ALBERT

Beschreibung: The IUGG Yearbook is a reference document of IUGG members, administrative officers, and Association and Union Commission officers that is updated annually and distributed free of charge. Each issue endeavors to update the contact information for hundreds of persons who are actively participating in IUGG scientific activities. Information is complied throughout the year until end December. The Yearbooks are published and posted at the IUGG webpage at the beginning of the year. The Yearbooks are printed together with the Annual Reports for the preceding year in May and mailed to National Committee for Geodesy and Geophysics, Adhering Bodies, IUGG partners, and major libraries.

Beschreibung: Se descubre un misterioso crimen en un almacén. Muchas rocas han sido asesinadas. El detective Hércule Poirot emprende la investigación del caso. Para ello, contrata a un grupo de geo-científicos internacionales que buscan a los "culpables" en una campaña de perforación en los espectaculares paisajes de Chile. Los científicos encuentran pruebas del crimen en laboratorios de investigación y presentan una sorprendente solución al caso de asesinato. Esta película aborda una pregunta científica: ¿Cómo se convierte la roca en suelo en las profundidades de la superficie terrestre? Los cuatro "sospechosos" (es decir, los procesos) son las fracturas en la roca, el flujo de agua, los reactivos químicos y los microbios, los cuales se ven en acción en animaciones. Sin embargo, estas hipótesis no pueden demostrarse directamente, sólo puede demostrarse que son falsas, como una coartada en un caso criminal. Vea la película para averiguar si los investigadores logran resolver el caso. Esta película se produjo en el marco del proyecto germano-chileno "EarthShape – Earth iSurface Shaping by Biota". Puede ver de qué se trata aquí: La piel de la Tierra - donde la vida se encuentra con las rocas

Beschreibung: The Changning MS6.0 earthquake and its moderate to strong aftershocks, which occurred in the axial area of Changning anticline, exhibit different features with the moderate to strong earthquakes that occurred in the southern syncline area nearby, although these two areas are only a dozen kilometers away. Whether this difference is only caused by different fault structures, or caused by local change is still a matter of debate. In order to answer this question, basing on the correction of small earthquake location and seismic velocity structure through double-difference tomography inversion, this paper determined the fine structure of the crustal stress field by using comprehensive focal mechanism solutions, and analyzed its mechanical consistency with the focal mechanism solutions of moderate to strong earthquakes. It is found that for the different subareas of Changning area, the maximum principal stress remains horizontal, and its azimuth remains almost East-West oriented although it has a small clockwise rotation from north to south; meanwhile, the stress regime exhibit a significant local change, which is thrust stress regime for the axial area of Changning anticline, against strike-slip stress regime for the southern syncline area. The stress fields in these two subareas highly accord with the focal mechanism solutions of moderate to strong earthquakes in the corresponding area, but poorly accord with, or even contradict that in the non-corresponding area, which indicates that the local stress change of stress field is the necessary mechanical basis for the complex seismicity behavior in Changning area. Additional rock mechanics analysis points out that lateral difference of Poisson's ratio of rock is probably the main cause of this local change of stress field. This paper also discusses the seismogenic fault structure of Changning MS6.0 earthquake sequence, and suggests the activation of the basement fault(s) in the depth range of 6 to 9 km in the axial area of Changning anticline driven by regional stress field is the potential cause of the occurrence of Changning MS6.0 earthquake sequence.

