x, 57 p. : ill. (mostly col.) / An extensive area west of the Three Sisters volcanoes of Oregon has been actively uplifting for over a decade. Examining the deformation is imperative to improve understanding of the potential hazards of Cascade volcanism and the emplacement of magma. I refine the timing of the onset of the deformation, resolve the change in uplift rates through time, and quantify the current deformation rate using Interferometric Synthetic Aperture Radar. The deformation is assessed in time and space using single interferogram InSAR, stacks of interferograms, and line-of-sight time series. I examine the shape of the deformation pattern and explore volcanic source parameters using a Mogi model and tension crack model with topographic corrections. By using the best fit model and combining all useable interferograms from different tracks, I create the first complete continuous inflation time series of the Three Sisters volcanic uplift from 1992 to 2010. / Committee in charge: Dr. David A. Schmidt, Chair; Dr. Katharine V. Cashman, Member; Dr. Joshua J. Roering, Member

Plains volcanism in Tharsis region on Mars: Ages and Rheology of Eruption Products Remote sensing data show clusters of low shield volcanoes in Tharsis volcanic province on Mars (Hauber et al., 2009). These low shield volcanoes and associated landforms are comparable with terrestrial plain-style volcanic products (Plescia, 1981) as defined by Greeley (1982) in the Snake River Plain in Idaho, which represents an intermediate style of volcanic activity ranging between flood basalts and the Hawaiian shields. While a number of recent studies addressed some aspects of low shield volcanoes, in particular their morphology, morphometry, and lava rheology, no systematic study including the chronology for the entire region of Tharsis is available so far. The goal of this work is to determine relative and absolute ages of low shield volcanoes and surrounding lava flows and their basic rheological properties. We used crater size-frequency distribution method (CSFD) developed by Hartman and Neukum (2001) and Ivanov (2001) for determination of absolute dating of the surface. For calculation of the rheological properties of the lava, we used methods established by Hiesinger et al. (2007). It is known that the low shield volcanoes on Mars consist of basaltic lavas that had low viscosities during their effusion, which can...

