Geomática aplicada al análisis de riesgos geológicos

Tesis por compendio de publicaciones[ES]Esta Tesis Doctoral se ha realizado mediante el formato de compendio de artículos, con objetivos claramente diferenciados y concatenados entre sí con el fin de ampliar el conocimiento sobre la implementación de nuevas metodologías en Geomática Aplicada utilizando información de uso público para la gestión de la peligrosidad natural en la reducción del Riesgo Geológico. Se ha puesto énfasis en hacer conocer a la comunidad los beneficios de analizar los riesgos geológicos con anticipación para identificarlos espacialmente y establecer correcciones estructurales como criterio de prevención, lo que implica elaborar previamente mapas de zonas susceptibles a movimientos en masa, inundaciones, erosión hídrica, mapas sismo-tectónicos-volcánicos y de problemas geotécnicos, a partir de la Geomática Aplicada (Teledetección, Sistemas de Información Geográfica y Modelación Numérica) e información espacial georeferenciada. Se desarrollan en esta Tesis cinco métodos geomáticos aplicados a la reducción del riesgo geológico, validados mediante su aplicación en diferentes riesgos geológicos de varias regiones de Ecuador[EN][EN]This Doctoral Thesis has been carried out through the compendium format of articles, with clearly differentiated and concatenated objectives in order to expand knowledge on the implementation of new methodologies in Applied Geomatics using information of public use for the management of natural hazard in the reduction of Geological Risk. Emphasis has been placed on making the community aware of the benefits of analyzing geological risks in advance to spatially identify them and establish structural corrections as a prevention criterion, which implies preparing previously maps of areas susceptible to mass movements, floods, water erosion, Earthquake-tectonic-volcanic maps and geotechnical problems, from Applied Geomatics (Remote Sensing, Geographic Information Systems and Numerical Modeling) and georeferenced spatial information. Five geomatic methods applied to the reduction of geological risk are developed in this thesis, validated by their application to different geological risks in various regions of Ecuador

Impact of Etna’s volcanic emission on major ions and trace elements composition of the atmospheric deposition

Mt. Etna, on the eastern coast of Sicily (Italy), is one of the most active volcanoes on the planet and it is widely recognized as a big source of volcanic gases (e.g., CO2 and SO2), halogens, and a lot of trace elements, to the atmosphere in the Mediterranean region. Especially during eruptive periods, Etna’s emissions can be dispersed over long distances and cover wide areas. A group of trace elements has been recently brought to attention for their possible environmental and human health impacts, the Technology-critical elements. The current knowledge about their geochemical cycles is still scarce, nevertheless, recent studies (Brugnone et al., 2020) evidenced a contribution from the volcanic activity for some of them (Te, Tl, and REE). In 2021, in the framework of the research project “Pianeta Dinamico”, by INGV, a network of 10 bulk collectors was implemented to collect, monthly, atmospheric deposition samples. Four of these collectors are located on the flanks of Mt. Etna, other two are in the urban area of Catania and three are in the industrial area of Priolo, all most of the time downwind of the main craters. The last one, close to Cesarò (Nebrodi Regional Park), represents the regional background. The research aims to produce a database on major ions and trace element compositions of the bulk deposition and here we report the values of the main physical-chemical parameters and the deposition fluxes of major ions and trace elements from the first year of research. The pH ranged from 3.1 to 7.7, with a mean value of 5.6, in samples from the Etna area, while it ranged between 5.2 and 7.6, with a mean value of 6.4, in samples from the other study areas. The EC showed values ranging from 5 to 1032 μS cm-1, with a mean value of 65 μS cm-1. The most abundant ions were Cl- and SO42- for anions, Na+ and Ca+ for cations, whose mean deposition fluxes, considering all sampling sites, were 16.6, 6.8, 8.4, and 6.0 mg m-2 d, respectively. The highest deposition fluxes of volcanic refractory elements, such as Al, Fe, and Ti, were measured in the Etna’s sites, with mean values of 948, 464, and 34.3 μg m-2 d-1, respectively, higher than those detected in the other sampling sites, further away from the volcanic source (26.2, 12.4, 0.5 μg m-2 d-1, respectively). The same trend was also observed for volatile elements of prevailing volcanic origin, such as Tl (0.49 μg m-2 d-1), Te (0.07 μg m-2 d-1), As (0.95 μg m-2 d-1), Se (1.92 μg m-2 d-1), and Cd (0.39 μg m-2 d-1). Our preliminary results show that, close to a volcanic area, volcanic emissions must be considered among the major contributors of ions and trace elements to the atmosphere. Their deposition may significantly impact the pedosphere, hydrosphere, and biosphere and directly or indirectly human health

Impact of geogenic degassing on C-isotopic composition of dissolved carbon in karst systems of Greece