Beschreibung: For a long time， with the continuous expansion of the oil and gas genesis theory and the increasing global demand for clean energy， hydrogen， as an important link connecting the theory of inorganic and organic hydrocarbon generation， as well as a promising clean energy， has gradually attracted widespread academic attention. The genesis of hydrogen in natural gas is relatively complex and diverse. According to its reaction mechanism， it can be divided into two categories： inorganic and organic. Inorganic genesis is mainly earth degassing， water rock reaction and water radiation decomposition， while organic genesis is dominated by biological action and organic matter pyrolysis. At present， hydrogen isotope and geochemical characteristics of associated gases are mainly used to identify the origin of hydrogen. However， due to the complex and diverse sources of hydrogen and its active chemical properties， it is still unable to identify the origin of hydrogen systematically and accurately. Due to the extensive genesis of hydrogen， natural gas with different hydrogen concentrations has been found in different geological conditions around the world， and the hydrogen content varies greatly （0.1%-99%）. Hydrogen can participate in hydrocarbon generation in Fischer Tropsch synthesis as a reducing agent， and also can be used as a hydrogen source to improve the hydrocarbon yield during the thermal evolution of organic matter. Therefore， the existence of hydrogen may extend the lower limit of deep gas exploration and development. Based on the systematic summary of the genetic mechanism and distribution of hydrogen， this paper discusses the energy significance of hydrogen in natural gas， and provides a reference for the future research on hydrogen rich natural gas resources.

Beschreibung: The IUGG Yearbook is a reference document of IUGG members, administrative officers, and Association and Union Commission officers that is updated annually and distributed free of charge. Each issue endeavors to update the contact information for hundreds of persons who are actively participating in IUGG scientific activities. Information is complied throughout the year until end December. The Yearbooks are published and posted at the IUGG webpage at the beginning of the year. The Yearbooks are printed together with the Annual Reports for the preceding year in May and mailed to National Committee for Geodesy and Geophysics, Adhering Bodies, IUGG partners, and major libraries.

Beschreibung: La traduction fait référence à la partie principale de la publication anglaise (Grünthal et al., 1998) décrivant l'Echelle Macrosismique Européenne (EMS-98). Ce texte est un extrait de la traduction française existante de la version anglaise complète (Grünthal et Levret, 2001). La partie princi-pale est constituée des pages 14 à 20 de l'original anglais et de la traduction de la version complète. Cette numérotation des pages est conservée ici.

Beschreibung: The translation refers to the core part of the European Macroseismic Scale (EMS-98) of the English original (Grünthal et al., 1998), respectively the core part reproduced here is an excerpt from the existing French translation of the English full version (Grünthal and Levret, 2001). The core part consists of pages 14 to 20 of both the English original and the translation of the full French version. This page numbering is retained here. The European Macroseismic Scale (EMS-98) is a tool for intensity assignment. The macroseismic intensity represents a classification of the severity of ground-motion shaking during an earthquake on the basis of observed effects at a given place. The EMS-98 is the most recent scale in general use. It fully considers the varying strength of buildings in the form of six vulnerability classes, five damage grades for both masonry and reinforced concrete structures, and differentiates structural and non-structural damage as well. Another diagnostic element concerns the relative frequency of observed effects with quantitative definitions of the qualitative terms “few, many, most.” EMS-98 is the only intensity scale complemented by comprehensive guidelines and background materials. They provide the basis that the EMS-98 can easily be adapted for use to the building stock anywhere in the world. The European Seismological Commission launched the development of a new scale in 1988 which should consider modern earthquake-resistant building types and engineering requirements. So the test version EMS-92 and then EMS-98 were evolved. The latter should be the basis for intensity evaluation in European countries and is also applied in many countries outside Europe. The English original of the EMS-98 was translated as full scale into French, Italian, Spanish and Chinese. Moreover, the core part or the short form is available in a total of altogether 30 languages. Such multilingual availability is important since persons, not always fluent in English, act as observers and sensors in macroseismology.