L'évolution de la majorité des volcans basaltiques est marquée par des phénomènes récurrents d'instabilité latérale. De nombreux facteurs d'instabilité, impliqués dans des déstabilisations à long terme ou des effondrements de flancs instantanés, ont été recensés depuis l'événement majeur qui a frappé le Mont Saint-Helens en 1980. Cependant, le rôle de ces facteurs sur la stabilité mécanique des édifices est mal contraint dans la mesure où les glissements de flancs résultent en général de plusieurs causes simultanées. Notre étude se concentre sur une comparaison des caractéristiques morphologiques et structurales de deux systèmes basaltiques, La Réunion (Océan Indien, France) et Stromboli (Mer Tyrrhénienne, Italie). Nous avons montré que, bien qu'ayant des volumes et des contextes géodynamiques très différents, les systèmes sont tous deux caractérisés par une activité intrusive intense le long de rift zones et ont subi des déstabilisations latérales récurrentes durant leur évolution. Parmi les facteurs d'instabilité, les exemples de La Réunion et de Stromboli soulignent l'influence majeure des complexes intrusifs dans la croissance et le démantèlement des volcans, comme le prouvent les études de terrain et la surveillance des ces volcans actifs. Les modèles classiques considèrent que le processus d'instabilité latérale en domaine volcanique résulte de la mise en place d'une ou plusieurs intrusions verticales, entrainant des mouvements de flancs le long d'une surface de glissement pré-existante. De nouvelles données de terrain obtenues au Piton des Neiges (La Réunion), ainsi que des données de littérature sur d'autres édifices, ont permis de mettre en évidence le rôle des intrusions sub-horizontales dans les déstabilisations de flancs et de caractériser la géométrie des intrusions sub-verticales et sub-horizontales au sein des volcans basaltiques. Cette étude compare les résultats de la modélisation numérique des champs de déplacements de surface crées par la mise en place d'intrusions magmatiques à faible / fort pendage dans les édifices basaltiques, grâce à une méthode d'éléments frontières mixte (Mixed Boundary Element Method), dans le but de déterminer le comportement mécanique d'un édifice soumis à des injections magmatiques sous différents champs de contraintes. Les résultats de cette étude montrent qu'un champ de contraintes anisotrope favorise le glissement le long des intrusions, généré par la contrainte cisaillante co-intrusive, à l'origine de déplacements à l'échelle du flanc de l'édifice. Ces déplacements de grande ampleur, préférentiellement liés à des intrusions subhorizontales, peuvent probablement déclencher des grands glissements latéraux si leur amplitude dépasse le seuil de stabilité de l'édifice. L'application des résultats théoriques à des exemples réels de déformations enregistrées sur des volcans basaltiques (dont La Réunion et Stromboli, au cours de leurs crises éruptives de 2007) révèle que le modèle de déstabilisation associée à des intrusions sub-verticales est un mécanisme pouvant générer des effondrements de flancs sur des petits édifices à fortes pentes comme Stromboli. De plus, nos données de terrain et les résultats de modélisation confirment l'importance des intrusions sub-horizontales dans l'évolution morpho-structurale des grands édifices basaltiques à faibles pentes comme le Piton de la Fournaise (La Réunion), l'Etna ou le Kilauea, et plus particulièrement dans les instabilités de flancs pouvant causer des tsunamis dévastateurs. / Most basaltic volcanoes are affected by recurrent lateral instabilities during their evolution. Numerous factors have been shown to be involved in the process of flank destabilization occurring over long periods of time or by instantaneous failures. However, the role of these factors on the mechanical behaviour and stability of volcanic edifices is poorly-constrained as lateral failure usually results from the combined effects of several parameters. Our study focuses on the morphological and structural comparison of two end-member basaltic systems, La Reunion (Indian ocean, France) and Stromboli (southern Tyrrhenian sea, Italy). We showed that despite major differences on their volumes and geodynamic settings, both systems present some similarities as they are characterized by an intense intrusive activity along well-developed rift zones and recurrent phenomena of flank collapse during their evolution. Among the factors of instability, the examples of la Reunion and Stromboli evidence the major contribution of intrusive complexes to volcano growth and destruction as attested by field observations and the monitoring of these active volcanoes. Classical models consider the relationship between vertical intrusions of magma and flank movements along a preexisting sliding surface. A set of published and new field data from Piton des Neiges volcano (La Reunion) allowed us to recognize the role of subhorizontal intrusions in the process of flank instability and to characterize the geometry of both subvertical and subhorizontal intrusions within basaltic edifices. This study compares the results of numerical modelling of the displacements associated with high-angle and low-angle intrusions within basaltic volcanoes. We use a Mixed Boundary Element Method to investigate the mechanical response of an edifice to the injection of magmatic intrusions in different stress fields. Our results indicate that the anisotropy of the stress field favours the slip along the intrusions due to cointrusive shear stress, generating flank-scale displacements of the edifice, especially in the case of subhorizontal intrusions, capable of triggering large-scale flank collapses on basaltic volcanoes. Applications of our theoretical results to real cases of flank displacements on basaltic volcanoes (such as the 2007 eruptive crisis at La Reunion and Stromboli) revealed that the previous model of subvertical intrusions-related collapse is a likely mechanism affecting small-scale steeply-sloping basaltic volcanoes like Stromboli. Furthermore, our field study combined to modelling results confirms the importance of shallow-dipping intrusions in the morpho-structural evolution of large gently-sloping basaltic volcanoes like Piton de la Fournaise, Etna and Kilauea, with particular regards to flank instability, which can cause catastrophic tsunamis.

No description available.

With an increase in the number of people living in proximity to active volcanic centres worldwide, there is a greater need to provide effective and engaging education and outreach programmes to reduce vulnerability and prepare exposed communities for potential future volcanic eruptions. The finalisation of the Sendai Framework (UNISDR, 2015a) has also cemented the need for disaster risk managers to engage at-risk communities with education and outreach programmes, to reduce the number of deaths and injuries caused by volcanic eruptions worldwide. Education and outreach programmes are already commonplace for disaster risk reduction, with many taking the form of traditional presentations, maps, diagrams, TV and radio broadcasts. In recent years, there has been a shift towards the use of more creative media to communicate volcanic hazards and engage populations in outreach activities. These have included films, comic strips, puppet shows, board games and video games. However, to-date there is little empirical evidence for the use of these media with at-risk communities. This research seeks to address this issue by providing evidence for the effective use of creative media for volcanic hazard education by adopting the use of video games (or serious games). To assess how effective serious games could be as an education tool, a bespoke video game (St. Vincent’s Volcano) was developed collaborative with disaster risk agencies and communities on the Eastern Caribbean island of St. Vincent and then trialled with adults and students from across the island. A range of outreach sessions were adopted to compare and contrast the applications of the game and to identify the most effective method of its delivery. These sessions included a traditional outreach presentation used as a control, and a group of UK students for a cohort comparison. Data were collected through a mixed-methods approach. Overall the results of the study demonstrate how successful the game can be as an education tool, promoting knowledge improvement in players. The results also demonstrate how the role of the outreach instructor is important to encourage engagement and can result in higher levels of overall positive engagement exhibited by the students. The game was also successful at promoting knowledge gain and engagement with adult participants. The results also demonstrated promise for games in promoting longer-term knowledge retention and for improving awareness of existing outreach materials. This research provides a foundation for the increased integration of emerging technologies within traditional education sessions. The work also shares some of the challenges and lessons learnt throughout the development and testing processes and provides recommendations for researchers looking to pursue a similar study or to adopt the use of serious games.

