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Purpose Using risk-related data often require a significant amount of upfront work to collect, extract and transform data. In addition, the lack of a consistent data structure hinders the development of tools that can be used with more than one set of data. The purpose of this paper is to report on an effort to solve these problems through the development of extensible, internally consistent schemas for risk-related data. Design/methodology/approach The consortia coordinated their efforts so the hazard, exposure and vulnerability schemas are compatible. Hazard data can be provided as either event footprints or stochastic catalogs. Exposure classes include buildings, infrastructure, agriculture, livestock, forestry and socio-economic data. The vulnerability component includes fragility and vulnerability functions and indicators for physical and social vulnerability. The schemas also provide the ability to define uncertainties and allow the scoring of vulnerability data for relevance and quality. Findings As a proof of concept, the schemas were populated with data for Tanzania and with exposure data for several other countries. Research limitations/implications The data schema and data exploration tool are open source and, if widely accepted, could become widely used by practitioners. Practical implications A single set of hazard, exposure and vulnerability schemas will not fit all purposes. Tools will be needed to transform the data into other formats. Originality/value This paper describes extensible, internally consistent, multi-hazard, exposure and vulnerability schemas that can be used to store disaster risk-related data and a data exploration tool that promotes data discovery and use.

Aluto is a peralkaline rhyolitic caldera located in a highly populated area in central Ethiopia. Its postcaldera eruptive activity has mainly consisted of self‐similar, pumice‐cone‐building eruptions of varying size and vent location. These eruptions are explosive, generating hazardous phenomena that could impact proximal to distal areas from the vent. Volcanic hazard assessments in Ethiopia and the East African Rift are still limited in number. In this study, we develop an event tree model for Aluto volcano. The event tree is doubly useful: It facilitates the design of a conceptual model for the volcano and provides a framework to quantify volcanic hazard. We combine volcanological data from past and recent research at Aluto, and from a tool to objectively derive analog volcanoes (VOLCANS), to parameterize the event tree, including estimates of the substantial epistemic uncertainty. Results indicate that the probability of a silicic eruption in the next 50 years is highly uncertain, ranging from 2% to 35%. This epistemic uncertainty has a critical influence on event‐tree estimates for other volcanic events, like the probability of occurrence of pyroclastic density currents (PDCs) in the next 50 years. The 90% credible interval for the latter is 5–16%, considering only the epistemic uncertainty in conditional eruption size and PDC occurrence, but 2–23% when adding the epistemic uncertainty in the probability of eruption in 50 years. Despite some anticipated challenges, we envisage that our event tree could be translated to other rift volcanoes, making it an important tool to quantify volcanic hazard in Ethiopia and elsewhere.

The definition of a suite of analogue volcanoes, or volcanoes that are considered to share enough characteristics as to be considered exchangeable to a certain extent, is becoming a key component of volcanic hazard assessment. This is particularly the case for volcanoes where data are lacking or scarce. Moreover, volcano comparisons have often been based on similarities and differences inferred through expert judgement and not necessarily informed by volcano characteristics from global datasets. These similarities can be based on a range of features, from very simplified (e.g. statrovolcanoes) to very specific (e.g. detailed eruption chronologies), and may be strongly influenced by the personal experience of individuals or teams conducting the analogue analysis. In this work, we present VOLCANS (VOLCano ANalogues Search)—an objective, structured and reproducible method to identify sets of analogue volcanoes from global volcanological databases. Five overarching criteria (tectonic setting, rock geochemistry, volcano morphology, eruption size and eruption style), and a structured combination of them, are used to quantify overall multi-criteria volcano analogy. This innovative method is complementary to expert-derived sets of analogue volcanoes and provides the user with full flexibility to weigh the criteria and identify analogue volcanoes applicable to varied purposes. Some results are illustrated for three volcanoes with diverse features and significant recent and/or ongoing eruptions: Kı̄lauea (USA), Fuego (Guatemala) and Sinabung (Indonesia). The identified analogue volcanoes correspond well with a priori analogue volcanoes derived from expert knowledge. In some cases, single-criterion searches may not be able to isolate a reduced set of analogue volcanoes but any multi-criteria search can provide high degrees of granularity in the sets of analogue volcanoes obtained. Data quality and quantity can be important factors, especially for single-criterion searches and volcanoes with very scarce data (e.g. Sinabung). Nevertheless, the method gives stable results overall across multi-criteria searches of analogue volcanoes. Potential uses of VOLCANS range from quantitative volcanic hazard assessment to promoting fundamental understanding of volcanic processes.

We summarize major findings and best-practice recommendations from three Volcano Observatory Best Practices (VOBP) workshops, which were held in 2011, 2013 and 2016. The workshops brought together representatives from the majority of the world’s volcano observatories for the purpose of sharing information on the operation and practice of these institutions and making best practice recommendations. The first workshop focused on eruption forecasting, the second on hazard communication, and the third on long-term hazard assessment. Subsequent VOBP workshops will address additional issues of broad interest to the international volcano observatory community. The objective of VOBP is to develop synergy among volcano hazards programs and their observatories internationally, so as to more rapidly and broadly advance the field of applied volcanology. Each of the workshop summaries presented here include best practice recommendations for consideration by the world’s volcano observatories.

Volcanoes are hazardous to local and global populations, but only a fraction are continuously monitored by ground‐based sensors. For example, in Latin America, more than 60% of Holocene volcanoes are unmonitored, meaning long‐term multiparameter data sets of volcanic activity are rare and sparse. We use satellite observations of degassing, thermal anomalies, and surface deformation spanning 17 years at 47 of the most active volcanoes in Latin America and compare these data sets to ground‐based observations archived by the Global Volcanism Program. This first comparison of multisatellite time series on a regional scale provides information regarding volcanic behavior during, noneruptive, pre‐eruptive, syneruptive, and posteruptive periods. For example, at Copahue volcano, deviations from background activity in all three types of satellite measurements were manifested months to years in advance of renewed eruptive activity in 2012. By quantifying the amount of degassing, thermal output, and deformation measured at each of these volcanoes, we test the classification of these volcanoes as open or closed volcanic systems. We find that ~28% of the volcanoes do not fall into either classification, and the rest show elements of both, demonstrating a dynamic range of behavior that can change over time. Finally, we recommend how volcano monitoring could be improved through better coordination of available satellite‐based capabilities and new instruments.

Hazardous sequences of vulcanian explosions are thought to result from the repeated emplacement and destruction of degassed, highly crystalline magma plugs in the shallow conduit of arc volcanoes. The processes governing the timing and magnitude of these explosions are thought to be related to magma ascent rate and efficiency of degassing and crystallisation. We study a rare suite of time-constrained ballistic bombs from the 2004–2010 period of activity of Galeras volcano to reconstruct magma plug architecture prior to six individual vulcanian explosions. We find that each plug was vertically stratified with respect to crystallinity, vesicularity and melt volatile content, melt composition and viscosity. We interpret this structure as resulting from multiple bubble nucleation events and degassing-driven crystallisation during multi-step ascent of the magma forming the plug, followed by spatially variable crystallisation within the plug under contrasting conditions of effective undercooling created by degassing. We propose that the shallow conduit evolved from more open degassing conditions during 2004–2008 to more closed conditions during 2009–2010. This resulted in explosions becoming smaller and less frequent over time during 2004–2008, then larger and more frequent over time during 2009–2010. This evolution was controlled by changing average ascent rates and is recorded by systematic changes in plagioclase microlite textures. Our results suggest that small volume vulcanian explosions (~ 105 m3) should generally be associated with longer repose times (hundreds of days) and produce ballistics characterised by small numbers of large, prismatic plagioclase microlites. Larger volume vulcanian explosions (~ 106 m3) should be associated with shorter repose times (tens of days) and produce ballistics characterised by high numbers of small, more tabular plagioclase microlites. Electronic supplementary material The online version of this article (10.1007/s00445-018-1260-y) contains supplementary material, which is available to authorized users.