Beschreibung: Slab retreat, slab tearing and interactions of slabs are first-order drivers of the deformation of the overriding lithosphere. An independent description of the tectonic evolution of the back-arc and peripheral regions is a pre-requisite to test the proposed conceptual, analogue and numerical models of these complex dynamics in 3-D. We propose here a new series of detailed kinematics and tectonic reconstructions from 35 Ma to the Present shedding light on the driving mechanisms of back-arc rifting in the Mediterranean where several back-arc basins all started to form in the Oligocene. The step-by-step backward reconstructions lead to an initial situation 35 Ma ago with two subduction zones with opposite direction, below the AlKaPeCa block (i.e. belonging to the Alboran, Kabylies, Peloritani, Calabrian internal zones). Extension directions are quite variable and extension rates in these basins are high compared to the Africa-Eurasia convergence velocity. The highest rates are found in the Western Mediterranean, the Liguro-Provençal, Alboran and Tyrrhenian basins. These reconstructions are based on shortening rates in the peripheral mountain belts, extension rates in the basins, paleomagnetic rotations, pressure-temperature-time paths of metamorphic complexes within the internal zones of orogens, and kinematics of the large bounding plates. Results allow visualizing the interactions between the Alps, Apennines, Pyrenean-Cantabrian belt, Betic Cordillera and Rif, as well as back-arc basins. These back-arc basins formed at the emplacement of mountain belts with superimposed volcanic arcs, thus with thick, hot and weak crusts explaining the formation of metamorphic core complexes and the exhumation of large portions of lower crustal domains during rifting. They emphasize the role of transfer faults zones accommodating differential rates of retreat above slab tears and their relations with magmatism. Several transfer zones are identified, separating four different kinematic domains, the largest one being the Catalan-Balearic-Sicily Transfer Zone. Their integration in the wider Mediterranean realm and a comparison of motion paths calculated in several kinematic frameworks with mantle fabric shows that fast slab retreat was the main driver of back-arc extension in this region and that large-scale convection was a subsidiary driver for the pre-8 Ma period, though it became dominant afterward. Slab retreat and back-arc extension was mostly NW-SE until ∼ 20 Ma and the docking of the AlKaPeCa continental blocks along the northern margin of Africa induced a slab detachment that propagated eastward and westward, thus inducing a change in the direction of extension from NW-SE to E-W. Fast slab retreat between 32 and 8 Ma and induced asthenospheric flow have prevented the transmission of the horizontal compression due to Africa-Eurasia convergence from Africa to Eurasia and favored instead upper-plate extension driven by slab retreat. Once slab retreat had slowed down in the Late Miocene, this N-S compression was felt and recorded again from the High Atlas to the Paris Basin.

Beschreibung: This project started in October 2015 with a crazy idea : prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project.

Beschreibung: Length: 32 min ¿Qué forma los paisajes de la Tierra, con sus montañas, ríos, suelos, los lugares en los que vivimos? ¿Se forma la superficie de la Tierra cuando las rocas son levantadas por fuerzas geológicas, y luego destruidas por la lluvia, el hielo y el viento; o las plantas con sus raíces, los animales que excavan en el suelo y el gran número de microorganismos dan forma a los paisajes? Observe a los científicos del proyecto alemán-chileno "EarthShape" estudiar estas preguntas a lo largo de fascinantes paisajes de Chile, y en sus laboratorios. Una película científica diseñada y producida por Friedhelm von Blanckenburg de GFZ Potsdam, Alemania, Kirstin Übernickel de la Universidad de Tübingen, y Wolfgang Dümcke de Filmbüro Potsdam, Alemania, dentro del consorcio de investigación "EarthShape - Earth Surface Shaping by Biota", financiado por la DFG y coordinado por Todd Ehlers (Universität Tübingen) y Friedhelm von Blanckenburg (GFZ Potsdam).

Beschreibung: Length: 32 min ¿Qué es lo que forma los paisajes de la Tierra con sus montañas, ríos, suelos, los lugares en los que vivimos? La superficie de la Tierra se forma cuando las rocas son levantadas por fuerzas geológicas, y luego son destruidas por la lluvia, el hielo y el viento que tallan los paisajes por la erosión y la meteorización. Pero hay una capa verde de vida entre las rocas de abajo y el clima de arriba. ¿Las plantas con sus raíces, los animales que excavan en el suelo y el gran número de microorganismos dan forma a los paisajes? ¿O es que los minerales, el suelo y el agua proveen el ambiente para la vida? ¿O ambos son interdependientes? ¿Pueden resistir juntos el cambio climático masivo impuesto por el ser humano hoy en día? Observe a los científicos del proyecto aleman-chileno "EarthShape" estudiando estas preguntas a lo largo de un gradiente climático en Chile, en los Parques Nacionales Pan de Azúcar, La Campana y Nahuelbuta. Recorra por paisajes fascinantes y vea a los jóvenes científicos estudiando las interacciones entre la geología y la biología, desde el desierto seco de Atacama hasta los densos bosques, y en sus sofisticados laboratorios de sus instituciones. Vea cómo las retroalimentaciones controlan el clima de la Tierra.

