponction à visée éducative, la mise en place d’un outils spécifique de déclaration, la mise en place d’un groupe pluri-professionnel et la réalisation d’audits réguliers sur la qualité de la fixation basée sur la procédure et les recommandations. Les résultats des audits annuels ont été diffusés et chaque nouvel événement a fait l’objet d’une alerte et d’une analyse. Observation/Résultats En mars 2018, 66 IDE sur 73 ont été évaluées. Cent-douze branchements ont été audités et analysés : 50 % sur aiguilles métalliques, 50 % sur angiocath. La double cravate est présente dans 90 %, le petit pont dans 75 %, la boucle de sécurité dans 95 % et la procédure est connue des IDE dans 100 % contre respectivement 14 %,43 %, 89 % et 32 % en 2016. En outre le moniteur est du côté de l’abord vasculaire dans 100 % et un prolongateur est présent dans 91 % en présence d’un angiocath (Tableau 1). Discussion Le dispositif d’alerte a montré son efficience et a été étendu à d’autres structures de l’AURA. Ce programme montre l’impact favorable de l’autoévaluation dans l’amélioration des pratiques et la gestion des risques en hémodialyse. Il a permis de mobiliser et fédérer les équipes autour de cette problématique et plus largement de la gestion des abords vasculaires. Il démontre qu’il est possible de prévenir la désinsertion de l’aiguille veineuse par le strict respect des recommandations. [ABSTRACT FROM AUTHOR]

Introduction Les patients en hémodialyse présentent un risque 10 à 20 fois plus important d’arrêt cardiaque (AC) que la population générale. Le pronostic pourrait être amélioré par la formation des soignants aux gestes d’urgence. L’AURA Paris Plaisance prend en charge 320 patients chaque semaine en hémodialyse. Une équipe est dédiée à la formation du personnel soignant en utilisant des techniques pédagogiques basées sur la simulation. L’objectif de l’étude était d’évaluer les besoins en formation sur la prise en charge de l’AR dans le centre d’hémodialyse. Patients et méthodes Une équipe multidisciplinaire a rédigé un scénario décrivant un AR pendant une séance d’hémodialyse. Un questionnaire a recueilli le degré de confiance des soignants dans la prise en charge de l’AR ainsi que leur expérience et leur formation. Après un briefing rappelant les objectifs de la session et le scénario, 2 participants disposaient de 5 minutes pour prendre en charge l’AR d’un patient en hémodialyse : un mannequin de réanimation cardiorespiratoire simulant plusieurs rhythmes cardiaques ainsi qu’un défibrillateur semi-automatique et un masque ballon étaient présents dans la pièce. Les participants étaient évalués par deux observateurs utilisant une check-list établie selon les recommandations de l’European Resuscitation Council. Résultats Soixante-quatorze soignants ont été évalués de février 2018 à avril 2018 (81,7 % de femmes, 18,3 % d’hommes, répartis en 55,4 % d’infirmier(es), 36,5 % d’aides soignant(es), 4,1 % d’ASH et 4,1 % de brancardier(es)). Vingt et un pour cent étaient âgés de moins de 30 ans, 59 % de 40 ans et plus. Au total, 20,5 % déclarent n’avoir jamais reçu de formation à l’AR. Seuls 42 % avaient déjà utilisé un défibrillateur. De plus, 60,2 % s’estiment peu ou pas du tout confiant(es) pour dans la prise en charge de l’AR. 43,2 % d’entre eux estiment « absolument avoir besoin » d’une formation complémentaire sur l’AR. Les examinateurs ont noté que le massage cardiaque n’était pas conforme aux recommandations dans 46 % des cas. La technique de ventilation et la délivrance du choc électrique était non optimale chez plus de 70 % chez soignant(es). Discussion C’est la première étude évaluant par la simulation les compétences des soignants face à un AR en hémodialyse. Conclusion La simulation peut constituer un outil d’évaluation apprécié des soignants. Les informations recueillies permettent de cibler les soignants pouvant bénéficier d’une formation complémentaire et de produire un matériel pédagogique adapté aux besoins (vidéos, cours). La standardisation de la simulation permettra de reproduire régulièrement cette évaluation. [ABSTRACT FROM AUTHOR]