Collaborative research projects have a significant role in filling the knowledge gaps that are obstacles to the rigorous assessment of volcanic hazards in some locations. Research is essential to generate the evidence on which raising awareness of volcanic hazards, monitoring and early warning systems, risk reduction activities and efforts to increase resilience can be built. We report the current state of volcanic hazards research and practice in Ethiopia and on the collaborative process used in the Afar Rift Consortium project to promote awareness of volcanic hazards. Effective dissemination of findings to stakeholders and the integration of results into existing practice need leadership by in-country researchers, effective long-term collaboration with other researchers (e.g. international groups) and operational scientists, in addition to integration with existing programmes related to disaster risk reduction initiatives.

The recovery process unfolds over a long time and can last for decades, yet most studies of recovery are over short timeframes or represent points in time across the process. Long-term disaster recovery studies are necessary in order to understand the process and the changes that are promoted by disasters over many years. Retrospective methods offer opportunities to gather a dataset of changes over long periods of time, yet concerns with the reliability of participant recall create challenges for research. Retrospective studies need improved data gathering techniques to facilitate reliable recall. This paper documents the use of an inductive timeline in a retrospective study of disaster recovery for the healthcare system in Montserrat, West Indies. Drawing on creative approaches in the literature we developed a timeline tool for use within focus group settings. We conducted four focus groups with healthcare staff in 2011 (n=7, n=8, n=6 and n=7) to gather retrospective data over the extended period of the eruption of Soufriere Hills Volcano (episodic since 1995). The approach yielded rich empirical data of changes to the healthcare system observed by the participants over time. Triangulating the results with secondary data (where available) and interviews demonstrated excellent participant recall using this technique. This approach potentially opens-up a field of study in long-term disaster recovery for historical events or cases where poor records have limited their study to date. Further applications could include study of long-term change processes in different social and environmental contexts.

How a volcano has behaved throughout its past is a guide to its future behaviour. Detailed knowledge of what preceded eruptions from specific volcanoes, and how this can be recognised in real-time, are pivotal questions of this field. Here, the physical history of the magma that erupted in 2010 from the flank of Eyjafjallajökull volcano, Iceland, is reconstructed in absolute time and space using only chemical records from erupted crystals. The details of this reconstruction include the number of magma bodies, their geometry, their depth, their relative inflation rate and changes to all of the aforementioned through time. Petrology and geodesy (data gathered in real-time) arrive at the same set of conclusions. As such, we report detailed agreement, which demonstrates a causative link between knowledge determined post-eruption via a physical–chemical perspective and knowledge gained syn-eruption from monitoring signals. The composition of olivine crystal cores (∼Fo74–87), and that of the chemical zonation around each core caused by disequilibrium processes, are shown to form systematic patterns at the population scale. Reverse zonation (toward Mg rich) exhibits a constant chemical offset from its crystal core (≤2 mol % Fo), while normal zonation (toward Fe rich) converges to a single composition (∼Fo75). Conventional petrological models — for instance multiple-magma-mixing across a range of crustal depths — can explain the presence of a range of crystal core composition in the erupted rocks, but cannot explain these patterns of crystal disequilibria. Instead, we describe how a single primitive melt produces crystals over a wide range in composition and generates systematic disequilibrium. Cooling causes crystal production from both roof and floor of a horizontal magma geometry. Crystal settling causes asymmetric thermal – and therefore compositional – stratification of the melt due to progressive insulation via development of a crystal mush at the floor, a process we term “Crystal Rain”. Crucially, each crystal's record is both a cause and effect of the internal process of simultaneous fractional crystallisation and settling; no external processes or materials are required. We then extract temporal information from our crystals using Fe–Mg interdiffusion modelling, and combine it with the composition and zonation data. The concept of Crystal Rain is applied, and resolves two thin (metres) sills which are staggered in time and depth, and exhibit different inflation rates. Since the approach of integrating crystal chronology within a causative physical framework may be applied to entire volcanic successions, it has potential to yield valuable insights to past, and by inference future, magmatic and volcanic behaviours by deterministic means., This study was started under the remit of NERC grant NE/J024554/1 to DJM, TT, and SL, upon which MJP was the PDRA. Completion of the study occurred during an AXA Research Fund Fellowship awarded to MJP.

Long-term volcanic activity at Soufriere Hills Volcano (SHV), Montserrat (1995–ongoing) has created challenges for society and the resilience of the essential services (infrastructure) that support it. This paper explores the consequences, adaptations and resilience of essential services through interviews with their staff. We find that quick fixes for essential service reinstatement in the north of Montserrat have prevailed. Yet, the legacy of this approach inhibits functionality through inadequate facilities and the perception of sites as temporary, stalling investment. Emigration resulted in staff shortages, retraining requirements and challenges for the viability of specialist services. Low-impact hazards exacerbate shortcomings in essential services, causing power cuts, corrosion, and temporary closures of schools, clinics and the airport. Adaptations developed over time include changes to roofing materials, the addition of back-up systems, collaborative working and the development of contingency plans. Resilience of essential services has improved through decentralization, adaptations, and via strong community networks and tolerance of disruptions. Barriers to increasing resilience include the expense of some adaptations and the current reluctance to invest in essential services, hindering development. We offer some lessons for policy and practice to guide post-crisis redevelopment, through engagement with the community and by complementing community-level adaptations with investment to address long-term needs.

This paper describes ash-venting activity at Soufriere Hills Volcano, Montserrat that was precursory to the onset of three phases of lava extrusion in 2005, 2008 and 2009, and similar ash venting that occurred during the fifth phase of lava extrusion. We describe in detail a style of mild, tephra-generating activity termed ash venting and its associated tephra products. The nature of the seismicity associated with ash venting is compared with that of explosive activity. All explosive events, from small explosions to large Vulcanian explosions, have impulsive, low-frequency onsets. These are absent in ash-venting events, which have subtle, emergent onsets. Microscope and grain-size analyses show that ash-venting events and large Vulcanian explosions generate tephra that is similar in grain size (in medial and distal regions), although phreatic events in 2005 were finer grained. Ash-venting products are either composed of fine-grained, variably altered pre-existing material or juvenile material. There is a general correlation between the length of the pause and the length of the period of precursory activity prior to lava extrusion following it. Syn-extrusive ash venting is frequently associated with short-term increases in extrusion rate and is considered to be related to shear-induced fragmentation at the conduit margin.