Beschreibung: The IUGG Yearbook is a reference document of IUGG members, administrative officers, and Association and Union Commission officers that is updated annually and distributed free of charge. Each issue endeavors to update the contact information for hundreds of persons who are actively participating in IUGG scientific activities. Information is complied throughout the year until end December. The Yearbooks are published and posted at the IUGG webpage at the beginning of the year. The Yearbooks are printed together with the Annual Reports for the preceding year in May and mailed to National Committee for Geodesy and Geophysics, Adhering Bodies, IUGG partners, and major libraries.

Beschreibung: The IUGG Yearbook is a reference document of IUGG members, administrative officers, and Association and Union Commission officers that is updated annually and distributed free of charge. Each issue endeavors to update the contact information for hundreds of persons who are actively participating in IUGG scientific activities. Information is complied throughout the year until end December. The Yearbooks are published and posted at the IUGG webpage at the beginning of the year. The Yearbooks are printed together with the Annual Reports for the preceding year in May and mailed to National Committee for Geodesy and Geophysics, Adhering Bodies, IUGG partners, and major libraries.

Beschreibung: Ce projet est né en octobre 2015 avec une idée de fou: préparer et soumettre une demande de financement pour un projet de vulgarisation scientifique international, multidisciplinaire et non traditionnel… le tout en 48 heures. On dirait bien que ça a fonctionné. Un groupe de jeunes chercheurs motivés du Canada et d’Europe ont joint leurs efforts afin de réunir arts et science dans un projet de bandes dessinées sur le pergélisol (sol gelé). L’objectif de ce projet est de présenter et d’expliquer la recherche scientifique réalisée à travers l’Arctique, en mettant l’emphase sur le travail de terrain et sur l’environnement nordique en mutation. Le public-cible inclut les enfants, jeunes et moins jeunes, les parents et les enseignants, avec comme but de rendre la science du pergélisol amusante et accessible au grand public. Ce qu’il faut savoir, c’est que le pergélisol occupe une superficie de plus de vingt millions de kilomètres carrés dans l’hémisphère nord. Avec le réchauffement climatique, le pergélisol dégèle et devient plus instable sous les bâtiments, les routes et les pistes d’aéroports. Le dégel rapide d’un sol autrefois gelé perturbe également les écosystèmes, notamment la qualité de l’eau dans les milieux aquatiques, et relâche du carbone vers l’atmosphère sous forme de gaz à effet de serre, amplifiant le réchauffement. Bref, la dynamique du pergélisol face aux changements climatiques nous concerne tous. Ce projet a reçu un premier soutien financier de l’International Permafrost Association (IPA) en 2015, et depuis, plusieurs autres partenaires se sont joints à nous. C’est grâce à eux que nous présentons aujourd’hui cette version française. Nous y voilà, donc, trois ans après cette première idée. Ce que vous vous apprê-tez à lire est le résultat de nombreux échanges entre artistes et scientifiques. Nous avons d’abord lancé un appel d’offres et reçu 49 dossiers d’artistes pro-venant de 16 pays. Au terme d’une évaluation rigoureuse, nous avons choisi deux artistes pour travailler sur ce projet : Noémie Ross du Canada et Heta Nääs de Finlande. Avec l’apport des scientifiques, Noémie et Heta ont créé de fabuleuses illustrations expliquant les changements en cours dans les régions affectées par le pergélisol, comment ces mutations affectent les populations et les espèces, et ce que font les scientifiques pour mieux comprendre ces changements et aider les populations à s’y adapter. Nous souhaitons à tous beaucoup de plaisir à lire ce livret et nous en profitons pour remercier chaleureusement tous nos partenaires.

