1,086 research outputs found

    In situ estimation of ice crystal properties at the South Pole using LED calibration data from the IceCube Neutrino Observatory

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    The IceCube Neutrino Observatory instruments about 1 km3 of deep, glacial ice at the geographic South Pole. It uses 5160 photomultipliers to detect Cherenkov light emitted by charged relativistic particles. An unexpected light propagation effect observed by the experiment is an anisotropic attenuation, which is aligned with the local flow direction of the ice. We examine birefringent light propagation through the polycrystalline ice microstructure as a possible explanation for this effect. The predictions of a first-principles model developed for this purpose, in particular curved light trajectories resulting from asymmetric diffusion, provide a qualitatively good match to the main features of the data. This in turn allows us to deduce ice crystal properties. Since the wavelength of the detected light is short compared to the crystal size, these crystal properties include not only the crystal orientation fabric, but also the average crystal size and shape, as a function of depth. By adding small empirical corrections to this first-principles model, a quantitatively accurate description of the optical properties of the IceCube glacial ice is obtained. In this paper, we present the experimental signature of ice optical anisotropy observed in IceCube light-emitting diode (LED) calibration data, the theory and parameterization of the birefringence effect, the fitting procedures of these parameterizations to experimental data, and the inferred crystal properties.</p

    Advances and Applications of DSmT for Information Fusion. Collected Works, Volume 5

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    This fifth volume on Advances and Applications of DSmT for Information Fusion collects theoretical and applied contributions of researchers working in different fields of applications and in mathematics, and is available in open-access. The collected contributions of this volume have either been published or presented after disseminating the fourth volume in 2015 in international conferences, seminars, workshops and journals, or they are new. The contributions of each part of this volume are chronologically ordered. First Part of this book presents some theoretical advances on DSmT, dealing mainly with modified Proportional Conflict Redistribution Rules (PCR) of combination with degree of intersection, coarsening techniques, interval calculus for PCR thanks to set inversion via interval analysis (SIVIA), rough set classifiers, canonical decomposition of dichotomous belief functions, fast PCR fusion, fast inter-criteria analysis with PCR, and improved PCR5 and PCR6 rules preserving the (quasi-)neutrality of (quasi-)vacuous belief assignment in the fusion of sources of evidence with their Matlab codes. Because more applications of DSmT have emerged in the past years since the apparition of the fourth book of DSmT in 2015, the second part of this volume is about selected applications of DSmT mainly in building change detection, object recognition, quality of data association in tracking, perception in robotics, risk assessment for torrent protection and multi-criteria decision-making, multi-modal image fusion, coarsening techniques, recommender system, levee characterization and assessment, human heading perception, trust assessment, robotics, biometrics, failure detection, GPS systems, inter-criteria analysis, group decision, human activity recognition, storm prediction, data association for autonomous vehicles, identification of maritime vessels, fusion of support vector machines (SVM), Silx-Furtif RUST code library for information fusion including PCR rules, and network for ship classification. Finally, the third part presents interesting contributions related to belief functions in general published or presented along the years since 2015. These contributions are related with decision-making under uncertainty, belief approximations, probability transformations, new distances between belief functions, non-classical multi-criteria decision-making problems with belief functions, generalization of Bayes theorem, image processing, data association, entropy and cross-entropy measures, fuzzy evidence numbers, negator of belief mass, human activity recognition, information fusion for breast cancer therapy, imbalanced data classification, and hybrid techniques mixing deep learning with belief functions as well

    Integrated Geophysical Analysis of Passive Continental Margins: Insights into the Crustal Structure of the Namibian Margin from Magnetotelluric, Gravity, and Seismic Data

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    Passive continental margin research amalgamates the investigation of many broad topics, such as the emergence of oceanic crust, lithospheric stress patterns and plume-lithosphere interaction, reservoir potential, methane cycle, and general global geodynamics. Central tasks in this field of research are geophysical investigations of the structure, composition, and dynamic of the passive margin crust and upper mantle. A key practice to improve geophysical models and their interpretation, is the integrated analysis of multiple data, or the integration of complementary models and data. In this thesis, I compare four different inversion results based on data from the Namibian passive continental margin. These are a) a single method MT inversion; b) constrained inversion of MT data, cross-gradient coupled with a fixed structural density model; c) cross-gradient coupled joint inversion of MT and satellite gravity data; d) constrained inversion of MT data, cross-gradient coupled with a fixed gradient velocity model. To bridge the formal analysis of geophysical models with geological interpretations, I define a link between the physical parameter models and geological units. Therefore, the results from the joint MT and gravity inversion (c) are correlated through a user-unbiased clustering analysis. This clustering analysis results in a distinct difference in the signature of the transitional crust south of- and along the supposed hot-spot track Walvis Ridge. I ascribe this contrast to an increase in magmatic activity above the volcanic center along Walvis Ridge. Furthermore, the analysis helps to clearly identify areas of interlayered massive, and weathered volcanic flows, which are usually only identified in reflection seismic studies as seaward dipping reflectors. Lastly, the clustering helps to differentiate two types of sediment cover. Namely, one of near-shore, thick, clastic sediments, and one of further offshore located, more biogenic, marine sediments