More than 30 years after the first major aircraft encounters with volcanic ash over Indonesia in 1982, it remains challenging to inform aircraft in flight of the exact location of potentially dangerous ash clouds on their flight path, particularly shortly after the eruption has occurred. The difficulties include reliably forecasting and detecting the onset of significant explosive eruptions on a global basis, observing the dispersal of eruption clouds in real time, capturing their complex structure and constituents in atmospheric transport models, describing these observations and modelling results in a manner suitable for aviation users, delivering timely warning messages to the cockpit, flight planners and air traffic management systems, and the need for scientific development in order to undertake operational enhancements. The framework under which these issues are managed is the International Airways Volcano Watch (IAVW), administered by the International Civil Aviation Organization (ICAO). ICAO outlines in its standards and recommended practices (International Civil Aviation Organization 2014a, b) the basic volcanic monitoring and communication that is necessary at volcano observatories in Member States (countries). However, not all volcanoes are monitored and not all countries with volcanoes have mandated volcano observatories or equivalents. To add to the efforts of volcano observatories, a system of Meteorological Watch Offices, Air Traffic Management Area Control Centres, and nine specialist Volcanic Ash Advisory Centres (VAACs) are responsible for observing, analysing, forecasting and communicating the aviation hazard (airborne ash), using agreed techniques and messages in defined formats. Continuous improvement of the IAVW framework is overseen by expert groups representing the operators of the system, the user community, and the science community. The IAVW represents a unique marriage of two scientific disciplines, volcanology and meteorology, with the aviation user community. There have been many multifaceted volcanic eruptions in complex meteorological conditions during the history of the IAVW. Each new eruption brings new insights into how the warning system can be improved, and each reinforces the lessons that have gone before. The management of these events has improved greatly since the major ash encounters in the 1980s, but discontinuities in the warning and communications system still occur. A good example is a 2014 ash encounter over Indonesia following the eruption of Kelut where the warnings did not reach the aircraft crew. Other events present enormous management challenges—for example the 2010 Eyjafjallajokull eruption in Iceland was, overall, less hazardous than many less publicised eruptions, but numerous small to moderate explosions over several weeks produced widespread disruption and a large economic impact. At the time of writing, while there has been hundreds of millions of US dollars in damage to aircraft from encounters with ash, there have been no fatalities resulting from aviation incidents in, or proximal to volcanic ash cloud. This reflects, at least in part, the hard work done in putting together a global warning system—although to some extent it also reflects a measure of good statistical fortune. In order to minimise the risk of aircraft encounters with volcanic ash clouds, the global effort continues. The future priorities for the IAVW are strongly focused on enhancing communication before, and at the very onset of a volcanic ash-producing event (typically the more dangerous stage), together with improved downstream information and warning systems to help reduce the economic impact of eruptions on aviation.

Explosive volcanic eruptions are complex systems that can generate a variety of hazardous phenomena, for example, the injection of volcanic ash into the atmosphere or the generation of pyroclastic density currents. Explosive eruptions occur when a turbulent multiphase mixture, initially predominantly composedf of fragmented magma and gases, is injected from the volcanic vent into the atmosphere. For plume modelling purposes, a specific volcanic eruption scenario based on eruption type, style or magnitude is strictly linked to magmatic and vent conditions, despite the subsequent evolution of the plume being influenced by the interaction of the erupted material with the atmosphere. In this chapter, different methodologies for investigating eruptive source conditions and the subsequent evolution of the eruptive plumes are presented. The methodologies range from observational techniques to large-scale experiments and numerical models. Results confirm the relevance of measuring and observing source conditions, as such studies can improve predictions of the hazards of eruptive columns. The results also demonstrate the need for fundamental future research specifically tailored to answer some of the still open questions: the effect of unsteady flow conditions at the source on the eruptive column dynamics and the interaction between a convective plume and wind.

The historically active volcanic ocean island of Tristan da Cunha exhibits a complex and dynamic history, with numerous, often compositionally distinct, parasitic centers punctuating the large edifi ce. To date, the temporal relationship between differing styles of activity has been unclear. We have applied high-precision 40Ar/39Ar dating to 15 carefully selected samples from Tristan da Cunha to ascertain spatio-temporal relationships of recent volcanism, explore episodicity, and establish if the most recent summit activity post-dated eruptions from parasitic centers lower on the fl anks. This has yielded a new suite of reliable Holocene ages, with the youngest dated deposit at 3 ± 1 ka (1σ). A recent fl ow at the summit was constrained to 5 ± 1 ka (1σ), confi rming that summit and parasitic activity on the volcano’s fl anks overlap in time. The oldest dated deposits were 118 ± 4 ka (1σ) from a parasitic cone in the southern sector, and 81 ± 10 ka (1σ) from one of the lowest sub-aerial shield-forming lava fl ows in the northern sector. Large-scale sector collapse is bracketed between 34 ± 1 ka and 26 ± 5 ka (1σ) via dating of the youngest headwall lava fl ow and oldest sub-aerial scarp-fi lling deposits. No systematic relationship between the new temporal framework, vent location, and eruptive compositions was found. Although magmatic fl ux has been inferred to be relatively low, Tristan da Cunha is capable of relatively frequent eruptions from a wide variety of vent locations across a broad range of compositions.

The 20th May 2006 lava dome collapse of the Soufrière Hills Volcano, Montserrat, had a total non-dense rock equivalent (non-DRE) collapse volume of approximately 115 × 106 m3. The majority of this volume was deposited into the ocean. The collapse was rapid, 85% of the mobilized volume being removed in just 35 min, giving peak pyroclastic flow flux of 66 × 103 m3 s−1. Channel and levee facies on the submarine flanks of the volcano and formation of a thick, steep-sided ridge, suggest that the largest and most dense blocks were transported proximally as a high concentration granular flow. Of the submerged volume, 30% was deposited from the base of this granular flow, forming a linear, high-relief ridge that extends 7 km from shore. The remaining 70% of the submerged volume comprises the finer grain sizes, which were transported at least 40 km by turbidity currents on gradients of

The eruptions of the Soufrière Hills volcano on Montserrat (Lesser Antilles) from 1995 to present have draped parts of the island in fresh volcaniclastic deposits. Volcanic islands such as Montserrat are an important component of global weathering fluxes, due to high relief and runoff and high chemical and physical weathering rates of fresh volcaniclastic material. We examine the impact of the recent volcanism on the geochemistry of pre-existing hydrological systems and demonstrate that the initial chemical weathering yield of fresh volcanic material is higher than that from older deposits within the Lesser Antilles arc. The silicate weathering may have consumed 1.3% of the early CO2 emissions from the Soufrière Hills volcano. In contrast, extinct volcanic edifices such as the Centre Hills in central Montserrat are a net sink for atmospheric CO2 due to continued elevated weathering rates relative to continental silicate rock weathering. The role of an arc volcano as a source or sink for atmospheric CO2 is therefore critically dependent on the stage it occupies in its life cycle, changing from a net source to a net sink as the eruptive activity wanes. While the onset of the eruption has had a profound effect on the groundwater around the Soufrière Hills center, the geochemistry of springs in the Centre Hills 5 km to the north appear unaffected by the recent volcanism. This has implications for the potential risk, or lack thereof, of contamination of potable water supplies for the island’s inhabitants.

On 20th May 2006 the Soufrière Hills Volcano on the Caribbean island of Montserrat experienced a large dome collapse and intense rainfall generated flash floods. The floods had very high loads of volcanic debris derived both from this and previous eruptions and can thus be classified as lahars. The floods reached unusually high water levels and caused substantial geomorphic change in the Belham Valley. Detailed rainfall and geomorphological data, coupled with the precise timing of events and yewitness accounts have facilitated an assessment of the relative importance of rainfall volume and intensity, older volcanic debris, pre- and syn-flood tephra fall and the extent of pre-flood vegetation damage for the behavior of this and subsequent sediment-laden floods in this setting. The change in runoff behavior was controlled by preexisting vegetation damage and synchronous tephra fall and this was critically important in controlling the impact of these flash floods. Although rainfall intensity and volume have some control on flood occurrence they are not the critical control on flash flood impact on the geomorphology in the Belham Valley. A significant conclusion of this study is that the extreme nature of the flash floods was not caused by extreme rainfall (as is commonly believed to be the primary cause of flash floods) but rather it was the result of changed runoff behaviour caused by the widespread syn-flood tephra deposition and importantly the widespread vegetation damage by volcanic-associated acid rain in the preceding weeks.