Beschreibung: Las fechas claves para la reunión científica del grupo de Paleomagnetismo de Iberia, MAGIBER X. (14, 15 y 16 de Septiembre de 2017, Valle del Grío, Provincia de Zaragoza) Desde sus inicios en el año 2001, el grupo de Paleomagnetismo de Iberia ha realizado reuniones de carácter periódico, generalmente bianuales. Estas reuniones se han caracterizado por su carácter familiar y cercano, en busca de la interacción positiva entre las personas que aúnan en sus estudios las ciencias de la tierra y el magnetismo, en todas sus disciplinas. Por ello, son bienvenidos trabajos de investigación en todas sus fases de desarrollo, ya sean trabajos finalizados o trabajos en estado de desarrollo que permitan la discusión entre los asistentes, e incluso puedan ayudar con sus sugerencias a la finalización de los mismos. También son recibidos otros trabajos que, si bien no totalmente relacionados, puedan permitir nuevas líneas de colaboración con otras disciplinas, pues si algo caracteriza al paleomagnetismo s.l. es su gran aplicabilidad en numerosos campos, diferentes entre sí.

Beschreibung: This thesis is devoted to an in-depth analysis of the ability of "Artificial Neural Networks" (ANN) to achieve reliable ground motion predictions. A first important aspect concerns the derivation of "GMPE" (Ground Motion Prediction Equations) with an ANN approach, and the comparison of their performance with those of "classical" GMGEs derived on the basis of empirical regressions with pre-established, more or less complex, functional forms. To perform such a comparison involving the two "betweeen-event" and "within-event" components of the random variability, we adapt the algorithm of the "random effects model" to the neural approach. This approach is tested on various, real and synthetic, datasets: the database compiled from European, Mediterranean and Middle Eastern events (RESORCE: Reference database for Seismic grOund-motion pRediction in Europe), the database NGA West 2 (Next Generation Attenuation West 2 developed in the USA), and the Japanese database derived from the KiK-net accelerometer network. In addition, a comprehensive set of synthetic data is also derived with a stochastic simulation approach. The considered ground motion parameters are those which are most used in earthquake engineering (PGA, PGV, response spectra and also, in some cases, local amplification functions). Such completely "data-driven" neural models, inform us about the respective, and possibly coupled, influences of the amplitude decay with distance, the magnitude scaling effects, and the site conditions, with a particular focus on the detection of non-linearities in site response. Another important aspect is the use of ANNs to test the relevance of different site proxies, through their ability to reduce the random variability of ground motion predictions. The ANN approach allows to use such site proxies either individually or combined, and to investigate their respective impact on the various characteristics of ground motion. The same section also includes an investigation on the links between the non-linear aspects of the site response and the different site proxies. Finally, the third section focuses on a few source-related effects: analysis of the influence of the "style of faulting" on ground motion, and, indirectly, the dependence between magnitude and seismic stress drop

Beschreibung: The IUGG Yearbook is a reference document of IUGG members, administrative officers, and Association and Union Commission officers that is updated annually and distributed free of charge. Each issue endeavors to update the contact information for hundreds of persons who are actively participating in IUGG scientific activities. Information is complied throughout the year until end December. The Yearbooks are published and posted at the IUGG webpage at the beginning of the year. The Yearbooks are printed together with the Annual Reports for the preceding year in May and mailed to National Committee for Geodesy and Geophysics, Adhering Bodies, IUGG partners, and major libraries.

Beschreibung: Comme premier résultat de son travail, le groupe ad hoc Open-Access-Gold présente cette prise de position. Il s’adresse à des institutions scientifiques qui sont impliquées dans divers aspects de la publication Open Access. Il structure et évalue les exigences dans les contrats basés sur le modèle auteur-payeur. De plus, il évoque les liens entre abonnement et Libre accès et émet des suggestions aux institutions concernées pour la mise en oeuvre de leurs stratégies en matière de Libre accès. L’objectif est d’établir, dans le domaine de la publication scientifique, de la transparence et de la pérennité selon les principes de la Science, et d’éviter la répétition de certaines dérives observées dans le passé.

