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The overall aim of this research project has been to develop a reference dataset of 19 Holocene silicic Icelandic tephra layers sourced from the Torfajökull, Askja, Katla, Öræfajökull and Hekla volcanic systems. The dataset comprises geochemical data (including major, trace and rare earth element data for bulk and glass phases collected by XRF, electron microprobe, ion probe and laser ablation ICP-MS) and physical data (including sedimentary logs, field photographs, distribution maps and GPS localities of reference sections). Results indicate that Icelandic volcanic systems show unique geochemical signatures which result from the systems proximity to the active rifting zone and the proposed upwelling mantle plume that underlies the island. Within individual volcanic systems, eruptions produce tephra with distinct geochemical characteristics, which allow for the independent confirmation of tephra identity. The identification and discrimination of tephra layers can in some cases be achieved using major element chemistry (e.g. Hekla, H1104 – H5) while other tephra layers can only be discriminated using trace element chemistry (e.g. Torfajökull, Landnám and Gràkolla). Certain tephra layers however show near-identical geochemistry and therefore discrimination is not possible (e.g. Hekla, HA, HB, HC, HM, HN, HX, HY, HZ) without the incorporation of other proxy data. Icelandic micro-tephra horizons are identified in soil, lacustrine and marine sedimentary sequences and are used for dating and correlation in Quaternary studies. Data collected for this project will facilitate reliable data comparison and tephra identification between proximal and distal localities across the North Atlantic region. The data may also contribute to the debate regarding the formation of silicic rocks within Iceland, particularly with regard to the Hekla central volcano. The geochemical data collected for this thesis shows distinct age-dependant geochemical sub-groups suggesting temporal sub-surface relocation of the Hekla magma source.

Thesis (M.S.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Background: In 2001 an assessment tool for predicting fracture risk in postmenopausal women was developed. An index based on a small number of risk factors that are easily assessed was developed called the Fracture Index. The value of this index ranges from 0-13 with higher number associated with higher five year probability of fracture. The magnitude of the morbidity and mortality associated with osteoporosis makes it valuable for health care professionals to know if a treatment to prevent fractures is cost effective or not. Objective: To investigate at what Fracture Index value it becomes cost effective to treat postmenopausal women with alendronate to prevent hip fractures. The focus is on Icelandic women. Design: A Markov model was developed to model the disease progression for women 65 years of age to 85 years of age which is the average life expectancy for women in Iceland. Cost effectiveness of alendronate vs. no treatment was assessed by transitioning women in the model every six months between different health states. In the base-case five year treatment with alendronate was assumed. Results: At Fracture Index 1-2 the incremental cost effectiveness ratio (ICER) was 27,467,073 ISK (238,844$) which is not considered to be cost effective. At Fracture Index 3-4 the ICER was 4,349,2511SK (37,820$) which has a 59% probability of being cost effective if the per capita GOP (4,800,000 ISK) for Iceland is used as a threshold for cost effectiveness. However cost effectiveness for Fracture Index 3-4 depends largely on the assumptions made in the model, some of which are uncertain such as drug cost, drug efficacy and appropriate discount rate. Treatment with Alendronate is cost effective for Fracture Index 5 and variation in the model's assumptions does not change that result. Conclusions: The results of this study indicate that treating osteoporotic women with alendronate to prevent hip fractures becomes cost effective at Fracture Index 5 with a 1.9% five year probability of hip fracture. / 2031-01-01

Understanding dykes is vital as they serve both as bodies that build the crust and as conduits that feed eruptions. The 2014-15 Bárðarbunga-Holuhraun rifting event comprised the best-monitored dyke intrusion to date and the largest eruption in Iceland in 230 years. Over a 13 day period magma propagated laterally from the subglacial Bárðarbunga volcano, Iceland, along a 48 km path before erupting in the Holuhraun lava field on 29 August 2014. A huge variety of seismicity was produced, including over 30,000 volcano-tectonic earthquakes (VTs) associated with the dyke propagation at ∼ 6 km depth below sea level, and long-period seismicity - both long-period earthquakes (LPs) and tremor - associated with the eruption processes. The Cambridge University seismic network in central Iceland recorded the dyke seismicity in unprecedented detail, allowing high resolution analyses to be carried out. This dissertation comprises two parts: study of 1) the volcano-tectonic dyke-induced seismicity and 2) the long-period seismicity associated with eruption processes. Volcano-tectonic earthquakes induced by the lateral dyke intrusion were relocated, using cross-correlated, sub-sample relative travel times. The ∼ 100 m spatial resolution achieved reveals the complexity of the dyke propagation pathway and dynamics (jerky, segmented), and allows us to address the precise relationship between the dyke and seismicity. The spatio-temporal characteristics of the induced seismicity can be directly linked in the first instance to propagation of the tip and opening of the dyke, and following this - after dyke opening - indicate a relationship with magma pressure changes (i.e. dyke inflation/deflation), followed by a general 'post-opening' decay. Seismicity occurs only at the base of the dyke, where dyke-imposed stresses - combined with the background tectonic stress (from regional extension over > 200 years since last rifting) - are sufficient to induce failure of pre-existing weaknesses in the crust, while the greatest opening is at shallower depths. Emplacement oblique to the spreading ridge resulted in left-lateral shear motion along the distal dyke section (studied here), and a prevalence of left-lateral shear failure. Fault plane strikes are predominately independent of the orientation of lineations delineated by the hypocenters, indicating that they are controlled by the underlying host rock fabric. Long-period earthquakes and tremor were systematically detected and located during the dyke propagation phase and the first week of the eruption. Clusters of highly similar, repetitive LPs were identified, with a peak frequency of ∼ 1 Hz and clear P and S phases followed by a long-duration coda. The source mechanisms were remarkably consistent between clusters and also fundamentally different to those of the VTs. The clusters were accurately located near each of three ice cauldrons (depressions formed by basal melting) that were observed on the surface of Dyngjujökull glacier above the path of the dyke. Most events were in the vicinity of the northernmost cauldron, at shallower depth than the VTs associated with lateral dyke propagation. At the two northerly cauldrons, periods of shallow seismic tremor following the clusters of LPs were also observed. Given that the LPs occurred at ∼ 4 km depth and in swarms during times of dyke-stalling, it is inferred that they result from excitation of magmatic fluid-filled cavities and indicate magma ascent. The tremor may then represent the climax of the vertical melt movement, arising from either rapid, repeated excitation of the same LP cavities, or sub-glacial eruption processes. This long-period seismicity therefore highlights magma pathways between the depth of the dyke-VT earthquakes and the surface. Notably, no tremor is detected associated with each cauldron, despite melt reaching the base of the overlying ice cap, a concern for hazard forecasting.