The Lewisian Gneiss Complex of northwestern Scotland consists of Archaean gneisses, variably reworked during the Proterozoic. It can be divided into three districts – a central granulite-facies district between districts of amphibolite-facies gneiss to the north and south. Recent work has interpreted these districts in terms of separate terranes, initiating a controversy that has implications for how Precambrian rocks are understood worldwide. The northern district of the Lewisian Gneiss Complex (the Rhiconich terrane) is separated from the central district (the Assynt terrane) by a broad ductile shear zone known as the Laxford Shear Zone. This paper reviews the geology of the Laxford Shear Zone, clarifying field relationships and discussing other evidence, to consider whether or not it does indeed represent a terrane boundary. A detailed review of field, geochemical and geochronological evidence supports the recognition of the separate Assynt and Rhiconich terranes. Mafic dykes (the Scourie Dyke Swarm) and granitoids, of Palaeoproterozoic age, occur on both sides of the Laxford Shear Zone and thus the terranes were most probably juxtaposed during the late Archaean to early Palaeoproterozoic Inverian event. Subsequently, the less-competent, more-hydrous amphibolite-facies gneisses of the Rhiconich terrane were affected by later Palaeoproterozoic (Laxfordian) deformation and partial melting, to a greater extent than the more-competent granulite-facies gneisses of the Assynt terrane.

The Africa–Arabia plate boundary comprises the Red Sea oceanic spreading centre and the left-lateral Dead Sea Fault Zone (DSFZ); however, previous work has indicated kinematic inconsistency between its continental and oceanic parts. The Palmyra Fold Belt (PFB) splays ENE from the DSFZ in SW Syria and persists for ∼400 km to the River Euphrates, but its significance within the regional pattern of active crustal deformation has hitherto been unclear. We report deformation of Euphrates terraces consistent with Quaternary right-lateral transpression within the PFB, indicating anticlockwise rotation (estimated as 0.3° Ma−1 about 36.0°N 39.8°E) of the block between the PFB and the northern DSFZ relative to the Arabian Plate interior. The northern DSFZ is shown to be kinematically consistent with the combination of Euler vectors for the PFB and the Red Sea spreading, resolving the inconsistency previously evident. The SW PFB causes a significant earthquake hazard, previously unrecognized, to the city of Damascus.

During many lava dome-forming eruptions, persistent rockfalls and the concurrent development of a substantial talus apron around the foot of the dome are important aspects of the observed activity. An improved understanding of internal dome structure, including the shape and internal boundaries of the talus apron, is critical for determining when a lava dome is poised for a major collapse and how this collapse might ensue. We consider a period of lava dome growth at the Soufriere Hills Volcano, Montserrat, from August 2005 to May 2006, during which a similar to 100 x 10(6) m(3) lava dome developed that culminated in a major dome-collapse event on 20 May 2006. We use an axi-symmetrical Finite Element Method model to simulate the growth and evolution of the lava dome, including the development of the talus apron. We first test the generic behaviour of this continuum model, which has core lava and carapace/talus components. Our model describes the generation rate of talus, including its spatial and temporal variation, as well as its post-generation deformation, which is important for an improved understanding of the internal configuration and structure of the dome. We then use our model to simulate the 2005 to 2006 Soufriere Hills dome growth using measured dome volumes and extrusion rates to drive the model and generate the evolving configuration of the dome core and carapace/talus domains. The evolution of the model is compared with the observed rockfall seismicity using event counts and seismic energy parameters, which are used here as a measure of rockfall intensity and hence a first-order proxy for volumes. The range of model-derived volume increments of talus aggraded to the talus slope per recorded rockfall event, approximately 3 x 10(3) - 13 x 10(3) m(3) per rockfall, is high with respect to estimates based on observed events. From this, it is inferred that some of the volumetric growth of the talus apron (perhaps up to 60-70%) might have occurred in the form of aseismic deformation of the talus, forced by an internal, laterally spreading core. Talus apron growth by this mechanism has not previously been identified, and this suggests that the core, hosting hot gas-rich lava, could have a greater lateral extent than previously considered. (C) 2009 Elsevier B.V. All rights reserved.

Two domains have previously been recognized in the Archaean Reguibat Shield of NW Mauritania, based primarily on their gross lithological differences (Rocci et al., 1991). New fieldwork has identified a major ductile shear zone (Tâcarât -Inemmaudene Shear Zone) se-parating these domains and new geochronological studies show that the two domains record different Mesoarchaean histories. As such, the two domains are redefined as the Choum-Rag el Abiod Terrane and Tasiast-Tijirit Terrane. Previous isotopic studies of metamorphic litholo-gies of the eastern Choum-Rag el Abiod Terrane indicate a succession of crustal growth from about 3.5-3.45 Ga to between about 3.2 and 2.99 Ga. Isotopic data presented in this contribu-tion from the Tasiast-Tijirit Terrane indicate that emplacement of major calc-alkaline plutons occurred at c.2.93 Ga after volcanism (preserved as greenstone belts) that included late felsic eruptive centres dated at c.2965 Ma. This Mesoarchaean intrusive and extrusive magmatism was confined to the Tasiast-Tijirit Terrane where it was emplaced through migmatitic or-thogneisses that are the oldest lithodemic unit of the Tasiast-Tijirit Terrane. Widespread bi-modal, post-tectonic magmatism in both terranes included major granitic magmatism dated at c.2730 Ma. The N- to NNE-trending curvilinear Tâcarât -Inemmaudene Shear Zone that separates the two terranes records late intense transpressive ductile shearing. It has a flower structure over a horizontal distance of about 70 km across its southern portion with unquantifiable sinistral horizontal offset, and east-directed thrusting on its eastern side where it cuts into the Choum-Rag el Abiod Terrane. A new U-Pb zircon age of 2954±11 Ma is presented for a deformed granite confined within the central part of this shear zone. A minimum age for the shearing is provided by a previously determined c. 2.73 Ga age for a post-tectonic granite that cuts across the easternmost part of the shear zone in the Choum-Rag el Abiod Terrane.