Constitutive models of fault friction form the basis of physics-based simulations of seismic activity. A generally accepted framework for the slip-rate and state dependence of friction involves a thermally activated process, whereby the probability of slip along microasperities adheres to an Arrhenius law. This model, which has become widely adopted among experimentalists and theoreticians, predicts a continuous increase of the direct effect with absolute temperature, but is it observed experimentally? Leveraging comprehensive laboratory data across diverse hydrothermal, barometric, and lithological conditions, we demonstrate that, contrary to the classical view, the direct effect for a given deformation mechanism remains largely temperature-independent. Instead, the incremental shifts in the direct effect often coincide with the brittle to semi-brittle transition, across which distinct deformation mechanisms operate. These considerations challenge the validity of the classical model. Realistic constitutive laws for rock failure within the lithosphere must incorporate the contributions of multiple deformation mechanisms within active fault zones., Competing Interests: Competing interests statement:The author declares no competing interest.

Although the surface deformation of tectonic plate boundaries is well determined by geological and geodetic measurements, the pattern of flow below the lithosphere remains poorly constrained. We use the crustal velocity field of the Plate Boundary Observatory to illuminate the distribution of horizontal flow beneath the California margin. At lower-crustal and upper-mantle depths, the boundary between the Pacific and North American plates is off-centered from the San Andreas fault, concentrated in a region that encompasses the trace of nearby active faults. A major step is associated with return flow below the Eastern California Shear Zone, leading to the extrusion of the Mojave block and a re-distribution of fault activity since the Pleistocene. Major earthquakes in California have occurred above the regions of current plastic strain accumulation. Deformation is mechanically coupled from the crust to the asthenosphere, with mantle flow overlaid by a kinematically consistent network of faults in the brittle crust.

The relative motion of tectonic plates is accommodated at boundary faults through slow and fast ruptures that encompass a wide range of source properties. Near the Parkfield segment of the San Andreas fault, low-frequency earthquakes and slow-slip events take place deeper than most seismicity, at temperature conditions typically associated with stable sliding. However, laboratory experiments indicate that the strength of granitic gouge decreases with increasing temperature above 350°C, providing a possible mechanism for weakening if temperature is to vary dynamically. Here, we argue that recurring low-frequency earthquakes and slow-slip transients at these depths may arise because of shear heating and the temperature dependence of frictional resistance. Recurring thermal instabilities can explain the recurrence pattern of the mid-crustal low-frequency earthquakes and their correlative slip distribution. Shear heating associated with slow slip is sufficient to generate pseudotachylyte veins in host rocks even when fault slip is dominantly aseismic., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Deformation associated with plate convergence at subduction zones is accommodated by a complex system involving fault slip and viscoelastic flow. These processes have proven difficult to disentangle. The 2010 M w 8.8 Maule earthquake occurred close to the Chilean coast within a dense network of continuously recording Global Positioning System stations, which provide a comprehensive history of surface strain. We use these data to assemble a detailed picture of a structurally controlled megathrust fault frictional patchwork and the three-dimensional rheological and time-dependent viscosity structure of the lower crust and upper mantle, all of which control the relative importance of afterslip and viscoelastic relaxation during postseismic deformation. These results enhance our understanding of subduction dynamics including the interplay of localized and distributed deformation during the subduction zone earthquake cycle., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).)

