A thermodynamical model for rainfall-triggered volcanic dome collapse

Dome-forming volcanic eruptions typically involve the slow extrusion of viscous lava onto a steep-sided volcano punctuated by collapse and the generation of hazardous pyroclastic flows. We show an unequivocal link between the onset of intense rainfall and lava dome collapse on short time scales (within a few hours) and develop a simple thermodynamical model to explain this behavior. The model is forced with rainfall observations from the Soufriere Hills Volcano, Montserrat, and suggests that when the dome is in a critical state, a minimum rainfall rate of approximately 15 mm hr-1 for 2-3 hr could trigger a dome collapse

Remembering, forgetting, and absencing disasters in the post-disaster recovery process

Sustainable post-disaster recovery implies learning from past experience in order to prevent recreating forms of vulnerability. Memory construction supports both the healing process and redevelopment plans. Hence, memory of disaster results from the balance between remembering, forgetting, and absencing elements of the disaster, and can be both a tool and an obstacle to sustainable recovery. We explore here how collective memory is built in a post-disaster context to respond to the needs of this critical period, and how it shapes recovery. This ethnographic study, conducted between 2015 and 2017, explores the recovery processes in Montserrat, a small Caribbean island affected by an extended volcanic crisis from 1995 to 2010. Although this study does not give tangible solutions for disaster risk reduction in a post-disaster context, it highlights potential obstacles for learning from a disaster and how they may be surmounted. We argue that it is crucial to acknowledge evolving collective memory in order to implement effective measures for preserving and sharing a shared understanding of disaster across generations and social groups in a way that supports disaster risk awareness. We also maintain that acknowledging the dilemma faced by authorities and disaster management agencies during a period of conflicting needs may encourage the reconsideration of risk framing, and hence reveal how to improve implementation of disaster risk reduction measures

Scientists as storytellers: the explanatory power of stories told about environmental crises

This paper examines how storytelling functions to share and to shape knowledge, particularly when scientific knowledge is uncertain because of rapid environmental change. Narratives or stories are the descriptive sequencing of events to make a point. In comparison with scientific deduction, the point (plot) of a story can be either implicit or explicit, and causal links between events in the story are interpretative, rendering narrative a looser inferential framework. We explore how storytelling (the process) and stories (or narratives) involving scientists can make sense of environmental crises, where conditions change rapidly and natural, social, and scientific systems collide. We use the example of the Soufrière Hills volcanic eruption (Montserrat) and scientists' experiences of the events during that time. We used 37 stories gathered from seven semi-structured interviews and one group interview (five scientists). We wanted to understand whether these stories generate or highlight knowledge and information that do not necessarily appear in more conventional scientific literature produced in relation to environmental crisis and how that knowledge explicitly or implicitly shapes future actions and views. Through our analysis of the value these stories bring to volcanic risk reduction, we argue that scientists create and transmit important knowledge about risk reduction through the stories they tell one another. In our example storytelling and stories are used in several ways: (1) evidencing the value of robust long-term monitoring strategies during crises, (2) exploring the current limits of scientific rationality and the role of instinct in a crisis, and (3) the examination of the interactions and outcomes of wide-ranging drivers of population risk. More broadly these stories allowed for the emotional intensity of these experiences to be acknowledged and discussed; the actions and outcomes of the storytelling are important. This is not about the “story” of research findings but the sharing of experience and important knowledge about how to manage and cope with volcanic crises. We suggest that storytelling frameworks could be better harnessed in both volcanic and other contexts

The 1902–3 eruptions of the Soufrière, St Vincent: Impacts, relief and response

Retrospective analysis of the contemporary colonial and scientific records of a major explosive eruption of the Soufrière of St Vincent from 1902 to 1903 reveals how this significant and prolonged event presented challenges to the authorities charged with managing the crisis and its aftermath. In a small-island setting vulnerable to multiple hazards, the spatial footprint of the volcanic hazard and the nature and intensity of the hazard effects were rather different to those of other recurrent hazards such as hurricanes. The eruption affected the same parts of the island that had been impacted by prior explosive eruptions in 1718 and 1812, and hurricanes in 1831 and 1898, with consequences that disproportionately affected those working in and around the large sugar estates. The official response to the eruption, both in terms of short-term relief and remediation, was significantly accelerated by the existence of mature plans for land-reform following the collapse of the sugar market, and ongoing plans for rebuilding in the aftermath of the destructive hurricane of 1898. The picture that this analysis helps to illuminate provides insights both into the nature of the particular eruptive episode, and the human and social response to that episode. This not only informs discussion and planning for future explosive eruptions on St Vincent, but provides important empirical evidence for building effective responses in similar multihazard context