1. An introduction to global volcanic hazard and risk S. C. Loughlin, C. Vye-Brown, R. S. J. Sparks, S. K. Brown, J. Barclay, E. Calder, E. Cottrell, G. Jolly, J.-C. Komorowski, C. Mandeville, C. Newhall, J. Palma, S. Potter, G. Valentine, B. Baptie, J. Biggs, H. S. Crosweller, E. Ilyinskaya, C. Kilburn, K. Mee and M. Pritchard 2. Global volcanic hazard and risk S. K. Brown, S. C. Loughlin, R. S. J. Sparks, C. Vye-Brown, J. Barclay, E. Calder, E. Cottrell, G. Jolly, J.-C. Komorowski, C. Mandeville, C. Newhall, J. Palma, S. Potter, G. Valentine, B. Baptie, J. Biggs, H. S. Crosweller, E. Ilyinskaya, C. Kilburn, K. Mee and M. Pritchard 3. Volcanic ash fall hazard and risk S. F. Jenkins, T. M. Wilson, C. Magill, V. Miller, C. Stewart, R. Blong, W. Marzocchi, M. Boulton, C. Bonadonna and A. Costa 4. Populations around Holocene volcanoes and development of a Population Exposure Index S. K. Brown, M. R. Auker and R. S. J. Sparks 5. An integrated approach to Determining Volcanic Risk in Auckland, New Zealand: the multidisciplinary DEVORA project N. I. Deligne, J. M. Lindsay and E. Smid 6. Tephra fall hazard for the Neapolitan area W. Marzocchi, J. Selva, A. Costa, L. Sandri, R. Tonini and G. Macedonio 7. Eruptions and lahars of Mount Pinatubo, 1991-2000 C. G. Newhall and R. Solidum 8. Improving crisis decision-making at times of uncertain volcanic unrest (Guadeloupe, 1976) J.-C. Komorowski, T. Hincks, R. S. J. Sparks, W. Aspinall and CASAVA ANR project consortium 9. Forecasting the November 2010 eruption of Merapi, Indonesia J. Pallister and Surono 10. The importance of communication in hazard zone areas: case study during and after 2010 Merapi eruption, Indonesia S. Andreastuti, J. Subandriyo, S. Sumarti and D. Sayudi 11. Nyiragongo (Democratic Republic of Congo), January 2002: a major eruption in the midst of a complex humanitarian emergency J.-C. Komorowski and K. Karume 12. Volcanic ash fall impacts T. M. Wilson, S. F. Jenkins and C. Stewart 13. Health impacts of volcanic eruptions C. Horwell, P. Baxter and R. Kamanyire 14. Volcanoes and the aviation industry P. W. Webley 15. The role of volcano observatories in risk reduction G. Jolly 16. Developing effective communication tools for volcanic hazards in New Zealand, using social science G. Leonard and S. Potter 17. Volcano monitoring from space M. Poland 18. Volcanic unrest and short-term forecasting capacity J. Gottsmann 19. Global monitoring capacity: development of the Global Volcano Research and Monitoring Institutions Database and analysis of monitoring in Latin America N. Ortiz Guerrero, S. K. Brown, H. Delgado Granados and C. Lombana Criollo 20. Volcanic hazard maps E. Calder, K. Wagner and S. E. Ogburn 21. Risk assessment case history: the Soufriere Hills Volcano, Montserrat W. Aspinall and G. Wadge 22. Development of a new global Volcanic Hazard Index (VHI) M. R. Auker, R. S. J. Sparks, S. F. Jenkins, S. K. Brown, W. Aspinall, N. I. Deligne, G. Jolly, S. C. Loughlin, W. Marzocchi, C. G. Newhall and J. L. Palma 23. Global distribution of volcanic threat S. K. Brown, R. S. J. Sparks and S. F. Jenkins 24. Scientific communication of uncertainty during volcanic emergencies J. Marti 25. Volcano Disaster Assistance Program: preventing volcanic crises from becoming disasters and advancing science diplomacy J. Pallister 26. Communities coping with uncertainty and reducing their risk: the collaborative monitoring and management of volcanic activity with the Vigias of Tungurahua J. Stone, J. Barclay, P. Ramon, P. Mothes and STREVA.

Investigation of the global eruptive records of particular types of volcanoes is a fundamental and valuable method of understanding what style of activity can be anticipated in the future and can highlight what might be expected or unusual in particular settings. This paper investigates the relationship between large explosions (volcanic explosivity index, VEI ≥ 4) and lava dome growth from 1000 AD to present and develops the DomeHaz database. DomeHaz contains information from 397 dome-forming episodes, including duration of dome growth, duration of pauses in extrusion, extrusion rates, and the timing and magnitude (VEI) of associated large explosions. Major explosive activity, when associated with dome growth, is more likely to occur before dome growth rather than during, or at the end of, dome-forming eruptions. In most cases where major explosive activity has been associated with dome growth, the eruptions occurred at basaltic andesite to andesitic volcanoes (the most common type of dome-forming volcano), but a greater proportion of dacitic and rhyolitic dome growth episodes were associated with large explosions. High extrusion rates (>10 m3 s−1) seem to be associated with large explosions and may inhibit degassing or destabilize existing domes, leading to explosive decompression. Large explosions may, alternatively, be followed by dome growth, which represents the clearing of residual magma from the conduit. Relationships extracted from the global record can be used to construct probability trees for new and ongoing dome-forming eruptions or can be used in conjunction with other types of event trees to aid in forecasting volcanic hazards during a crisis, especially for volcanoes where data are sparse.

A new lithostratigraphic nomenclatural framework is proposed for the Anti-Atlas Orogen of Morocco, to replace the previous chronostratigraphic scheme. All the lithostratigraphic units of the Anti-Atlas Orogen are well represented in the Sirwa, Kerdous and Sarhro inliers and examples from these areas are given prominence, though correlates in other areas are given, where known. The oldest, Palaeoproterozoic, rocks of the cratonic basement form the northern part of the West African Craton and can be subdivided into a series of Complexes (made up of constituent Groups, Suites etc.), depending on geographical outcrop (e.g. the Zenaga and Kerdous Complexes in the Sirwa and Kerdous inliers respectively). The Neoproterozoic rocks deposited on this basement are termed the Anti-Atlas Supergroup , within which five groups of volcano–sedimentary units ( Taghdout , Jbel Lkst , Sarhro , Iriri , and Bou Azzer Groups ) and various intrusive igneous rocks are recognised (e.g. Ifzwane and Toudma Suites ). These units are related to the earliest passive margin, oceanic and island-arc development phases of the orogen between ∼800 and 660 Ma. The earliest Pan-African deformation (at ∼660 Ma) resulted from closure of the ocean basin, SW-directed thrusting and accretion of the island-arc remnants. Continued prolonged convergence gave rise to a sinistral transpressional regime in which late syn- to post-tectonic continental volcanic and clastic sequences of the Ouarzazate Supergroup were deposited. The first rocks of this new tectonic regime were deposited in narrow, tectonically active, strike-slip pull-apart rift basins ( Bou Salda , Mgouna , Tafrawt and Anzi Groups ) associated with intrusion of high-K calc-alkaline granitoid batholiths (e.g. Assarag , Bardouz Suites ) and the juxtaposition of ophiolitic remnants in major strike-slip shear belts. These were followed by the deposition of the much more areally extensive continental volcano–sedimentary molasse, the volcanic components of which were erupted from several interfingering volcanic centres, often associated with caldera complexes and sub-volcanic alkaline granites ( Toufhgrane , Tanghourt and Guellaba Suites ). The proposed lithostratigraphic scheme encompasses all the major rock units identified in the literature from the orogen and is flexible so that new, lower-ranking, units can be placed at the appropriate stratigraphic level in future. This framework is supported by new high-precision U–Pb zircon dates that have recently become available.

The geochemical evolution of Montserrat provides an important background to understanding the current activity of this island arc volcano. Here we present major and trace element, and U-, Thand O-isotope data for rocks generated in the last 300 kyr that provide constraints on the magmatic processes occurring beneath the volcano. Samples range from lowto medium-K calc-alkaline basalts to dacites. Three suites can be distinguished on the basis of major and trace element compositions: the South Soufri ere Hills suite; the Soufri ere Hills suite, including the lava from the current eruption; and the mafic inclusions. Magmatic differentiation of the magma that crystallized to form the mafic inclusions appears to have been governed by closed-system processes, modelled by fractional crystallization (F 0 32), whereas the mafic South Soufri ere Hills suite evolved in an open system, modelled by continuous magma recharge into a crystallizing reservoir (F 0 7). The Soufri ere Hills andesite compositions are attributed to crystal fractionation of the South Soufri ere Hills magmas; however, matrix glass compositions fall on a different trend, consistent with partial melting before eruption. Whole-rock dO values range from 7 0 to 7 4%, and are, therefore, slightly enriched compared with primitive arc lavas. This might be due to magmatic fractionation, or the assimilation of up to 20% hydrothermally altered arc crust. Extremely low Nb/Th ratios and low (Th/ Th) ratios compared with depleted mantle, and relatively high but constant Nd/Nd ratios indicate that the magma source beneath Montserrat is enriched by small ( 1 2%) amounts of sediment, which was added from the subducting slab probably as a partial melt. High U/Th ratios and large ion lithophile element abundances relative to local sediments suggest that fluid-mobile elements from the dehydrating slab were also added to the wedge, and that the fluid signature in the South Soufri ere Hills samples is stronger than in the mafic inclusions. U±Th isotopes are close to secular equilibrium, suggesting that the transfer time of the fluid signature from source to surface is 350 ka. In conjunction with evidence for magma remobilization at Montserrat, much of this time may represent crustal residence, suggesting long time scales of deeplevel differentiation relative to the inferred rapid crystallization at shallower levels.