The interaction of magma with continental crust at convergent margins is fundamental to understanding if and how continents grow. Isotopic and elemental data constrain the progressive stages of development of the magmatic underpinnings of the long-lived Aucanquilcha Volcanic Cluster (AVC), situated atop the thick continental crust of the central Andes in northern Chile. Whole rock data are used in conjunction with mineral compositions to infer processes that gave rise to eleven million years of intermediate, dominantly dacite, arc volcanism. A pulse of volcanic activity at the AVC between ~5 and 2 Ma is bracketed by more sluggish rates. We document chemical changes in the lavas that accompany this eruptive evolution. Trace element data suggest that crystal fractionation and magma mixing were the dominant mechanisms generating the diversity observed in the AVC whole rock data. Fractionation was dominant during early and waning stages of magmatism, and magma mixing was an important process during the high flux period. Peak thermal maturity of the AVC underpinnings coincided with the high magma flux and likely promoted open system processes during this time. Mineral compositions from zircon, amphibole, pyroxene, and Fe-Ti oxides confirm the importance of material recycling in the production of evolved AVC rocks. Various geothermometers were employed to calculate the pre-eruptive conditions of AVC magma using mineral compositions. Pressure estimates from amphibole and two-pyroxene barometry indicate crystallization depths of 1 ��� 5 kb and 4 ��� 6 kb, respectively. Temperature estimates from zircon, Fe-Ti oxides, amphiboles, and pyroxenes indicate temperatures ranging from ~700��C to 1100��C. Zircon temperatures are always the lowest (700��C - 950��C), and pyroxene temperatures are always the highest (1000��C - 1100��C), with Fe-Ti oxide and amphiboles temperatures falling in between. U-Pb ages from zircons and thermometry from individual samples evidence the thermal maturation and consolidation of the underpinnings below the AVC, presumably culminating in a large, crystal-rich mush zone where magmas were trapped and processed. It is in these middle to upper crustal zones where magmatic diversity is attenuated and giant, relatively homogeneous batholiths are formed. Isotopes of AVC lavas are similar to values observed from other central Andes volcanic centers. Lead isotopes are consistent with the AVC's location within a Pb isotope transition zone between the Antofalla and Arequipa basement terranes. Oxygen and Sr isotopic ratios are high and Nd isotopic ratios low with respect to a depleted mantle. Through time, ������Sr/������Sr values of AVC lavas progressively increase from lows of ~0.70507 to ~0.70579 (upper values of 0.70526 to 0.70680), and ��Nd values decrease from highs of -1.0 to -4.6 (lows of -1.6 to -7.3). Similarly, O isotopes (�������O) show a slight increase in base level through time from lows of 6.5��� to 7.0��� (highs of 6.75��� ��� 7.5���). Dy/Yb and Sm/Yb ratios also increased systematically from highs of 2.11 to 3.45, and 2.76 to 6.67, respectively. Despite the temporal isotopic variation, there is little isotopic variation with indices of fractionation, suggesting this signal is the consequence of deep magmatic processing, here attributed to an expanding zone of melting, assimilation, storage, and homogenization (MASH) of mantle-derived magma in the deep crust. Upward expansion brought the MASH zone into contact with rocks that were increasingly evolved with respect to Sr and Nd isotopes, explaining the isotopic shifts. Downward expansion of the MASH zone enhanced garnet stability during basalt fractionation, explaining the increased Dy/Yb and Sm/Yb ratios. Mass balance calculations involving Sr, Nd, and O isotope modeling are consistent with a crustal component making up 10 - 30% of AVC lavas, implying that although the history of central Andean magmatism is replete with large scale crustal recycling, the current phase is largely a crust formation event. / Graduation date: 2012

No description available.