The Earth C-cycle is complex, where endogenic and exogenic sources are interconnected, operating in a multiple spatial and temporal scale (Lee et al., 2019). Non-volcanic CO2 degassing from active tectonic structures is one of the less defined components of this cycle (Frondini et al., 2019). Carbon mass-balance (Chiodini et al., 2000) is a useful tool to quantify the geogenic carbon output from regional karst hydrosystems. This approach has been demonstrated for central Italy and may be valid also for Greece, due to the similar geodynamic settings. Deep degassing in Greece has been ascertained mainly at hydrothermal and volcanic areas, but the impact of geogenic CO2 released by active tectonic areas has not yet been quantified. The main aim of this research is to investigate the possible deep degassing through the big karst aquifers of Greece. Since 2016, 156 karst springs were sampled along most of the Greek territory. To discriminate the sources of carbon, the analysis of the isotopic composition of carbon was carried out. δ13CTDIC values vary from -16.61 to -0.91‰ and can be subdivided into two groups characterized by (a) low δ13CTDIC, and (b) intermediate to high δ13CTDIC with a threshold value of -6.55‰. The composition of the first group can be related to the mixing of organic-derived CO2 and the dissolution of marine carbonates. Springs of the second group, mostly located close to Quaternary volcanic areas, are linked to possible carbon input from deep sources

EVOLUTION OF THE SUBCONTINENTAL LITHOSPHERE DURING MESOZOIC TETHYAN RIFTING: CONSTRAINTS FROM THE EXTERNAL LIGURIAN MANTLE SECTION (NORTHERN APENNINE, ITALY)

Our study is focussed on mantle bodies from the External Ligurian ophiolites, within the Monte Gavi and Monte Sant'Agostino areas. Here, two distinct pyroxenite-bearing mantle sections were recognized, mainly based on their plagioclase-facies evolution. The Monte Gavi mantle section is nearly undeformed and records reactive melt infiltration under plagioclase-facies conditions. This process involved both peridotites (clinopyroxene-poor lherzolites) and enclosed spinel pyroxenite layers, and occurred at 0.7–0.8 GPa. In the Monte Gavi peridotites and pyroxenites, the spinel-facies clinopyroxene was replaced by Ca-rich plagioclase and new orthopyroxene, typically associated with secondary clinopyroxene. The reactive melt migration caused increase of TiO2 contents in relict clinopyroxene and spinel, with the latter also recording a Cr2O3 increase. In the Monte Gavi peridotites and pyroxenites, geothermometers based on slowly diffusing elements (REE and Y) record high temperature conditions (1200-1250 °C) related to the melt infiltration event, followed by subsolidus cooling until ca. 900°C. The Monte Sant'Agostino mantle section is characterized by widespread ductile shearing with no evidence of melt infiltration. The deformation recorded by the Monte Sant'Agostino peridotites (clinopyroxene-rich lherzolites) occurred at 750–800 °C and 0.3–0.6 GPa, leading to protomylonitic to ultramylonitic textures with extreme grain size reduction (10–50 μm). Compared to the peridotites, the enclosed pyroxenite layers gave higher temperature-pressure estimates for the plagioclase-facies re-equilibration (870–930 °C and 0.8–0.9 GPa). We propose that the earlier plagioclase crystallization in the pyroxenites enhanced strain localization and formation of mylonite shear zones in the entire mantle section. We subdivide the subcontinental mantle section from the External Ligurian ophiolites into three distinct domains, developed in response to the rifting evolution that ultimately formed a Middle Jurassic ocean-continent transition: (1) a spinel tectonite domain, characterized by subsolidus static formation of plagioclase, i.e. the Suvero mantle section (Hidas et al., 2020), (2) a plagioclase mylonite domain experiencing melt-absent deformation and (3) a nearly undeformed domain that underwent reactive melt infiltration under plagioclase-facies conditions, exemplified by the the Monte Sant'Agostino and the Monte Gavi mantle sections, respectively. We relate mantle domains (1) and (2) to a rifting-driven uplift in the late Triassic accommodated by large-scale shear zones consisting of anhydrous plagioclase mylonites. Hidas K., Borghini G., Tommasi A., Zanetti A. & Rampone E. 2021. Interplay between melt infiltration and deformation in the deep lithospheric mantle (External Liguride ophiolite, North Italy). Lithos 380-381, 105855

Land Surface Monitoring Based on Satellite Imagery

This book focuses attention on significant novel approaches developed to monitor land surface by exploiting satellite data in the infrared and visible ranges. Unlike in situ measurements, satellite data provide global coverage and higher temporal resolution, with very accurate retrievals of land parameters. This is fundamental in the study of climate change and global warming. The authors offer an overview of different methodologies to retrieve land surface parameters— evapotranspiration, emissivity contrast and water deficit indices, land subsidence, leaf area index, vegetation height, and crop coefficient—all of which play a significant role in the study of land cover, land use, monitoring of vegetation and soil water stress, as well as early warning and detection of forest fires and drought