Background Globally, more than 800 million people live in areas that have the potential to be affected by volcanic hazards, and this number is growing [Chapter 4]. The need for informed judgements regarding the global extent of potential volcanic hazards and the relative threats is therefore more pressing than ever. There is also an imperative to identify areas of relatively high hazard where studies and risk reduction measures may be best focussed. Various authors have tackled this task at a range of spatial scales, using a variety of techniques. At some well-studied volcanoes, the geological record has been used in combination with numerical modelling to create probabilistic hazard maps of volcanic flows and tephra fall [Chapter 6 and 20]. Such sources of information can be hugely beneficial in land use planning during times of quiescence and in emergency planning during times of unrest. Unfortunately, creating high-resolution probabilistic hazard maps for all volcanoes is not yet feasible. There is therefore a need for a methodology for volcanic hazard assessment that can be applied universally and consistently, which is less data-and computing-intensive. The aim of such an approach is to identify, on some objective overall basis, those volcanoes that pose the greatest danger, in order that more indepth investigations and disaster risk reduction efforts can then be focused on them. Previous methods An index-based approach to volcanic hazard assessment involves assigning scores to a series of indicators, which are then combined to give an overall hazard score. Indicators typically include measures of the frequency of eruptions, the relative occurrence of different kinds of eruptions and their related hazards, the footprints of these hazards, and eruption size. Indices are well suited to the problem of volcanic hazard assessment, as they allow the decomposition of the complex system into a suite of volcanic system controls and simple quantitative variables and factors that jointly characterise threat potential. Ewert (2007) presented an index-based methodology for assessing volcanic threat (the combination of hazard and exposure) in the USA, to permit prioritisation of research, monitoring and mitigation.

Gravitational collapses of the lava dome at Soufriere Hills Volcano on 25 June and 26 December 1997 generated pyroclastic surges that spread out over broad sectors of the landscape and laid down thin, bipartite deposits. In each case, part of the settling material continued to move upon reaching the ground and drained into valleys as high-concentration granular flows of hot (120-410°C) ash and lapilli. These surge-derived pyroclastic flows travelled at no more than 10 m s -1 but extended significantly beyond the limits of the parent surge clouds (by 3 km on 25 June and by 1 km on 26 December). The front of the 25 June flow terminated in a valley about 50 m below a small town that was occupied at the time. Despite their small deposit volumes (5-9 x 10 4 m 3 ), the surge-derived pyroclastic flows travelled as far as many of the Soufriere Hills block-and-ash flows on slopes as low as a few degrees, reflecting a high degree of mobility. An analysis of the deposits from 26 December suggests that sediment accumulation rates of at least several millimetres per second were sufficient to generate pyroclastic flows by suspended-load fallout from pyroclastic surges on Montserrat. Surge-derived pyroclastic flows are an important, and hitherto underestimated, hazard around active lava domes. At Montserrat they formed by sedimentation over large catchment areas and drained into valleys different from those affected by the primary block-and-ash flows and pyroclastic surges, thereby impacting areas not anticipated to be vulnerable in prior hazards analyses. The deposits are finer-grained than those of other types of pyroclastic flow at Soufriere Hills Volcano; this may aid their recognition in ancient volcanic successions but, along with valley-bottom confinement, reduces the preservation potential.

Four mechanisms caused tephra fallout at Soufriere Hills Volcano, Montserrat, during the 1995-1999 period: explosive activity (mainly of Vulcanian type), dome collapses, ash-venting and phreatic explosions. The first two mechanisms contributed most of the tephra-fallout deposits (minimum total dense-rock equivalent volume of 23 x 10 6 m 3 ), which vary from massive to layered and represent the amalgamation of the deposits from a large numbers of events. The volume of co-pyroclastic-flow fallout tephra is in the range 4-16° of the associated pyroclastic flow deposits. Dome-collapse fallout tephra is characterized by ash particles generated by fragmentation in the pyroclastic flows and by elutriation of fines. Vulcanian fallout tephra is coarser grained, as it is formed by magma fragmentation in the conduit and by elutriation from the fountain-collapse flows and initial surges. Vulcanian fallout tephra is typically polymodal, whereas dome-collapse fallout tephra is predominantly unimodal. Polymodality is attributed to: overlapping of fallout tephra of different types, premature fallout of fine particles, multiple tephra-fallout sources, and differences in density and grain-size distribution of different components. During both dome collapses and explosions, ash fell as aggregates of various sizes and types. Accretionary lapilli grain size is independent of their diameter and is characterized by multiple subpopulations with a main mode at 5o. Satellite data indicate that very fine ash can stay in a volcanic cloud for several hours and show that exponential thinning rates observed in proximal areas cannot apply in distal areas.

Eyewitness and survivor accounts allow reconstruction of the sequence of events on 25 June 1997, when a sustained partial collapse of the lava dome occurred leading to the death of 19 people. An unsteady pyroclastic flow was generated with three distinct pulses. The third flow pulse caused most of the damage to infrastructure and most, if not all, of the casualties. Pyroclastic surges detached along most of the path of the third flow pulse, and one travelled 70 m up an adjacent hillside. Observations were made that will be important for the development of mitigation measures at future events involving high-temperature flows and surges. Temperatures remained high (300-400°C) at the periphery of the most voluminous and extensive surge, even though dynamic pressure and velocity were low, causing the death of seven victims. Some people survived at the margins of the surge zone but suffered serious burns when they were forced to walk across the hot surge deposits to safety. Deflagration of buildings and vegetation was immediate within the pyroclastic surge and intense fires burned long after the volcanic activity had ceased. Fires could be a serious secondary hazard in an urban area. Search-and-rescue efforts were hampered in the immediate aftermath of the pyroclastic flows and surges by smoke and ash in the atmosphere. The hot, locally gas-rich surge deposits posed a major hazard to search-and-rescue workers and volcanologists for days afterwards. Despite the efforts of officials, scientists and concerned members of the public, about 80 people were in Zones A and B of the Exclusion Zone on 25 June 1997. Our findings suggest that many had become accustomed to the pyroclastic flows and had become overconfident in their own ability to judge the threat by observing repeated flows that had gradually increased runout but remained restricted to valleys. Many people had contingency plans and believed that there would be observable or audible warning signs from the volcano if the activity were to escalate significantly. However, there were no such discernible warnings and individual contingency plans proved inadequate. Public education should concentrate on correcting such public misapprehension of hazardous phenomena and attendant risks in future volcanic crises.

The Montserrat Volcano Observatory (MVO) is a statutory body of the Government of Montserrat and is the organization responsible for volcano monitoring operations on the island. It was formed shortly after the first phreatic explosions from Soufriere Hills Volcano occurred on 18 July 1995, and evolved from a hastily created, interim entity to a fully established volcano monitoring operation. Participating scientific teams have been drawn mainly from the Seismic Research Unit of the University of the West Indies, the US Geological Survey, the British Geological Survey and universities from various countries including the USA, UK, France and Puerto Rico. Despite its hurried inception, the MVO has been able to provide timely, high quality hazard advice to the civil authorities and has maintained an exceptional documentary record of all scientific aspects of the eruption. Its public education and information efforts have been extensive and there have been unusually high levels of interaction between scientists and the civil authorities, and between scientists and the public, both within Montserrat and outside in the wider world. The experience of setting up and running the MVO, under difficult and stressful conditions, has exemplified the advantages of teamwork and flexibility within monitoring operations and the benefits of openness and clarity in public interactions. Novel techniques have been applied to the appraisal of hazards and advances in scientific understanding have proved invaluable for risk assessment and management.