Interpreting flash flood palaeoflow parameters from antidunes and gravel lenses: An example from Montserrat, West Indies

The wavelength of stationary water–surface waves and their associated antidune bedforms are related to the mean velocity and depth of formative flow. In sand-bed flume experiments, Alexander et al. (2001) found that lens structures were preserved during antidune growth and change, and the dimension of the lenses were empirically related to antidune wavelength, and thus could be used to estimate flow velocity and depth. This study is the first to compare observations of formative flow conditions and resulting sedimentary structures in a natural setting, testing the Alexander et al. (2001) relationship at a field-scale. Trains of stationary and upstream migrating water–surface waves were prevalent during the flash flood in October 2012 in the Belham Valley, Montserrat, West Indies. Wave positions and wavelengths were assessed at 900 s intervals through the daylight hours of the event within a monitored reach. The wave data indicate flow depths up to 1.3 m and velocity up to 3.6 m s−1. Sedimentary structures formed by antidune growth and change were preserved in the event deposit. These structures include lenses of clast-supported gravel and massive sand, with varying internal architecture. The lenses and associated low angle strata are comparable to sand-bed structures formed from stationary and upstream migrating waves in flume experiments, confirming the diagnostic value of these structures. Using mean lens length in the event deposit underestimated peak flow conditions during the flood, and implied that the lenses were preserved during waning flow

Caught in the act: Implications for the increasing abundance of mafic enclaves during the eruption of the Soufriere Hills Volcano, Montserrat

An exceptional opportunity to sample several large blocks sourced from the same region of the growing Soufrière Hills lava dome has documented a significant increase in the presence of mafic enclaves in the host andesite during the course of a long-lived eruptive episode with several phases. In 1997 (Phase I) mafic inclusions comprised ~1 volume percent of erupted material; in 2007 (Phase III) deposits their volumetric abundance increased to 5–7 percent. A broader range of geochemically distinctive types occurs amongst the 2007 enclaves. Crystal-poor enclaves generally have the least evolved (basaltic) compositions; porphyritic enclaves represent compositions intermediate between basaltic and andesitic compositions. The absence of porphyritic enclaves prior to Phase III magmatism at Soufrière Hills Volcano suggests that a mixing event occurred during the course of the current eruptive episode, providing direct evidence consistent with geophysical observations that the system is continuously re-invigorated from depth

Order effects in high stakes undergraduate examinations: an analysis of 5 years of administrative data in one UK medical school.

OBJECTIVE: To investigate the association between student performance in undergraduate objective structured clinical examinations (OSCEs) and the examination schedule to which they were assigned to undertake these examinations. DESIGN: Analysis of routinely collected data. SETTING: One UK medical school. PARTICIPANTS: 2331 OSCEs of 3 different types (obstetrics OSCE, paediatrics OSCE and simulated clinical encounter examination OSCE) between 2009 and 2013. Students were not quarantined between examinations. OUTCOMES: (1) Pass rates by day examination started, (2) pass rates by day station undertaken and (3) mean scores by day examination started. RESULTS: We found no evidence that pass rates differed according to the day on which the examination was started by a candidate in any of the examinations considered (p>0.1 for all). There was evidence (p=0.013) that students were more likely to pass individual stations on the second day of the paediatrics OSCE (OR 1.27, 95% CI 1.05 to 1.54). In the cases of the simulated clinical encounter examination and the obstetrics and gynaecology OSCEs, there was no (p=0.42) or very weak evidence (p=0.099), respectively, of any such variation in the probability of passing individual stations according to the day they were attempted. There was no evidence that mean scores varied by day apart from the paediatric OSCE, where slightly higher scores were achieved on the second day of the examination. CONCLUSIONS: There is little evidence that different examination schedules have a consistent effect on pass rates or mean scores: students starting the examinations later were not consistently more or less likely to pass or score more highly than those starting earlier. The practice of quarantining students to prevent communication with (and subsequent unfair advantage for) subsequent examination cohorts is unlikely to be required.University of Cambridge School of Clinical MedicineThis is the final version of the article. It first appeared from BMJ Group via http://dx.doi.org/10.1136/bmjopen-2016-01254