Semantic location extraction from crowdsourced data

Crowdsourced Data (CSD) has recently received increased attention in many application areas including disaster management. Convenience of production and use, data currency and abundancy are some of the key reasons for attracting this high interest. Conversely, quality issues like incompleteness, credibility and relevancy prevent the direct use of such data in important applications like disaster management. Moreover, location information availability of CSD is problematic as it remains very low in many crowd sourced platforms such as Twitter. Also, this recorded location is mostly related to the mobile device or user location and often does not represent the event location. In CSD, event location is discussed descriptively in the comments in addition to the recorded location (which is generated by means of mobile device's GPS or mobile communication network). This study attempts to semantically extract the CSD location information with the help of an ontological Gazetteer and other available resources. 2011 Queensland flood tweets and Ushahidi Crowd Map data were semantically analysed to extract the location information with the support of Queensland Gazetteer which is converted to an ontological gazetteer and a global gazetteer. Some preliminary results show that the use of ontologies and semantics can improve the accuracy of place name identification of CSD and the process of location information extraction

Spectral induced polarisation for an enhanced pore-space characterisation and analysis of dissolution processes of carbonate rocks

Subrosion, d.h. die unterirdische Auslaugung von leicht löslichen Gesteinen wie z.B. Karbonat, ist eine weltweit auftretende Erscheinung, die letztlich zu subrosionsbedingten Erdfällen und Senken führt. Grundlagenforschung im Bereich von Lösungsprozessen an Karbonaten ist erforderlich für ein besseres Prozessverständnis dieser Ereignisse, um die Risikoeinschätzung sowie die Vorhersagemöglichkeiten zu verbessern. Diese Dissertation befasst sich mit der erweiterten Porenraumcharakterisierung und Auswertung mittels Spektraler induzierter Polarisation (SIP) von Lösungsprozessen in Karbonaten. SIP ist eine etablierte Methode für die Durchführung von Grundlagenforschung auf Porenskala im Bereich der Porenraumcharakterisierung und Bestimmung von Gesteinseigenschaften. Systematische Labormessungen an Karbonaten werden durchgeführt, um Gesteinscharakteristika und deren Einfluss auf die IP-Parameter als auch ihre Sensitivität auf Lösungsprozesse zu untersuchen. Die gesteinsspezifischen Untersuchungen umfassen ein multimethodisches Herangehen, welches petrophysikalische, mineralogische und geochemische Verfahren kombiniert, u.a. Spektren der komplexen elektrischen Leitfähigkeit und Daten von 2D und 3D Bildgebungsverfahren als auch Messgrößen wie Porosität, Permeabilität, spezifische Oberfläche und Verteilungen der Nuklear-Magnetischer Resonanz Relaxationszeiten. Zuerst werden für ein besseres Verständnis der IP-Parameter sowie Polarisationsmechanismen in Karbonaten Probensätze vier verschiedener Typlokationen mit einer großen Variation ihrer petrophysikalischen Eigenschaften untersucht. Zur Untersuchung des Polarisationsverhaltens der Karbonatproben werden verschiedene IP-Experimente durchgeführt und die Ergebnisse mit den vorhandenen Erkenntnissen über Sandsteine verglichen. Vier verschiedene Typen des Polarisationsverhalten können im Phasenspektrum ermittelt werden: (1) ein konstanter Phasenwinkel, (2) ein kontinuierlicher Phasenanstieg, (3) eine Kombinaten aus beiden sowie (4) ein Maximumtyp. Die explizite Zuordnung eines Karbonattyps zu einem charakteristischen Kurventyp ist übertragbar für den gesamten Probensatz. Der Vergleich von IP-Parametern mit petrophysikalischen Daten zeigt, dass es anspruchsvoller ist klare Korrelationen zwischen den Parametern festzustellen, vor allem im Vergleich zu Sandsteinen. Die Übertragbarkeit von empirischen Beziehungen und Modellannahmen, wie z.B. Formationsfaktorabschätzung und Permeabilitätsvorhersage, ist dennoch realisierbar. Im zweiten Schritt wurde ein Messplatz für systematische Lösungen sowie ein maßgeschneidertes experimentelles Konzept erfolgreich konzipiert und angewendet, um den Einfluss von Lösungsprozessen auf Mineral- und Porenstrukturen unter kontrollierten Laborbedingungen zu untersuchen. Zur systematischen Erfassung der Änderungen im Porenraum wurden vor und nach jeder Lösung gesteinsspezifische Untersuchen vorgenommen. Der Lösungsprozess beeinflusst verschiedene petrophysikalische Parameter mit unterschiedlicher Ausprägung. Während die Korndichte und Porosität zunehmen, erhöht sich zunächst die spezifische Oberfläche und verringert sich in späteren Stufen. Die Porenradienverteilungen aus Quecksilberporosimetrie und μ-CT Daten weisen auf eine Vergrößerung des dominanten Porenradius mit zunehmenden Lösungstufen hin. Die durch die Lösungsprozesse hervorgerufenen Änderungen in den Karbonaten lassen sich bis zu einem gewissen Grad mit SIP beobachten. Der Anstieg im Realteil der elektrischen