Magmatism on Iceland is dominated by the eruption of tholeiitic lavas along two NE-SW trending rift zones that represent the loci of new crustal formation. Small volumes of transitional to alkaline magmas erupted along the ~120 km long Snæfellsnes Peninsula in western Iceland. The Snæfellsnes Peninsula is broken into three distinct volcanic systems; Ljósufjöll, Lýsuskard, and Snæfellsjökull. This study examines the geochemical compositions and depths of crystallization of alkaline basaltic glass to see if these features vary spatially along the peninsula. Glass MgO values range from 3.4 to 9.0 wt %, TiO2 ranges from 0.9 – 4.8 wt. % increasing westward along the peninsula. Estimations of crystallization pressures, based on the pressure dependence of ol±plag±cpx, average 4.6 ± 2.8 kbar, translating to depth a depth of 16.1 ± 10 km generally increasing with distance from the main rift zones. In some cases, cox-melt barometry was also used as a check on the glass cotectic pressures. Crustal thickness beneath Snæfellsnes has been estimated to be ~25 km, suggesting mid to lower crustal magma storage depths. Calculated depths in Snæfellsjökull and Lýsuskard are consistent and deep (22 ± 2.4 km) whereas the Ljósufjöll system is more varied. The Ljósufjöll system displays two groupings of depths, split lengthwise. The northern group exhibits depth between 15-26 km, like the rest of the peninsula, while the southern group has no discernable pattern. Previous data on post-glacial lavas reveals broad spatial trends in REEs across the peninsula. Basaltic glasses exhibit a wide range of La/Sm (1 – 5.6) suggesting a variation in melting percentage over a small area. Samples west of 22.33⁰W have higher Dy/Yb (>2.1) indicating a deeper melting depth due to residual garnet as well as a higher La/Sm (>10) indicative of a smaller degree of melting and/or an enriched source. These data have shown that melt storage occurs at near Moho depths along the peninsula but is highly variable in the eastern Ljósufjöll.

Thesis (Ph.D.) - University of St Andrews, November 2008.

This diploma thesis concerns with icelandic financial and mostly banking crisis. The first part is dedicated to presentation of Iceland as a state in general. The second part draws an economic development from 2000 to 2008 and consequently describes general causes of the crisis and recognizes them on the annual reports of the Kaupthing Bank. Third part shows the course of the crisis and impact on the regional financial system and institutions. In a closing, the part four deals with development after the crisis.

Research and thoughts on how tourism in Iceland can interact with and influence the icelandic nature in a positive way. The project focuses on the reforestation of Iceland and how buildings and architecture can invite tourists to have a positive effect on the island. The project combines the activity of hiking and the function of the tree nursery to result in a new kind of eco tourist. Where Tourists can become a helpful force to the Icelandic nature, planting one tree at a time.

The primary purpose of this study was to examine the nature of social skills in socially anxious children from a social learning theory perspective. The reasons why socially anxious children often perform poorly in social situations have not yet been fully resolved. Is it due to lack of social skills or are these children too inhibited and nervous in social situations to exhibit the skills they possess? Ninety-two elementary and middle school children (age 10-14 years) in Kopavogur, Iceland participated in the study and completed questionnaires on social phobia and anxiety, social skills, assertiveness, and self-efficacy and outcome expectancy in social situations with friends and strangers. Based on how socially anxious they reported to be on the Social Phobia and Anxiety Inventory for Children (SPAI-C), 59 children were selected for further study. Results showed that socially anxious children reported being less socially skilled, less assertive with strangers than with friends, and lower in self-efficacy and outcome expectancy than children in a normal comparison group. However, the socially anxious children were not rated as less skilled by parents or teachers than the other children. Implications for the assessment and treatment of children and adolescents with social anxiety are discussed. / Master of Science

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