Short-term volcanic hazard assessment through Bayesian inference: Retrospective application to the Pinatubo 1991 volcanic crisis

© 2014 . One of the most challenging aspects of managing a volcanic crisis is the interpretation of the monitoring data, so as to anticipate to the evolution of the unrest and implement timely mitigation actions. An unrest episode may include different stages or time intervals of increasing activity that may or may not precede a volcanic eruption, depending on the causes of the unrest (magmatic, geothermal or tectonic). Therefore, one of the main goals in monitoring volcanic unrest is to forecast whether or not such increase of activity will end up with an eruption, and if this is the case, how, when, and where this eruption will take place. As an alternative method to expert elicitation for assessing and merging monitoring data and relevant past information, we present a probabilistic method to transform precursory activity into the probability of experiencing a significant variation by the next time interval (i.e. the next step in the unrest), given its preceding evolution, and by further estimating the probability of the occurrence of a particular eruptive scenario combining monitoring and past data. With the 1991 Pinatubo volcanic crisis as a reference, we have developed such a method to assess short-term volcanic hazard using Bayesian inference.This research has been partially funded by the European Commission (FP7 Theme: ENV.2011.1.3.3-1; Grant 282759: VUELCO) and by the Aon Benfield UCL Hazard Centre. All data and information used to reproduce the results in the case study have been extracted from the public source Punongbayan and Newhall (1996) edited monograph on the Mt Pinatubo eruption.Peer Reviewe

Probabilistic approach to decision-making under uncertainty during volcanic crises: retrospective application to the El Hierro (Spain) 2011 volcanic crisis

© 2014, The Author(s). Understanding the potential evolution of a volcanic crisis is crucial for designing effective mitigation strategies. This is especially the case for volcanoes close to densely populated regions, where inappropriate decisions may trigger widespread loss of life, economic disruption, and public distress. An outstanding goal for improving the management of volcanic crises, therefore, is to develop objective, real-time methodologies for evaluating how an emergency will develop and how scientists communicate with decision-makers. Here, we present a new model Bayesian Decision Model (BADEMO) that applies a general and flexible, probabilistic approach to managing volcanic crises. The model combines the hazard and risk factors that decision-makers need for a holistic analysis of a volcanic crisis. These factors include eruption scenarios and their probabilities of occurrence, the vulnerability of populations and their activities, and the costs of false alarms and failed forecasts. The model can be implemented before an emergency, to identify actions for reducing the vulnerability of a district; during an emergency, to identify the optimum mitigating actions and how these may change as new information is obtained; and after an emergency, to assess the effectiveness of a mitigating response and, from the results, to improve strategies before another crisis occurs. As illustrated by a retrospective analysis of the 2011 eruption of El Hierro, in the Canary Islands, BADEMO provides the basis for quantifying the uncertainty associated with each recommended action as an emergency evolves and serves as a mechanism for improving communications between scientists and decision-makers.This research has been funded by the European Commission (FP7 Theme: ENV.2011.1.3.3-1; Grant 282759: VUELCO).Peer Reviewe

Long-term volcanic hazard assessment on El Hierro (Canary Islands)

Long-term hazard assessment, one of the bastions of risk-mitigation programs, is required for land-use planning and for developing emergency plans. To ensure quality and representative results, long-term volcanic hazard assessment requires several sequential steps to be completed, which include the compilation of geological and volcanological information, the characterisation of past eruptions, spatial and temporal probabilistic studies, and the simulation of different eruptive scenarios. Despite being a densely populated active volcanic region that receives millions of visitors per year, no systematic hazard assessment has ever been conducted on the Canary Islands. In this paper we focus our attention on El Hierro, the youngest of the Canary Islands and the most recently affected by an eruption. We analyse the past eruptive activity to determine the spatial and temporal probability, and likely style of a future eruption on the island, i.e. the where, when and how. By studying the past eruptive behaviour of the island and assuming that future eruptive patterns will be similar, we aim to identify the most likely volcanic scenarios and corresponding hazards, which include lava flows, pyroclastic fallout and pyroclastic density currents (PDCs). Finally, we estimate their probability of occurrence. The end result, through the combination of the most probable scenarios (lava flows, pyroclastic density currents and ashfall), is the first qualitative integrated volcanic hazard map of the island.This research was partially funded by IGME, CSIC and the European Commission (FT7 Theme: ENV.2011.1.3.3-1; Grant 282759: “VUELCO”), and MINECO grant CGL2011-16144-E.Peer reviewe

¿Qué ocurre a los 24 meses del inicio del tratamiento en una muestra de personas con dependencia de la cocaína?