Dome growth at Soufriere Hills Volcano halted in early March 1998. After dome growth ceased, seismicity reduced significantly, but activity related to dome disintegration and degassing of magma at depth continued. A sustained episode of pyroclastic flows on 3 July 1998 marked the single largest collapse from March 1998 to November 1999. This led to a remarkable episode of dome collapses, low-energy explosions and ash-venting that resulted in the regular production of ash plumes, commonly reaching 1.5-6 km above sea level (a.s.l), but sometimes up to 11 km a.s.l., and the development of a small block-and-ash cone around the explosion crater. During the period of this residual activity, higher levels of activity occurred approximately every five to six weeks. This periodicity was similar to the cycles observed during active dome growth during 1995 to 1998, and probably had a similar cause. The relatively high level of observed activity caused continued concern regarding volcanic hazards and their potential to impact upon the resident population. Vigorous magma extrusion resumed in November 1999. The activity of the intervening period is attributed to the continued cooling and degassing of the dome, conduit and deep magma body, the impact of rising volcanic gases in the volcanic edifice, and limited magma flow in the conduit.

Since 2000, a network of volunteers known as vigías has been engaged in community-based volcano monitoring, which involves local citizens in the collection of scientific data, around volcán Tungurahua, Ecuador. This paper provides the first detailed description and analysis of this well-established initiative, drawing implications for volcanic risk reduction elsewhere. Based on 32 semi-structured interviews and other qualitative data collected in June and July 2013 with institutional actors and with vigías themselves, the paper documents the origins and development of the network, identifies factors that have sustained it, and analyses the ways in which it contributes to disaster risk reduction. Importantly, the case highlights how this community-based network performs multiple functions in reducing volcanic risk. The vigías network functions simultaneously as a source of observational data for scientists; as a communication channel for increasing community awareness, understanding of hazard processes and for enhancing preparedness; and as an early warning system for civil protection. Less tangible benefits with nonetheless material consequences include enhanced social capital – through the relationships and capabilities that are fostered – and improved trust between partners. Establishing trust-based relationships between citizens, the vigías, scientists and civil protection authorities is one important factor in the effectiveness and resilience of the network. Other factors discussed in the paper that have contributed to the longevity of the network include the motivations of the vigías, a clear and regular communication protocol, persistent volcanic activity, the efforts of key individuals, and examples of successful risk reduction attributable to the activities of the network. Lessons that can be learned about the potential of community-based monitoring for disaster risk reduction in other contexts are identified, including what the case tells us about the conditions that can affect the effectiveness of such initiatives and their resilience to changing circumstances.

A novel application of X-ray micro-computed tomography is described, which can be used to rapidly characterize chemical populations of natural olivine crystals in erupted basalts. This technique can be deployed during volcanic crises to directly track changes in magma components of an erupting system in near-real-time. Such changes are fundamental in controlling eruption style, duration and intensity. We demonstrate a method that can generate data from hundreds of crystals within hours, which allows time-series petrological data to be recorded and interpreted alongside various complementary monitoring techniques (e.g. seismicity, ground deformation). Our direct-detection will allow greater understanding of the dynamics of sub-volcanic magma plumbing systems, and can provide important insights into how an eruption may evolve. The same technique can also be used to generate rich baseline datasets from eruption sequences in the geological record in a more efficient manner than conventional methods allow.

The Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database contains data on 1,883 Quaternary eruption records of magnitude (M) 4 and above and is publically accessible online via the British Geological Survey. Spatial and temporal analysis of the data indicates that the record is incomplete and is thus biased. The recorded distribution of volcanoes is variable on a global scale, with three-quarters of all volcanoes with M≥4 Quaternary activity located in the northern hemisphere and a quarter within Japan alone. The distribution of recorded eruptions does not strictly follow the spatial distribution of volcanoes and has distinct intra-regional variability, with about 40% of all recorded eruptions having occurred in Japan, reflecting in part the country’s efforts devoted to comprehensive volcanic studies. The number of eruptions in LaMEVE decreases with increasing age, exemplified by the recording of 50% of all known Quaternary eruptions during the last 20,000 years. Historical dating is prevalent from 1450 AD to the present day, substantially improving record completeness. The completeness of the record also improves as magnitude increases. This is demonstrated by the calculation of the median time, T50, for eruptions within given magnitude intervals, where 50% of eruptions are older than T50: T50 ranges from 5,070 years for M4-4.9 eruptions to 935,000 years for M≥8 eruptions. T50 follows a power law fit, suggesting a quantifiable relationship between eruption size and preservation potential of eruptive products. Several geographic regions have T50 ages of

The uncertainty brought about by intermittent volcanic activity is fairly common at volcanoes worldwide. While better knowledge of any one volcano's behavioural characteristics has the potential to reduce this uncertainty, the subsequent reduction of risk from volcanic threats is only realised if that knowledge is pertinent to stakeholders and effectively communicated to inform good decision making. Success requires integration of methods, skills and expertise across disciplinary boundaries. This research project develops and trials a novel interdisciplinary approach to volcanic risk reduction on the remote volcanic island of Tristan da Cunha (South Atlantic). For the first time, volcanological techniques, probabilistic decision support and social scientific methods were integrated in a single study. New data were produced that (1) established no spatio-temporal pattern to recent volcanic activity; (2) quantified the high degree of scientific uncertainty around future eruptive scenarios; (3) analysed the physical vulnerability of the community as a consequence of their geographical isolation and exposure to volcanic hazards; (4) evaluated social and cultural influences on vulnerability and resilience; and (5) evaluated the effectiveness of a scenario planning approach, both as a method for integrating the different strands of the research and as a way of enabling on-island decision makers to take ownership of risk identification and management, and capacity building within their community. The paper provides empirical evidence of the value of an innovative interdisciplinary framework for reducing volcanic risk. It also provides evidence for the strength that comes from integrating social and physical sciences with the development of effective, tailored engagement and communication strategies in volcanic risk reduction.

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.

Mapping the transport and deposition of tephra is important for the assessment of an eruption’s impact on health, transport, vegetation and infrastructure, but it is challenging at large distances from a volcano (> 1000 km), where it may not be visible to the naked eye. Here we describe a range of methods used to quantify tephra deposition and impact on air quality during the 21–28 May 2011 explosive basaltic eruption of Grímsvötn volcano, Iceland. Tephra was detected in the UK with tape-on-paper samples, rainwater samples, rainwater chemistry analysis, pollen slides and air quality measurements. Combined results show that deposition was mainly in Scotland, on 23–25 May. Deposition was patchy, with adjacent locations recording different results. Tape-on-paper samples, collected by volunteer citizen scientists, and giving excellent coverage across the UK, showed deposition at latitudes >55°N, mainly on 24 May. Rainwater samples contained ash grains mostly 20–30 μ m long (maximum recorded grainsize 80 μ m) with loadings of up to 116 g r a i n s c m-2. Analysis of rainwater chemistry showed high concentrations of dissolved Fe and Al in samples from N Scotland on 24–27 May. Pollen slides recorded small glass shards (3–4 μ m long) deposited during rainfall on 24–25 May and again on 27 May. Air quality monitoring detected increased particulate matter concentrations in many parts of the country. An hourly concentration of particles 53°N) on 24 May but no negative effects on health were reported. Although the eruption column reached altitudes of 20 km above sea level, air mass trajectories suggest that only tephra from the lowest 4 km above sea level of the eruption plume was transported to the UK. This demonstrates that even low plumes could deliver tephra to the UK and suggests that the relative lack of basaltic tephra in the tephrochronological record is not due to transport processes.