Οι σεισμοί και οι ηφαιστειακές εκρήξεις αποτελούν την επιφανειακή έκφραση μιας δυναμικής του βάθους. Αυτό από μόνο του παραπέμπει σε κάτι μη απτό και μη άμεσα παρατηρήσιμο. Όμως τα δύο αυτά φαινόμενα καταφέρνουν να κεντρίσουν το ενδιαφέρον μικρών και μεγάλων κάνοντάς τους να σχηματίζουν τις δικές τους παραστάσεις για τις δύο έννοιες. Στην παρούσα έρευνα, μελετήσαμε τις ιδέες που κατέχουν τα παιδιά της προσχολικής ηλικίας για τους σεισμούς, τα ηφαίστεια και τη δημιουργία αυτών, πριν αλλά και μετά από μια οργανωμένη διδακτική παρέμβαση. Επίσης, έγινε προσπάθεια καταγραφής των συναισθημάτων που εκφράζονται από τα παιδιά για το φαινόμενο του σεισμού αλλά και των μέτρων προστασίας που τείνουν να υιοθετούν σε μια τέτοια περίσταση. Το δείγμα αποτέλεσαν 63 παιδιά προσχολικής ηλικίας από ένα δημόσιο Νηπιαγωγείο στην ευρύτερη περιοχή της Πάτρας. Τα παιδιά φάνηκε πως είχαν σχηματίσει ήδη πριν τη διδακτική παρέμβαση κάποιες πρώτες παραστάσεις για τα φαινόμενα αυτά. Μετά την ολοκλήρωση της διδακτικής παρέμβασης παρατηρήθηκε ότι οι παραστάσεις αυτές βελτιώθηκαν αρκετά με κάποιες από αυτές να πλησιάζουν αρκετά το επιστημονικό μοντέλο. Τέλος, τα συναισθήματα που εκφράστηκαν από τα παιδιά καθ’ όλη τη διάρκεια της μελέτης αυτής σχετίζονταν με την κατανόηση της σημαντικότητας του εν λόγω θέματος: παρατηρήθηκε μια μετάβαση από το συναίσθημα φόβου ή πανικού σε συναισθήματα που είχαν να κάνουν περισσότερο με ηρεμία και διατήρηση της ψυχραιμίας προκειμένου να προστατευθούν σε περίπτωση σεισμού. / Earthquakes and volcanic eruptions are the surface expression of a dynamic depth. This by itself refers to something intangible and not directly observable; but these two phenomena manage to pique the interest of both preschoolers and adults and make them form their own representations for both concepts. In this research, we studied the ideas held by the preschoolers on earthquakes, volcanoes and the creation of these two, before and after an organized teaching intervention. Also, an attempt was made to record the emotions expressed by children about the earthquakes and the protective measures they tend to adopt in such situations. The sample consisted of 63 preschool children from a public kindergarten located in the city of Patras. Ever before the teaching intervention, children had already formed some early representations for these phenomena, representations that were enriched (approaching even the scientific model) after the didactic intervention had been completed. Finally, the feelings expressed by the children throughout the study resulted from the understanding of the significance of this issue: there was a transition from the feeling of fear or panic to feelings that had more to do with staying calm and keeping their composure (in order to protect themselves) in a case of an earthquake.

No description available.

Most basaltic volcanoes are affected by recurrent lateral instabilities during their evolution. Numerous factors have been shown to be involved in the process of flank destabilization occurring over long periods of time or by instantaneous failures. However, the role of these factors on the mechanical behaviour and stability of volcanic edifices is poorly-constrained as lateral failure usually results from the combined effects of several parameters. Our study focuses on the morphological and structural comparison of two end-member basaltic systems, La Reunion (Indian ocean, France) and Stromboli (southern Tyrrhenian sea, Italy). We showed that despite major differences on their volumes and geodynamic settings, both systems present some similarities as they are characterized by an intense intrusive activity along well-developed rift zones and recurrent phenomena of flank collapse during their evolution. Among the factors of instability, the examples of la Reunion and Stromboli evidence the major contribution of intrusive complexes to volcano growth and destruction as attested by field observations and the monitoring of these active volcanoes. Classical models consider the relationship between vertical intrusions of magma and flank movements along a preexisting sliding surface. A set of published and new field data from Piton des Neiges volcano (La Reunion) allowed us to recognize the role of subhorizontal intrusions in the process of flank instability and to characterize the geometry of both subvertical and subhorizontal intrusions within basaltic edifices. This study compares the results of numerical modelling of the displacements associated with high-angle and low-angle intrusions within basaltic volcanoes. We use a Mixed Boundary Element Method to investigate the mechanical response of an edifice to the injection of magmatic intrusions in different stress fields. Our results indicate that the anisotropy of the stress field favours the slip along the intrusions due to cointrusive shear stress, generating flank-scale displacements of the edifice, especially in the case of subhorizontal intrusions, capable of triggering large-scale flank collapses on basaltic volcanoes. Applications of our theoretical results to real cases of flank displacements on basaltic volcanoes (such as the 2007 eruptive crisis at La Reunion and Stromboli) revealed that the previous model of subvertical intrusions-related collapse is a likely mechanism affecting small-scale steeply-sloping basaltic volcanoes like Stromboli. Furthermore, our field study combined to modelling results confirms the importance of shallow-dipping intrusions in the morpho-structural evolution of large gently-sloping basaltic volcanoes like Piton de la Fournaise, Etna and Kilauea, with particular regards to flank instability, which can cause catastrophic tsunamis.