La evolución de las personas que están en tratamiento por consumo de cocaína en Centros de Drogodependencias públicos, es un tema relevante debido al notable incremento de la demanda de estos tratamientos en los últimos años. El objetivo del presente estudio es analizar la evolución de personas con dependencia de la cocaína que han recibido tratamiento en Centros públicos de Drogodependencias de Galicia, tras dos años de haberse realizado una evaluación inicial. La muestra el presente estudio es de 38 sujetos que formaban parte de una muestra inicial más amplia (N = 115), y las variables que se analizan son: el consumo de sustancias, el ajuste social con la escala del O.T.I., problemas con la justicia y el malestar psicológico percibido por el sujeto evaluado con las subescalas e índices del SCL-90 R. Los resultados obtenidos son: a los dos años, el 78.9% de la muestra localizada no ha consumido cocaína en el mes previo a la evaluación, lo cual representa un 26% de la muestra inicial, y una disminución del malestar percibido por el sujeto. Estos resultados indican una evolución positiva de la muestra de personas en tratamiento por dependencia de la cocaína a los dos años que ha sido analizada en el presente estudioThe evolution of people in treatment for cocaine dependence at public Drug Abuse Centers is a relevant topic in view of the notable increase in demand for such treatment in recent years. The aim of the present study was to analyze the evolution of people with cocaine dependence receiving treatment at public Drug Abuse Centers in Galicia (NW Spain), two years after the initial assessment for inclusion on the treatment program. The sample for the present study was 38 participants who formed part of a larger initial sample (N = 115). The variables analyzed were: substance use, social adjustment on the O.T.I. scale, problems with the legal system and perceived psychological distress as assessed with the scales and indices of the SCL-90 R. The results indicate that, after two years of treatment, 78.9% of those in the sample located (26% of the initial sample) had not consumed cocaine in the month prior to assessment, and that there was a reduction in psychological distress. These results indicate a positive evolution after two years of the sample of people in treatment for cocaine dependence assessed in this studyS

Physical Mechanisms for Vertical-CLVD Earthquakes at Active Volcanoes

Many volcanic earthquakes large enough to be detected globally have anomalous focal mechanisms and frequency content. In a previous study, we examined the relationship between active volcanism and the occurrence of a specific type of shallow, non-double-couple earthquake. We identified 101 earthquakes with vertical compensated-linear-vector-dipole (vertical-CLVD) focal mechanisms that took place near active volcanoes between 1976 and 2009. The majority of these earthquakes, which have magnitudes 4.3 less than or equal to MW less than or equal to 5.8, are associated with documented episodes of volcanic unrest. Here we further characterize vertical-CLVD earthquakes and explore possible physical mechanisms. Through teleseismic body-wave analysis and examination of the frequency content of vertical-CLVD earthquakes, we demonstrate that these events have longer source durations than tectonic earthquakes of similar magnitude. We examine the covariance matrix for one of the best-recorded earthquakes and confirm that the isotropic and pure vertical-CLVD components of the moment tensor cannot be independently resolved using our long-period seismic data set. Allowing for this trade-off, we evaluate several physical mechanisms that may produce earthquakes with deviatoric vertical-CLVD moment tensors. We find that physical mechanisms related to fluid flow and volumetric changes are incompatible with seismological, geological, and geodetic observations of vertical-CLVD earthquakes. However, ring-faulting mechanisms explain many characteristics of vertical-CLVD earthquakes, including their seismic radiation patterns, source durations, association with volcanoes in specific geodynamic environments, and the timing of the earthquakes relative to volcanic activity

Similarities and differences in the historical records of lava dome-building volcanoes: implications for understanding magmatic processes and eruption forecasting