To facilitate the assessment of hazards and risk from volcanoes, we have created a comprehensive global database of Quaternary Large Magnitude Explosive Volcanic Eruptions (LaMEVE). This forms part of the larger Volcanic Global Risk Identification and Analysis Project (VOGRIPA), and also forms part of the Global Volcano Model (GVM) initiative (http://www.globalvolcanomodel.org). A flexible search tool allows users to select data on a global, regional or local scale; the selected data can be downloaded into a spreadsheet. The database is publically available online at http://www.bgs.ac.uk/vogripa and currently contains information on nearly 3,000 volcanoes and over 1,800 Quaternary eruption records. Not all volcanoes currently have eruptions associated with them but have been included to allow for easy expansion of the database as more data are found. Data fields include: magnitude, Volcanic Explosivity Index (VEI), deposit volumes, eruption dates, and rock type. The scientific community is invited to contribute new data and also alert the database manager to potentially incorrect data. Whilst the database currently focuses only on large magnitude eruptions, it will be expanded to include data specifically relating to the principal volcanic hazards (e.g. pyroclastic flows, tephra fall, lahars, debris avalanches, ballistics), as well as vulnerability (e.g. population figures, building type) to facilitate risk assessments of future eruptions.

The 2010 Eyjafjallajokull lasted 39 days and had 4 different phases, of which the first and third (14-18 April and 5-6 May) were most intense. Most of this period was dominated by winds with a northerly component that carried tephra toward Europe, where it was deposited in a number of locations and was sampled by rain gauges or buckets, surface swabs, sticky-tape samples and air filtering. In the UK, tephra was collected from each of the Phases 1-3 with a combined range of latitudes spanning the length of the country. The modal grain size of tephra in the rain gauge samples was 25 mu m, but the largest grains were 100 mu m in diameter and highly vesicular. The mass loading was equivalent to 8-218 shards cm(-2), which is comparable to tephra layers from much larger past eruptions. Falling tephra was collected on sticky tape in the English Midlands on 19, 20 and 21st April (Phase 2), and was dominated by aggregate clasts (mean diameter 85 mu m, component grains

[1] During the 2010 eruption of Eyjafjallajokull, improvements were made to the modeling procedure at the Met Office, UK, enabling peak ash concentrations within the volcanic cloud to be estimated. In this paper we describe the ash concentration forecasting method, its rationale and how it evolved over time in response to new information and user requirements. The change from solely forecasting regions of ash to also estimating peak ash concentrations required consideration of volcanic ash emission rates, the fraction of ash surviving near-source fall-out, and the relationship between predicted mean and local peak ash concentrations unresolved by the model. To validate the modeling procedure, predicted peak ash concentrations are compared against observations obtained by ground-based and research aircraft instrumentation. This comparison between modeled and observed peak concentrations highlights the many sources of error and the uncertainties involved. Despite the challenges of predicting ash concentrations, the ash forecasting method employed here is found to give useful guidance on likely ash concentrations. Predicted peak ash concentrations lie within about one and a half orders of magnitude of the observed peak concentrations. A significant improvement in the agreement between modeled and observed values is seen if a buffer zone, accounting for positional errors in the predicted ash cloud, is used. Sensitivity of the predicted ash concentrations to the source properties (e.g., the plume height and the vertical distribution of ash at the source) is assessed and in some cases, seemingly minor uncertainties in the source specification have a large effect on predicted ash concentrations.

As a result of the serious consequences of the 2010 Eyjafjallajökull eruption (Iceland) on civil aviation, 52 volcanologists, meteorologists, atmospheric dispersion modellers, and space and ground-based monitoring specialists from 12 different countries (including representatives from 6 Volcanic Ash Advisory Centres and related institutions) gathered to discuss the needs of the ash-dispersal modelling community, investigate new data-acquisition strategies (i.e., quantitative measurements and observations), and discuss how to improve communication between the research community and institutions with an operational mandate. Based on a dedicated benchmark exercise and on three days of in-depth discussion, recommendations have been made for future model improvements, new strategies of ash cloud forecasting, multidisciplinary data acquisition, and more efficient communication between different communities. Issues addressed in the workshop include ash dispersal modelling, uncertainty, ensemble forecasting, combining dispersal models and observations, sensitivity analysis, model variability, data acquisition, pre-eruption forecasting, first simulation and data assimilation, research priorities, and new communication strategies to improve information flow and operational routines. As a main conclusion, model developers, meteorologists, volcanologists and stakeholders need to work closely together to develop new and improved strategies for ash dispersal forecasting and, in particular, to: i) improve the definition of the source term, ii) design models and forecasting strategies that can better characterize uncertainties, iii) explore and identify the best ensemble strategies that can be adapted to ash dispersal forecasting, iv) identify optimized strategies for the combination of models and observations and v) implement new critical operational strategies.

[1] The third episode of lava dome growth at Soufriere Hills Volcano, Montserrat was characterised by higher average magma discharge rates than either previous dome growth episode at this volcano and yet fewer collapses. During sustained dome growth at moderate-high average rates (>6 m3/s), we identified 2–6 week discharge pulses that each supplied c.20 Mm3 magma from depth. Our observations are consistent with some existing models but we explain discrepancies by a combination of higher volatile contents and higher ascent rates. Cycles of c. 11–16 days were evident in rockfall, LP rockfall and shallow LP earthquake counts related to dome growth and degassing. We speculate that degassing at the conduit margins together with stick-slip conduit flow may drive these cycles. Only one major collapse >10 Mm3 occurred during the third episode (on May 20, 2006) as a new magma pulse entered the dome and coincided with heavy rainfall.

[1] Noritic anorthosite, gabbroic anorthosite and hornblende-gabbro xenoliths are ubiquitous in the host andesite at Montserrat. Other xenoliths include quartz diorite, metamorphosed biotite-gabbro, plagioclase-hornblendite and plagioclase-clinopyroxenite. Mineral compositions suggest a majority of the xenoliths are cognate. Cumulate, hypabyssal and crescumulate textures are present. A majority of the xenoliths are estimated to have seismic velocities of 6.7–7.0 km/s for pore-free assemblages. These estimates are used in conjunction with petrological models to constrain the SEA CALIPSO seismic data and the structure of the crust beneath Montserrat. Andesitic upper crust is interpreted to overlie a lower crust dominated by amphibole and plagioclase. Xenolith textures and seismic data indicate the presence of hypabyssal intrusions in the shallow crust. The structure of the crust is consistent with petrological models indicating that fractionation is the dominant process producing andesite at Montserrat.

The third episode of lava dome growth at Soufriere Hills Volcano began 1 August 2005 and ended 20 April 2007. Volumes of the dome and talus produced were measured using a photo-based method with a calibrated camera for increased accuracy. The total dense rock equivalent (DRE) volume of extruded andesite magma (306 ± 51 Mm3) was similar within error to that produced in the earlier episodes but the average extrusion rate was 5.6 ± 0.9 m3s−1 (DRE), higher than the previous episodes. Extrusion rates varied in a pulsatory manner from

range and intensity measurements of the change in summit lava (� 1.5 � 10 6 m 3 , 22%), (2) AVTIS range measurements to measure the talus growth (� 3.9 � 10 6 m 3 , 57%), and (3) rockfall seismicity to measure the pyroclastic flow deposit volumes (� 1.4 � 10 6 m 3 , 21%), which gives an overall dense rock equivalent extrusion rate of about 7 m 3 � s � 1 . These figures demonstrate how efficient nonexplosive lava dome growth can be in generating large volumes of primary clastic deposits, a process that, by reducing the proportion of erupted lava stored in the summit region, will reduce the likelihood of large hazardous pyroclastic flows.