Transitions:comparing timescales of eruption and evacuation at Volcán de Fuego (Guatemala) to understand relationships between hazard evolution and responsive action

During volcanic crisis, effective risk mitigation requires that institutions and local people respond promptly to protect lives and livelihoods. In this paper, we ask: over what timescales do explosive paroxysmal eruptions evolve? And how do these timescales relate to those of people’s past responses? We explore these questions by comparing timescales of eruptions and evacuations for several recent events at Volcán de Fuego (Guatemala) to identify lags in evacuation and determine the drivers of these lags. We use multiple geophysical datasets for explosive paroxysmal eruptions (“paroxysms”) in 2012–2018 to constrain timescales of eruptive evolution. In parallel, we determine timescales of response and the impacts of uncertainty and eruptive behaviours on decision-making through interviews with institutional and local actors. We then compare eruption and response timescales to explore the drivers for decision-making, whether volcanic, institutional, or personal. We find that eruption and response timescales are comparable. However, we also find that periods of decision-making and warning dissemination delay response until well after eruptive onset. We document how in recent eruptions, response occurs during eruptive climax when risk is at peak. We use paired timelines to elucidate the key drivers of this ‘response lag’ and show that despite the high levels of forecasting uncertainty, response times could be improved by agreed means to collaborate through shared information and agreed actions. We conclude by considering how the analysis presented here might be useful to different actors who share the goal of preserving lives and livelihoods at Fuego, focussing on how community’s needs can be met such that during an eruptive crisis the community can evacuate in time. Our analysis offers practical insights for people working to mitigate risk to populations near active volcanoes around the world.</p

Global Mapping of Citizen Science Projects for Disaster Risk Reduction

Citizen science for disaster risk reduction (DRR) holds huge promise and has demonstrated success in advancing scientific knowledge, providing early warning of hazards, and contributed to the assessment and management of impacts. While many existing studies focus on the performance of specific citizen science examples, this paper goes beyond this approach to present a systematic global mapping of citizen science used for DRR in order to draw out broader insights across diverse methods, initiatives, hazards and country contexts. The systematic mapping analyzed a total of 106 cases of citizen science applied to DRR across all continents. Unlike many existing reviews of citizen science initiatives, relevance to the disaster risk context led us to ‘open up’ our mapping to a broader definition of what might constitute citizen science, including participatory research and narrative-based approaches. By taking a wider view of citizen science and opening up to other disciplinary practices as valid ways of knowing risks and hazards, we also capture these alternative examples and discuss their relevance for aiding effective decision-making around risk reduction. Based on this analysis we draw out lessons for future research and practice of citizen science for DRR including the need to: build interconnections between disparate citizen science methods and practitioners; address multi-dimensionality within and across hazard cycles; and develop principles and frameworks for evaluating citizen science initiatives that not only ensure scientific competence but also attend to questions of equity, responsibility and the empowerment of those most vulnerable to disaster risk

The fast response of volcano-seismic activity to intense precipitation: Triggering of primary volcanic activity by rainfall at Soufrière Hills Volcano, Montserrat

One-minute resolution time series of rainfall and seismic data from the Soufriere Hills Volcano, Montserrat are analysed to explore the mechanism of external forcing of volcanic eruptions by rainfall over three years of activity. The real-time seismic amplitude (RSAM) shows a narrow, statistically significant, peak within 30 min after the start of intense rainfall events, and a much broader peak with a lag of 6?40 h. The classified seismic events indicate that the volcanic response to rainfall begins at the surface and gradually penetrates deeper into the dome, as there is an increase in the pseudo-magnitude of: surface rockfall events (including pyroclastic flows) with lags from the first 30 min to 40 h, long-period rockfalls (from shallow degassing) at lags of 4 and 14 h, and long-period and hybrid events (source depth approximately 1 km) with lags at 14 and 24 h after the start of rainfall events. There was no rainfall-related change in deeper, volcano-tectonic activity. There was no change in the frequency of any type of classified event, indicating that the rainfall acts to modulate existing, internal processes, rather than generating new events itself. These robust results are due to many (229) different rainfall events, and not just to a few, large magnitude cases. The rainfalltriggered volcanic activity examined here is consistent with a model of fast, shallow interactions with rainfall at the dome surface, after which, a deeper dome collapse follows