Modeling of postseismic deformation following great earthquakes has revealed the viscous structure of the mantle and the frictional properties of the fault interface. However, for giant megathrust events, viscoelastic flow and afterslip mechanically interplay with each other during the postseismic period. We explore the role of afterslip and viscoelastic relaxation and their interaction in the aftermath of the 2011 M w (moment magnitude) 9.0 Tohoku earthquake based on a detailed model analysis of the postseismic deformation with laterally varying, experimentally constrained, rock rheology. Mechanical coupling between viscoelastic relaxation and afterslip notably modifies both the afterslip distribution and surface deformation. Thus, we highlight the importance of addressing mechanical coupling for long-term studies of postseismic relaxation, especially in the context of the geodynamics of the Japan trench across the seismic cycle., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

The strength of the lithosphere controls tectonic evolution and seismic cycles, but how rocks deform under stress in their natural settings is usually unclear. We constrain the rheological properties beneath the Taiwan orogenic belt using the stress perturbation following the 1999 Chi-Chi earthquake and fourteen-year postseismic geodetic observations. The evolution of stress and strain rate in the lower crust is best explained by a power-law Burgers rheology with rapid increases in effective viscosities from ~10 17 to ~10 19 Pa s within a year. The short-term modulation of the lower-crustal strength during the seismic cycle may alter the energy budget of mountain building. Incorporating the laboratory data and associated uncertainties, inferred thermal gradients suggest an eastward increase from 19.5±2.5°C/km in the Coastal Plain to 32±3°C/km in the Central Range. Geodetic observations may bridge the gap between laboratory and lithospheric scales to investigate crustal rheology and tectonic evolution.

Plate tectonics is one mode of mantle convection that occurs when the surface layer (the lithosphere) is relatively weak. When plate tectonics operates on a terrestrial planet, substantial exchange of materials occurs between planetary interior and its surface. This is likely a key in maintaining the habitable environment on a planet. Therefore it is essential to understand under which conditions plate tectonics operates on a terrestrial planet. One of the puzzling observations in this context is the fact that plate tectonics occurs on Earth but not on Venus despite their similar size and composition. Factors such as the difference in water content or in grain-size have been invoked, but these models cannot easily explain the contrasting tectonic styles between Earth and Venus. We propose that strong dynamic weakening in friction is a key factor. Fast unstable fault motion is found in cool Earth, while slow and stable fault motion characterizes hot Venus, leading to substantial dynamic weakening on Earth but not on Venus. Consequently, the tectonic plates are weak on Earth allowing for their subduction, while the strong plates on Venus promote the stagnant lid regime of mantle convection.

Surveillance of clandestine nuclear tests relies on a global seismic network, but the potential of spaceborne monitoring has been underexploited. We used satellite radar imagery to determine the complete surface displacement field of up to 3.5 meters of divergent horizontal motion with 0.5 meters of subsidence associated with North Korea's largest underground nuclear test. Combining insight from geodetic and seismological remote sensing, we found that the aftermath of the initial explosive deformation involved subsidence associated with subsurface collapse and aseismic compaction of the damaged rocks of the test site. The explosive yield from the nuclear detonation with best-fitting source parameters for 450-meter depth was 191 kilotonnes of TNT equivalent. Our results demonstrate the capability of spaceborne remote sensing to help characterize large underground nuclear tests., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Slow-slip events are earthquake-like events only with much lower slip rates. While peak coseismic velocities can reach tens of meters per second, slow-slip is on the order of 10 -7±2 m/s and may last for days to weeks. Under the rate-and-state model of fault friction, slow-slip is produced only when the asperity size is commensurate with the critical nucleation size, a function of frictional properties. However, it is unlikely that all subduction zones embody the same frictional properties. In addition to friction, plastic flow of antigorite-rich serpentinite may significantly influence the dynamics of fault slip near the mantle wedge corner. Here, we show that the range of frictional parameters that generate slow slip is widened in the presence of a serpentinized layer along the subduction plate interface. We observe increased stability and damping of fast ruptures in a semi-brittle fault zone governed by both brittle and viscoelastic constitutive response. The rate of viscous serpentinite flow, governed by dislocation creep, is enhanced by high ambient temperatures. When effective viscosity is taken to be dynamic, long-term slow slip events spontaneously emerge. Integration of rheology, thermal effects, and other microphysical processes with rate-and-state friction may yield further insight into the phenomenology of slow slip.