    The Rapid Acquisition and Application of Geophysical Data to the Sustainable and Proficient Management of Shallow Aquifers and Cemeteries

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    Rapidly acquired non-invasive geophysical data is key to reducing the risk inherent in subsurface investigations. It achieves this risk reduction by provision of spatiotemporally dense datasets and new methods to measure the efficacy of acquisition, analysis, and modeling. In a first example, I use two geophysical methods—electrical resistivity tomography and time-domain electromagnetics—to investigate the subsurface in a rapidly urbanizing alluvial floodplain setting. Specifically I focus on the geologic structure of a shallow alluvial aquifer in the Brazos River floodplain of Texas, characterizing dynamic hydrological interactions between the aquifer and the adjacent river. Based on new geophysical insights, I determine how the sedimentary architecture of the shallow alluvial aquifer acts as a control on its recharge and discharge and how bidirectional preferential flow pathways establish hydrologic communication between the aquifer and the river at human and geologic time scales. In a second example, I develop a protocol to improve identification of unmarked graves in a historic African-American cemetery. I show that a geophysicist’s detection proficiency, expressed in terms of true-positive, true-negative, false-positive, and false-negative percentages, can be improved using radar signatures of nearby known targets as a proxy for ground-truth

    Fallas activas de la cordillera Ibérica Centro-Oriental

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    Las fallas extensionales recientes de la Cordillera Ibérica centro-oriental limitan o cortan las cuencas neógeno-cuaternarias de Calatayud, Jiloca, Teruel, llegando hasta las fosas del Maestrat. Son las denominadas fallas de Río Grío-Pancrudo, Munébrega, Daroca, Calamocha, Sierra Palomera, Concud, Teruel, Valdecebro, El Pobo, Peralejos-Tortajada-Cabigordo, La Hita y Maestrat. Todas ellas han registrado desplazamientos de escala deca- a hectométrica desde el Plioceno superior, y muchas muestran evidencias de actividad en el Pleistoceno, lo que obliga a tener en cuenta sus correspondientes potenciales sismogénicos. Son el resultado de la inversión negativa de estructuras variscas previas, reactivadas durante la compresión alpina en el Paleógeno y finalmente invertidas en la extensión Neógeno-Cuaternaria. En la actualidad, esta extensión está representada por un campo de esfuerzos radial con una dirección de extensión preferente ENE-WSW. En esta tesis se integra la información disponible en la literatura sobre muchas de estas fallas, que ya habían sido caracterizadas por autores previos, con el estudio en profundidad de las fallas de Río Grío-Pancrudo, Calamocha y Sierra Palomera. Todas ellas han sido investigadas usando métodos estructurales, morfotectónicos y paleosismológicos, y se ha caracterizado su geometría, direcciones de transporte, tasas de deslizamiento y potencial sismogénico. Para el estudio morfotectónico se usa la Superficie de Erosión Fundamental o SEF (3,8¿3,5 Ma) como marcador de la deformación.La falla de Río Grío-Pancrudo es una macroestructura extensional que forma parcialmente el borde noreste de la cuenca de Calatayud, extendiéndose hasta 95 km de longitud, y rehundiendo su relleno mio-plioceno. Su dirección media es NNW-SSE y está dividida en dos segmentos dispuestos en relevo diestro (Río Grío-Lanzuela y Cucalón-Pancrudo). Su actividad extensional ha generado un basculamiento de rollover en su bloque superior, desplazamiento de la SEF, escarpes morfológicos, reversión del drenaje (en el valle del Río Güeimil) y rupturas superficiales en sedimentos del Plioceno superior-Cuaternario. El salto neto máximo de la SEF es de 305-325 m, con una tasa neta a largo plazo de 0,09 mm/a en 3,5 Ma. También produce un salto neto de 155-235 m en los últimos 2 Ma, con una tasa neta de 0,07-0,11 mm/a, y de hasta ca. 22 m en 66 ka, implicando una tasa neta de 0,30-0,36 mm/a. El estudio de una trinchera excavada en el segmento de falla de Cucalón-Pancrudo ha permitido interpretar dos eventos, y un posible tercer evento adicional incierto, comprendidos entre 18 y 3 ka. El salto neto total registrado