Strain field analysis on Montserrat (W.I.) as tool for assessing permeable flow paths in the magmatic system of Soufrière Hills Volcano

Strain dilatometers have been operated on the volcanic island of Montserrat (West Indies) for more than a decade and have proven to be a powerful technique to approach short-term dynamics in the deformational field in response to pressure changes in the magmatic system of the andesitic dome-building Soufrière Hills Volcano (SHV). We here demonstrate that magmatic activity in each of the different segments of the SHV magmatic system (shallow dyke-conduit, upper and lower magma chambers) generates a characteristic strain pattern that allows the identification of operating sources in the plumbing system based on a simple scheme of amplitude ratios. We use this method to evaluate strain data from selected Vulcanian explosions and gas emission events that occurred at SHV between 2003 and 2012. Our results show that the events were initiated by a short phase of contraction of either one or both magma chambers and a simultaneous inflation of the shallow feeder system. The initial phase of the events usually lasted only tens to hundreds of seconds before the explosion/gas emission started and the system recovered. The short duration of this process points at rapid transport of fluids rather than magma ascent to generate the pressure changes. We suggest the propagation of tensile hydraulic fractures as viable mechanism to provide a pathway for fluid migration in the magmatic system at the observed time scale. Fluid mobilization was initiated by a sudden destabilization of large pockets of already segregated fluid in the magma chambers. Our study demonstrates that geodetic observables can provide unprecedented insights into complex dynamic processes within a magmatic system commonly assessed by theoretical modeling and petrologic observations. Key Points Strain data analysis from explosions/degassing events at Soufriere Hills Volcano Pressure release deep within the magmatic system sec-min prior to events Rapid gas rise from magma reservoir to surface via tensile hydraulic fractures © 2014. American Geophysical Union. All Rights Reserved

Futurevolc: a European volcanological supersite observatory in Iceland, a monitoring system and network for the future

FUTUREVOLC is a collaborative project funded through the FP7 Environment Supersite Concept call encompassing 26 partners in 10 countries. The main objectives of FUTUREVOLC are to establish an integrated volcanological monitoring procedure through European collaboration, develop new methods to evaluate volcanic crises, increase scientific understanding of magmatic processes and improve delivery of relevant information to civil protection and authorities. FUTUREVOLC is in the first of its 3.5 year duration, therefore this paper presents aims and expectations rather than results

SolEx: A Model for Mixed COHSCl-volatile Solubilities and Exsolved Gas Compositions in Basalt

We present a software application, SolEx, to calculate basaltic melt and coexisting vapour compositions in the system C–O–H–S–Cl. Such a model has great utility in interpreting emitted gas and melt inclusion compositions, especially through the incorporation of sulphur and chlorine, the most commonly measured volcanic gas species. We assume that the behaviour of the fluid phase is controlled by the volumetrically dominant volatile species, H2O and CO2, whereas sulphur and chlorine partition between the melt and fluid phases. Melt–fluid partition coefficients for S and Cl were parameterised from measurements by Lesne et al. (2011a, p. 1737). The model of Churakov and Gottschalk (2003a, p. 2415) was applied to calculate fugacity coefficients and the equilibrium constants for the reaction imelt → ifluid were thereby deduced. SO2 dominates at oxidation states of ΔNNO \u3e 0.5 (Jugo et al., 2010, p. 5926), where this model is applicable. In the forward model, total volatile inventories and melt composition are specified by the user. The parameterisation of Dixon (1997, p. 368) is used to predict the partitioning of CO2 and H2O between vapour and melt phases. An iterative procedure is employed to predict the partitioning of S and Cl components between fluid and melt phases. Melt and gas compositions and gas volume fraction are thereby modelled over pressures in the range 5–4000 bar. This approach satisfactorily reproduces independent literature data on S and Cl behaviour in basalt. SolEx is a user-friendly software package available for OS X and Windows, facilitating modelling of closed- and open-system C–O–H–S–Cl degassing in basalts

Isothermal combustor prediffuser and fuel injector feed arm design optimization using the Prometheus design system

The Prometheus combustor design system aims to reduce the complexity of evaluating combustor designs by automatically defining pre-processing, simulation and post-processing tasks based on the automatic identification of combustor features within the CAD environment. This system enables best practice to be codified and topological changes to a combustor's design to be more easily considered within an automated design process. The following paper presents the Prometheus combustor design system and its application to the multi-objective isothermal optimization of a combustor prediffuser and the multi-fidelity isothermal optimization of a fuel injector feed arm in combination with a surrogate modelling strategy accelerated via a high performance graphical processing uni

Developing and evaluating a Frailty Index for older South Africans – findings from the HAALSI study

Background: despite rapid population ageing, few studies have investigated frailty in older people in sub-Saharan Africa. We tested a cumulative deficit frailty index in a population of older people from rural South Africa. Methods: analysis of cross-sectional data from the Health and Ageing in Africa: Longitudinal Studies of an INDEPTH Community (HAALSI) study. We used self-reported diagnoses, symptoms, activities of daily living, objective physiological indices and blood tests to calculate a 32-variable cumulative deficit frailty index. We fitted Cox proportional hazards models to test associations between frailty category and all-cause mortality. We tested the discriminant ability of the frailty index to predict one-year mortality alone and in addition to age and sex. Results: in total 3,989 participants were included in the analysis, mean age 61 years (standard deviation 13); 2,175 (54.5%) were women. The median frailty index was 0.13 (interquartile range 0.09–0.19); Using population-specific cutoffs, 557 (14.0%) had moderate frailty and 263 (6.6%) had severe frailty. All-cause mortality risk was related to frailty severity independent of age and sex (hazard ratio per 0.01 increase in frailty index: 1.06 [95% confidence interval 1.04–1.07]). The frailty index alone showed moderate discrimination for one-year mortality: c-statistic 0.68–0.76; combining the frailty index with age and sex improved performance (c-statistic 0.77–0.81). Conclusion: frailty measured by cumulative deficits is common and predicts mortality in a rural population of older South Africans. The number of measures needed may limit utility in resource-poor settings.Dr Barker and Professor Witham acknowledge support from the NIHR Newcastle Biomedical Research Centre. ANW is supported by the Fogarty International Centre of the National Institutes of Health under Award Number K43TW010698. National Institutes of Ageing (NIH) grant 1P01AG041710-01A1 National Dept of Science and Innovation (via South African Medical Research Council); Wellcome Trust (058893/Z/99/A; 069683/Z/02/Z; 085477/Z/08/Z; 085477/B/08/Z)