Leitfähigkeit ergibt sich aus der zunehmenden Porosität sowie dem abnehmenden Formationsfaktor und der abnehmenden Volumentortuosität. Die Form der 00-Spektren ändert sich ebenfalls, da bei höheren Frequenzen der Imaginärteil der elektrischen Leitfähigkeit zunimmt, was auf die Entstehung kleinerer Poren hindeutet. Die gegensätzlichen Prozesse Glättung und Aufrauung der Porenoberflächen haben eine Abnahme bzw. Zunahme der Oberflächentortuosität zur Folge, was dementsprechend das Verhalten des Imaginärteils der elektrischen Leitfähigkeit beeinflusst. Insgesamt nimmt die Volumenleitfähigkeit stärker zu als die Oberflächenleitfähigkeit. Aufgrund der durch die Lösungsprozesse verursachten kleinen Änderungen der Gesteinsparameter ist die Dateninterpretation herausfordernd. Daher ist weitere Forschung im Bereich von Lösungsprozessen an Karbonaten erforderlich. Diese Dissertation verdeutlicht das Potential von SIP zur erweiterten Porenraumcharakterisierung sowie Auswertung von Lösungsprozessen von Karbonaten.Subrosion due to the subsurface leaching of soluble rocks, e.g. carbonates, is a global phenomenon that results in surface depressions and sinkholes. Fundamental research on dissolution processes of carbonates is necessary to better understand subrosion processes, to improve risk assessment and forecasting. This thesis deals with enhanced pore-space characterisation and analysis of dissolution processes in carbonates using spectral induced polarisation (SIP). SIP is a suitable method to conduct fundamental research to characterise the pore space and to obtain detailed information on rock properties. Systematic laboratory measurements on carbonates are conducted to investigate rock characteristics and their influence on IP responses and their sensitivity to dissolution processes. The core analysis program includes a multi-methodical approach that combines petrophysical, mineralogical and geochemical techniques, e.g. complex conductivity spectra, and data from 2D and 3D imaging techniques, as well as quantities such as porosity, permeability, specific surface area, and nuclear magnetic-resonance decay-time distributions. First, carbonate sample sets from four different type locations with a broad range of petrophysical parameters are investigated to better understand IP responses and mechanisms in carbonates. Different IP experiments are conducted to investigate the polarisation behaviour of the carbonate samples and the results are compared with the existing knowledge of SIP on sandstones. I show that four different types of polarisation behaviour can be observed in the spectra of the phase shift: (1) a constant phase angle, (2) a continuous increase, (3) a combination of both, and (4) a maximum type. Each carbonate type can be assigned to a characteristic curve type, which is reproducible for the whole sample set. Comparison of SIP with petrophysical parameters shows that it is more challenging to find clear correlations, especially compared to sandstones. However, it is possible to transfer empirical relationships and model assumptions from sandstones to carbonates, e.g. formation factor estimation and permeability prediction. In the second step, an experimental setup for systematic dissolution under monitoring conditions and an uniquely tailored experimental concept was successfully developed to investigate the impact of dissolution procedures on mineral and pore structure under controlled conditions. Before and after each dissolution step, the core analysis program was carried out to systematically record the changes of pore space. Dissolution processes change distinct petrophysical parameters on different scales. Grain density and porosity increase, whereas the specific surface increases at first and decreases at later stages, depending on contrary scenarios of specific surface variation on pore scale. The pore radii distributions of mercury intrusion porosimetry and μ-CT data reveal an enlargement of the dominant pore radii with increasing dissolution. Changes within the carbonate due to dissolution can be observed by SIP to a certain extent. An increased porosity, a decreased formation factor, and a decreased volume tortuosity leads to an increased real part of electrical conductivity. The shape of the 00-spectra changes as well. The imaginary part of electrical conductivity increases for higher frequencies due to dissolution processes, which indicates the formation of smaller pores. Contradictory processes of smoothing and roughing of the pore surface leads to both decreased and increased surface tortuosities, which affects the behaviour of the imaginary part of conductivity during dissolution. In summary, the volume conductivity increases more strongly than the surface conductivity. Due to small, dissolution-induced changes of the rock parameters, data interpretation is challenging. Hence, further research regarding dissolution processes of carbonates is required. This work demonstrates the potential of enhanced pore-space characterisation and analysis of dissolution processes of carbonate rocks using SIP