en la trinchera es de 1,1 m, e implica una tasa neta en este sector de la falla de 0,07-0,08 mm/a para los últimos 18 ka.La falla de Calamocha es una falla normal de 18 km de longitud con dirección NNW-SSE. Desplaza el sector norte de la fosa del Jiloca respecto al sector sur de la cuenca de Calatayud, con un salto neto máximo de la SEF de 190¿230 m y una tasa neta a largo plazo de 0,05¿0,06 mm/a en 3,5 Ma. El estudio paleosismológico evidencia su actividad durante el Pleistoceno superior, con cuatro eventos ocurridos entre 125 y 70 ka, un posible evento anterior a ellos datado en 140 ka y un último evento al que se le asocia una edad de 14 ka. Su tasa neta a corto plazo es de 0,10 mm/a para los últimos 70 ka.La falla de Sierra Palomera también limita la fosa del Jiloca por el este, con dirección NNW-SSE uniforme a lo largo de sus 26 km de longitud. Desplaza la SEF hasta ca. 330, y hasta aprox. 480 m cuando se incluye la componente de bending de su bloque superior, con unas tasas a largo plazo de 0,09-0,10 y 0,13-0,15 mm/a, respectivamente. Una falla antitética a la principal muestra evidencias de actividad durante el Pleistoceno medio-superior, desplazando hasta 2,5 m la superficie de un abanico aluvial. En esa misma falla, una trinchera excavada ha permitido inferir hasta siete eventos, cuya edad no ha podido ser precisada, aunque sí podría acotarse el último evento a una edad de 50 ka. Su análisis retrodeformacional sugiere que los patrones de fracturación han pasado de ser dominantemente sintéticos a antitéticos con la principal, lo que sugiere un cambio de mayor control cinemático de la estructura en rollover a un mayor control dinámico del campo de esfuerzos.Las demás fallas recientes de la Cordillera Ibérica centro-oriental tienen dirección cercana a NW-SE y NNW-SSE, y se encuentran en los márgenes de la cuenca de Calatayud (Munébrega-Gallocanta, Daroca) y la fosa del Jiloca (Concud), así como en la cuenca de Teruel (fallas de la Sierra de El Pobo, Peralejos, Cabigordo, Tortajada, Teruel, La Hita). Con carácter más local, aparecen otras fallas de dirección próxima a E-W (Valdecebro). En el sector oriental de la cadena se extiende el sistema de fosas del Maestrat, de dirección NNE-SSW. Son fallas con longitudes del orden de 10^1 km que desplazan la SEF con saltos máximos del orden de 10^2 m durante el Plioceno superior-Cuaternario, arrojando tasas netas de movimiento a largo plazo de entre 0,05 y 0,15 mm/a (media: 0,08 mm/a; últimos 3,8-3,5 Ma). La mayoría de las fallas también evidencian actividad recurrente durante el Cuaternario. En el sector central, a excepción de las fallas de Daroca y Munébrega-Gallocanta, las tasas a corto plazo (0,05¿0,36 mm/a; media: 0,21 mm/a; Pleistoceno superior) son superiores a las promediadas a largo plazo. Esto contrasta con lo que ocurre en el sector oriental, donde trabajos previos muestran cómo su actividad tiende a disminuir durante el Cuaternario.Integrando esos resultados, se propone un modelo de deformación global de la corteza de la región, en el que el campo de esfuerzos actual es heterogéneo en el espacio y en el tiempo, y refleja la combinación de varios mecanismos geodinámicos que se solapan en la región: (1) la extensión WNW-ESE ligada al rifting en el surco de Valencia, que es dominante en el sector más oriental de la cadena (sobre todo durante el Mio-Plioceno); (2) el proceso de abombamiento o doming cortical que afecta a la Cordillera Ibérica centro-oriental (desde el Plio-Cuaternario), que induce el campo de extensión radial y probablemente intensifica la actividad de las fallas en el sector central (durante el Cuaternario); y (3) la compresión intraplaca NNW-SSE relacionada con el empuje de la Placa Africana, que determina la orientación dominante de las trayectorias de SHmax y SHmin en el sector central de la cadena y favorece la activación de las fallas longitudinales. La propagación del rifting hacia el interior de Iberia y el influjo creciente del doming a lo largo del Plioceno-Cuaternario pueden explicar la aceleración registrada en el movimiento en las fallas principales de Teruel, y su atenuación en las fallas del margen del Surco de Valencia. <br /

    Coupled surface to deep Earth processes: Perspectives from TOPO-EUROPE with an emphasis on climate- and energy-related societal challenges