Beschreibung: The chilean part of the subduction zone between the Nazca and South American plates is an ideal laboratory to understand the seismic and aseismic processes that take place on such a plate boundary. For instance, measuring the elastic deformation of the upper plate during the interseismic loading phase using GPS can help assessing the degree of locking between both plates. We calculate the kinematic coupling coefficient using a simple elastic modeling in which a backslip motion is applied on a buried dislocation in a semi-infinite elastic half-space. During this PhD, my aim was to obtain the coupling distribution along the entire chilean trench (18 ◦ S-38 ◦ S) and to compare it to seismotectonic segmentation of the megathrust. Therefore I collected all the previously published interseismic velocities and combined them into a single coherent data set. New data were also collected and processed since 2009 on new or renovated campaign networks. We obtain a new data set that covers almost all the subduction zone on more than ahundred benchmarks. Those data were used to map precisely the coupling distribution on the interface. Coupling strongly varies both along strike and along dip and draws a segmentation of the megathrust. The highly coupled segments correlate well with the rupture zones of historical megathrustearthquakes and intersegments, that are low coupled areas, correlate with zones that behave as barriers to the seismic propagation. Furthermore, intersegments often correlate with anomalies in the coastline (bays, peninsulas), subducting bathymetric features (ridges, fracture zones) and with a high-rate of moderate-magnitude subduction earthquakes. The Maule earthquake that occurred on February 27, 2010 ruptured a highly locked segment and stopped in low coupled intersegment areas. This earthquake gave us new insights on the relationship between apparent coupling coefficient and mechanical behavior of the subduction interface. Therefore, coupling maps should help estimating the seismic hazard along the Chilean subduction zone. In particular, we show here that the North Chile seismic gap is not formed of one single highly coupled segment and that it is cut in two by a large intersegment zone where coupling is low around Iquique. Finally, Loa, Paranal and Atacama highly coupled segments are identified as zones that may rupture alone with a Mw〉8 subduction earthquake, or with a megathrust earthquake in case of collective rupture, and where the seismic hazard is high. La zone de subduction entre les plaques Nazca et Amérique du Sud constitue, aux latitudesdu Chili, un laboratoire naturel d’exception pour étudier les processus qui permettent d’accommoder la convergence sur l’interface de subduction. En particulier, la mesure par GPS de la déformation de la plaque supérieure pendant la phase intersismique sur la subduction permet de quantifier l’intensité du blocage sur l’interface via le coefficient de couplage cinématique. Ce dernier peut être déterminé en utilisant un modèle de dislocation simple dans un milieu homogène élastique sur laquelle on applique la théorie du backslip. Cette thèse a pour objectif de déterminer la valeur de ce couplage intersismique au long de la subduction chilienne (18 ◦ S-38 ◦ S) et d’analyser ces variations en relation avec la segmentation sismotectonique et la sismicité historique. Pour cela, les vitesses intersismiques collectées au cours de ces 20 dernières années ont été combinées dans un même référentiel et de nouvelles données GPS ont été acquises sur des réseaux installés ou rénovés par les équipes franco-chiliennes depuis 2009. Cet effort instrumental associé au travail de traitement des données que j’ai réalisé conduit à un jeu de vitesses intersismiques sur plusieurs centaines de points et quasi continu sur la marge chilienne. Ces données ont été utilisées pour élaborer une cartographie précise du couplage au long de la subduction chilienne. La distribution de couplage qui est présentée dans ce manuscrit montre d’importantes variations latérales et en profondeur de la valeur du couplage et dessine ainsi une segmentation de la marge. Les segments fortement couplés semblent corrélés aux grandes ruptures historiques, tandis que les intersegments découplés semblent se comporter comme des barrières à leur propagation. Les zones d’intersegments correspondent à des zones atypiques de la subduction, souvent associées à des anomalies du trait de côte (baies, péninsules), à l’entrée en subduction de structures bathymétriques (rides, fractures) et à une sismicité de fond importante. Le séisme de Maule du 27 février 2010 (Mw 8.8) qui a rompu un segment fortement couplé et qui s’est arrêté dans des zones de faible couplage a permis de proposer un lien entre le couplage apparent et le comportement mécanique de l’interface.Sur la base de cette analyse, il semble possible d’utiliser les cartes de couplage intersismique pour mieux estimer l’aléa sismique au Chili. Dans ce travail, nous apportons notamment un éclairage nouveau sur la lacune du Grand Nord Chili en montrant que le segment couplé du Loaest nettement plus restreint que la lacune en elle-même et qu’un large intersegment découplé s’y développe autour d’Iquique. Une attention particulière est donc portée aux régions de l’Atacama, du Paranal et du Loa qui correspondent à des zones très fortement couplées, chacune susceptibles de produire un grand séisme de subduction potentiellement associé à un tsunami, et un séisme géant en cas de rupture collective.