A key question for volcanic hazard assessment is the extent to which information can be exchanged between volcanoes. This question is particularly pertinent to hazard forecasting for dome-building volcanoes, where effusive activity may persist for years to decades, and may be punctuated by periods of repose, and sudden explosive activity. Here we review historical eruptive activity of fifteen lava dome-building volcanoes over the past two centuries, with the goal of creating a hierarchy of exchangeable (i.e., similar) behaviours. Eruptive behaviour is classified using empirical observations that include patterns of SO2 flux, eruption style, and magma composition. We identify two eruptive regimes: (i) an episodic regime where eruptions are much shorter than intervening periods of repose, and degassing is temporally correlated with lava effusion; and (ii) a persistent regime where eruptions are comparable in length to periods of repose and gas emissions do not correlate with eruption rates. A corollary to these two eruptive regimes is that there are also two different types of repose: (i) inter-eruptive repose separates episodic eruptions, and is characterised by negligible gas emissions and (ii) intra-eruptive repose is observed in persistently active volcanoes, and is characterised by continuous gas emissions. We suggest that these different patterns of can be used to infer vertical connectivity within mush-dominated magmatic systems. We also note that our recognition of two different types of repose raises questions about traditional definitions of historical volcanism as a point process. This is important, because the ontology of eruptive activity (that is, the definition of volcanic activity in time) influences both analysis of volcanic data and, by extension, interpretations of magmatic processes. Our analysis suggests that one identifying exchangeable traits or behaviours provides a starting point for developing robust ontologies of volcanic activity. Moreover, by linking eruptive regimes to conceptual models of magmatic processes, we illustrate a path towards developing a conceptual framework not only for comparing data between different volcanoes but also for improving forecasts of eruptive activity

HASSET: A probability event tree tool to evaluate future volcanic scenarios using Bayesian inference

Event tree structures constitute one of the most useful and necessary tools in modern volcanology for assessment of hazards from future volcanic scenarios (those that culminate in an eruptive event as well as those that do not). They are particularly relevant for evaluation of long- and short-term probabilities of occurrence of possible volcanic scenarios and their potential impacts on urbanized areas. In this paper, we introduce Hazard Assessment Event Tree (HASSET), a probability tool, built on an event tree structure that uses Bayesian inference to estimate the probability of occurrence of a future volcanic scenario and to evaluate the most relevant sources of uncertainty from the corresponding volcanic system. HASSET includes hazard assessment of noneruptive and nonmagmatic volcanic scenarios, that is, episodes of unrest that do not evolve into volcanic eruption but have an associated volcanic hazard (e.g., sector collapse and phreatic explosion), as well as unrest episodes triggered by external triggers rather than the magmatic system alone. Additionally, HASSET introduces the Delta method to assess precision of the probability estimates, by reporting a 1 standard deviation variability interval around the expected value for each scenario. HASSET is presented as a free software package in the form of a plug-in for the open source geographic information system Quantum Gis (QGIS), providing a graphically supported computation of the event tree structure in an interactive and user-friendly way. We also include further in-depth explanations for each node together with an application of HASSET to Teide-Pico Viejo volcanic complex (Spain). © 2013 The Author(s).This work was supported by the European Commission (FP7 Theme: ENV.2011.1.3.3-1; grant 282759: VUELCO)Peer Reviewe

Buque de tipo catamarán auxiliar de acuicultura y factoría

En el presente proyecto se realizará la descripción, diseño y cálculo de un buque tipo “catamarán” fabricado en plástico reforzado con fibra de vidrio (P.R.F.V.) destinado a la producción, extracción y procesado de moluscos bivalvos tipo mejillón y similares. Con el fin de esclarecer si el presente proyecto es viable o no, tendremos que estudiar y evaluar una serie de factores que, después de su análisis, nos darán una visión clara de la situación del mercado mundial actual, de la demanda por parte de los consumidores de productos marinos y del riesgo que podemos correr a la hora de tomar la decisión de llevar a cabo dicho proyecto o no. Para todo ello, comenzaremos explicando el significado propio de la palabra “acuicultura” para posteriormente hacer un pequeño repaso de la historia y evolución del sector de la acuicultura no solo a nivel nacional, sino a nivel mundial. También veremos si dicho sector ha sufrido variaciones importantes, no sólo a nivel de demanda por parte del consumidor, sino que también tendremos que analizar otros factores que pueden influir a la hora de decidir llevar a cabo un proyecto de este tipo. Dentro de dichos factores podemos destacar el apoyo que hoy en día tienen los productores de especies marinas por parte de las Instituciones o los factores biológicos que influyen en el proceso de cultivo de los moluscos. No obstante, destacaremos que la realización de este estudio previo de viabilidad se puede aplicar a un sinfín de proyectos interesantes relacionados con la acuicultura y no sólo en este caso en particular. Puesto que el mundo de la ingeniería es tan amplio, lo son así también los proyectos de I+D+i que se pueden llevar a cabo en este sector. Cabe de esperar que al tratarse de un sector en auge, como veremos a continuación, los proyectos que se realizan son novedosos, punteros en diseño y “atractivos” para los constructores y propietarios que se aventuran poniendo todo su trabajo en darle mayor relevancia a dicho sector.Escuela Técnica Superior de Ingeniería Naval y OceánicaUniversidad Politécnica de Cartagen