Understanding the rheological properties of the upper mantle is essential to develop a consistent model of mantle dynamics and plate tectonics. However, the spatial distribution and temporal evolution of these properties remain unclear. Here, we infer the rheological properties of the asthenosphere across multiple great megathrust earthquakes between 2004 and 2014 along the Sumatran subduction zone, taking advantage of decade-long continuous GPS and tide-gauge measurements. We observe transient mantle wedge flow following these earthquakes, and infer the temporal evolution of the effective viscosity. We show that the evolution of stress and strain rate following these earthquakes is better matched by a bi-viscous than by a power-law rheology model, and we estimate laterally heterogeneous transient and background viscosities on the order of ~10 17 and ~10 19  Pa s, respectively. Our results constitute a preliminary rheological model to explain stress evolution within earthquake cycles and the development of seismic hazard in the region.

The deformation of mantle and crustal rocks in response to stress plays a crucial role in the distribution of seismic and volcanic hazards, controlling tectonic processes ranging from continental drift to earthquake triggering. However, the spatial variation of these dynamic properties is poorly understood as they are difficult to measure. We exploited the large stress perturbation incurred by the 2016 earthquake sequence in Kumamoto, Japan, to directly image localized and distributed deformation. The earthquakes illuminated distinct regions of low effective viscosity in the lower crust, notably beneath the Mount Aso and Mount Kuju volcanoes, surrounded by larger-scale variations of viscosity across the back-arc. This study demonstrates a new potential for geodesy to directly probe rock rheology in situ across many spatial and temporal scales., (Copyright © 2017, American Association for the Advancement of Science.)

The deformation at well-defined, narrow plate boundaries depends on the relative plate motion, but how the deformation takes place within a distributed plate boundary zone remains a conundrum. This was confirmed by the seismological analyses of the 2012 great Wharton Basin earthquakes [moment magnitude ( M w ) 8.6], which suggested the rupture of several faults at high angles to one another. Using high-resolution bathymetry and seismic reflection data, we report the discovery of new N294°E-striking shear zones, oblique to the plate fabric. These shear zones are expressed by sets of normal faults striking at N335°E, defining the direction of the principal compressional stress in the region. Also, we have imaged left-lateral strike-slip faults along reactivated N7°E-oriented oceanic fracture zones. The shear zones and the reactivated fracture zones form a conjugate system of faults, which accommodate present-day intraplate deformation in the Wharton Basin.

The deep extension of the San Andreas Fault is believed to be creeping, but the recent observations of tectonic tremors from these depths indicate a complex deformation style. In particular, an isolated tremor source near Parkfield has been producing a sequence of low-frequency earthquakes that indicates an uncommon mechanism of stress accumulation and release. The tremor pattern regularly oscillated between three and six days from mid-2003 until it was disrupted by the 2004 magnitude 6.0 Parkfield earthquake. After that event, the tremor source ruptured only about every three days, but over the next two years it gradually returned to its initial alternating recurrence pattern. The mechanism that drives this recurrence pattern is unknown. Here we use physics-based models to show that the same tremor asperity--the region from which the low-frequency earthquakes radiate--can regularly slip in slow and fast ruptures, naturally resulting in recurrence intervals alternating between three and six days. This unusual slip behaviour occurs when the tremor asperity size is close to the critical nucleation size of earthquakes. We also show that changes in pore pressure following the Parkfield earthquake can explain the sudden change and gradual recovery of the recurrence intervals. Our findings suggest a framework for fault deformation in which the same asperity can release tectonic stress through both slow and fast ruptures.

Advances in observational, laboratory, and modeling techniques open the way to the development of physical models of the seismic cycle with potentially predictive power. To explore that possibility, we developed an integrative and fully dynamic model of the Parkfield segment of the San Andreas Fault. The model succeeds in reproducing a realistic earthquake sequence of irregular moment magnitude (M(w)) 6.0 main shocks--including events similar to the ones in 1966 and 2004--and provides an excellent match for the detailed interseismic, coseismic, and postseismic observations collected along this fault during the most recent earthquake cycle. Such calibrated physical models provide new ways to assess seismic hazards and forecast seismicity response to perturbations of natural or anthropogenic origins.