Beschreibung: La zone de subduction entre les plaques Nazca et Amérique du Sud constitue, aux latitudesdu Chili, un laboratoire naturel d’exception pour étudier les processus qui permettent d’accommoder la convergence sur l’interface de subduction. En particulier, la mesure par GPS de la déformation de la plaque supérieure pendant la phase intersismique sur la subduction permet de quantifier l’intensité du blocage sur l’interface via le coefficient de couplage cinématique. Ce dernier peut être déterminé en utilisant un modèle de dislocation simple dans un milieu homogène élastique sur laquelle on applique la théorie du backslip. Cette thèse a pour objectif de déterminer la valeur de ce couplage intersismique au long de la subduction chilienne (18 ◦ S-38 ◦ S) et d’analyser ces variations en relation avec la segmentation sismotectonique et la sismicité historique. Pour cela, les vitesses intersismiques collectées au cours de ces 20 dernières années ont été combinées dans un même référentiel et de nouvelles données GPS ont été acquises sur des réseaux installés ou rénovés par les équipes franco-chiliennes depuis 2009. Cet effort instrumental associé au travail de traitement des données que j’ai réalisé conduit à un jeu de vitesses intersismiques sur plusieurs centaines de points et quasi continu sur la marge chilienne. Ces données ont été utilisées pour élaborer une cartographie précise du couplage au long de la subduction chilienne. La distribution de couplage qui est présentée dans ce manuscrit montre d’importantes variations latérales et en profondeur de la valeur du couplage et dessine ainsi une segmentation de la marge. Les segments fortement couplés semblent corrélés aux grandes ruptures historiques, tandis que les intersegments découplés semblent se comporter comme des barrières à leur propagation. Les zones d’intersegments correspondent à des zones atypiques de la subduction, souvent associées à des anomalies du trait de côte (baies, péninsules), à l’entrée en subduction de structures bathymétriques (rides, fractures) et à une sismicité de fond importante. Le séisme de Maule du 27 février 2010 (Mw 8.8) qui a rompu un segment fortement couplé et qui s’est arrêté dans des zones de faible couplage a permis de proposer un lien entre le couplage apparent et le comportement mécanique de l’interface. Sur la base de cette analyse, il semble possible d’utiliser les cartes de couplage intersismique pour mieux estimer l’aléa sismique au Chili. Dans ce travail, nous apportons notamment un éclairage nouveau sur la lacune du Grand Nord Chili en montrant que le segment couplé du Loa est nettement plus restreint que la lacune en elle-même et qu’un large intersegment découplé s’y développe autour d’Iquique. Une attention particulière est donc portée aux régions de l’Atacama, du Paranal et du Loa qui correspondent à des zones très fortement couplées, chacune susceptibles de produire un grand séisme de subduction potentiellement associé à un tsunami, et un séisme géant en cas de rupture collective.

Beschreibung: Protokolle der zu Rom vom 15. bis 24. Oktober 1883 abgehaltenen Sitzungen der Siebenten Allgemeinen Conferenz der Europäischen Gradmessung S. 3 Protokolle der permanenten Commission S. 111 General-Bericht über den Fortschritt der Arbeiten für die Europäische Gradmessung im Jahre 1883 - S. 223 Anhänge Verzeichnis der Tafeln