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    Understanding the interactions between surface and deep Earth processes is important for research in many diverse scientific areas including climate, environment, energy, georesources and biosphere. The TOPO-EUROPE initiative of the International Lithosphere Program serves as a pan-European platform for integrated surface and deep Earth sciences, synergizing observational studies of the Earth structure and fluxes on all spatial and temporal scales with modelling of Earth processes. This review provides a survey of scientific developments in our quantitative understanding of coupled surface-deep Earth processes achieved through TOPO-EUROPE. The most notable innovations include (1) a process-based understanding of the connection of upper mantle dynamics and absolute plate motion frames; (2) integrated models for sediment source-to-sink dynamics, demonstrating the importance of mass transfer from mountains to basins and from basin to basin; (3) demonstration of the key role of polyphase evolution of sedimentary basins, the impact of pre-rift and pre-orogenic structures, and the evolution of subsequent lithosphere and landscape dynamics; (4) improved conceptual understanding of the temporal evolution from back-arc extension to tectonic inversion and onset of subduction; (5) models to explain the integrated strength of Europe's lithosphere; (6) concepts governing the interplay between thermal upper mantle processes and stress-induced intraplate deformation; (7) constraints on the record of vertical motions from high-resolution data sets obtained from geo-thermochronology for Europe's topographic evolution; (8) recognition and quantifications of the forcing by erosional and/or glacial-interglacial surface mass transfer on the regional magmatism, with major implications for our understanding of the carbon cycle on geological timescales and the emerging field of biogeodynamics; and (9) the transfer of insights obtained on the coupling of deep Earth and surface processes to the domain of geothermal energy exploration. Concerning the future research agenda of TOPO-EUROPE, we also discuss the rich potential for further advances, multidisciplinary research and community building across many scientific frontiers, including research on the biosphere, climate and energy. These will focus on obtaining a better insight into the initiation and evolution of subduction systems, the role of mantle plumes in continental rifting and (super)continent break-up, and the deformation and tectonic reactivation of cratons; the interaction between geodynamic, surface and climate processes, such as interactions between glaciation, sea level change and deep Earth processes; the sensitivity, tipping points, and spatio-temporal evolution of the interactions between climate and tectonics as well as the role of rock melting and outgassing in affecting such interactions; the emerging field of biogeodynamics, that is the impact of coupled deep Earth – surface processes on the evolution of life on Earth; and tightening the connection between societal challenges regarding renewable georesources, climate change, natural geohazards, and novel process-understanding of the Earth system

    Advances in Methane Production from Coal, Shale and Other Tight Rocks

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    This collection reports on the state of the art in fundamental discipline application in hydrocarbon production and associated challenges in geoengineering activities. Zheng et al. (2022) report an NMR-based method for multiphase methane characterization in coals. Wang et al. (2022) studied the genesis of bedding fractures in Ordovician to Silurian marine shale in the Sichuan basin. Kang et al. (2022) proposed research focusing on the prediction of shale gas production from horizontal wells. Liang et al. (2022) studied the pore structure of marine shale by adsorption method in terms of molecular interaction. Zhang et al. (2022) focus on the coal measures sandstones in the Xishanyao Formation, southern Junggar Basin, and the sandstone diagenetic characteristics are fully revealed. Yao et al. (2022) report the source-to-sink system in the Ledong submarine channel and the Dongfang submarine fan in the Yinggehai Basin, South China Sea. There are four papers focusing on the technologies associated with hydrocarbon productions. Wang et al. (2022) reported the analysis of pre-stack inversion in a carbonate karst reservoir. Chen et al. (2022) conducted an inversion study on the parameters of cascade coexisting gas-bearing reservoirs in coal measures in Huainan. To ensure the safety CCS, Zhang et al (2022) report their analysis of available conditions for InSAR surface deformation monitoring. Additionally, to ensure production safety in coal mines, Zhang et al. (2022) report the properties and application of gel materials for coal gangue control

    Synthesis of Shoreline, Sea Level Rise, and Marsh Migration Data for Wetland Restoration Targeting Final Report

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    Coastal marsh loss is a significant issue globally, due in part to rising sea levels and high levels of coastal human activity. Marshes have natural mechanisms to allow them to adapt to rising sea levels, however, migration across the landscape is one of those mechanisms and is frequently in conflict with human use of the shoreline. Ensuring the persistence of marshes into the future requires an understanding of where marshes are likely to migrate under sea level rise and targeting those areas for conservation and preservation activities. The goal of this project was to 1) compile existing datasets and information related to marsh migration under sea level rise-driven inundation due to forecasted climate change, topography of bay shorelines, shoreline condition (e.g., erosion rates, hardening, existing natural resources), existing wetland area and potential migration corridors, and other relevant data from around the Chesapeake Bay and 2) develop a methodology that synthesizes the information in a format that can be used to assist with marsh conservation and restoration decisions under multiple sea level rise scenarios (see associated report). This dataset is the resulting data from the methodology development

    Abstracts of the 1st GeoDays, 14th–17th March 2023, Helsinki, Finland

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