The first seismo-volcanological observatory in the anglophone Caribbean was established on Montserrat in 1936, in response to a volcano-seismic crisis that began with repeated felt events in 1933. Staff at Montserrat's agricultural office began routinely recording earthquake shocks in 1934. In 1936, following a scientific expedition dispatched by the Royal Society, an observatory was established at the Grove Botanical Station, Plymouth. This was run by volcano-seismic observers who managed an instrumental network, and monitored gas and steam emissions and air quality. The observatory functioned until 1946. We reconstruct the decision-making and evolution of the instrument networks as the observatory was established, and highlight the personnel involved, including the first female seismo-volcanic observer on Montserrat, Greta Scotland. Observations from the 1930s crisis emphasise the persistent seismicity and gas emissions associated with this extended episode of unrest, and suggest that there were minor phreatic explosions at the height of the crisis. We draw parallels with long-term observations of the activity of the Soufrière Hills Volcano since the 1990s.

In the 1930s Montserrat, part of the British Leeward Islands colony, experienced a prolonged period of seismic unrest which many on the island interpreted as presaging a volcanic eruption. During the crisis several international scientists visited Montserrat and advised the local and imperial authorities on the likelihood of an eruption, and the island became a key node in an increasingly global volcanology. The process of assembling reliable knowledge about the volcanic system and its likely future behaviour was nonetheless heavily structured by colonial hierarchies and contestations over the reliability of different observers and the utility of long term monitoring. When the volcano eventually began erupting in 1995 it put paid to lingering governmental doubts over its very existence. We propose that work on the geographies of science has so far paid insufficient attention to the spatialities of crisis science, and that doing so can shed new light on both the history and persistence of colonial practices in the environmental sciences and in disaster management. Adopting longer perspectives on the politics of crisis science can yield new insights into the geographies and political geologies of a crisis-ridden present. (c) 2025 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Volcano deformation models contribute to hazard assessment by simulating magma system dynamics. Traditional magma reservoir pressure source shape assumptions often fail to replicate irregular, geophysically identified geometries. Uncertainties regarding the influence of reservoir geometry can limit the effectiveness of using deformation models to decipher unrest signals. Here, we aim to determine the feasibility of using a magma reservoir geometry directly derived from a seismic tomography survey in a volcano deformation model for Soufri & egrave;re Hills Volcano, Montserrat. Three-dimensional deformation models are created to simulate displacement using a pressure source geometry constrained from a low seismic velocity anomaly, inferred to be a region of partial melt, and contrasted against a traditional ellipsoid reservoir geometry. We also test a "hybrid" model combining a seismically inferred reservoir upper geometry and ellipsoidal base. Results of each model are evaluated against ground displacement observed on Montserrat from 2010 to 2022. Our results show that different reservoir geometries change the horizontal and vertical displacement fields across the island: the ellipsoid reservoir best reproduces vertical displacement magnitude, while the hybrid reservoirs best simulate horizontal displacement vectors and the region of maximum uplift. Overall, the ellipsoid-shaped reservoir provides our best-fit to the observed data, but we note this result could be biased due to prior years of optimization helping constrain the ellipsoid shape, size, and location. Our results show the potential for further use of geophysically constrained reservoir geometries in deformation modeling, and our methods could be applied to other deforming volcanoes worldwide.

Volcano deformation studies traditionally consider melt-dominated magma reservoirs, often overlooking the significant role of poroelastic mush in modifying surface deformation. Here, we analyze the deformation of Soufrière Hills Volcano (SHV) with a focus on a mush-dominated, poroelastic magma reservoir, drawing on temporal deformation data from 14 continuous GPS stations during the ongoing intra-eruptive unrest period. We implemented a 3D Finite Element model and optimization to simulate the observed deformation. Our results reveal that the deformation is likely driven by ongoing, melt injection (Q = 1.1 m³ sec⁻¹) into a low permeability (k = 4.7 × 10⁻¹⁰ m²) reservoir with the injection to the base of the reservoir at 16.5 km depth below sea level. Our findings highlight temporal variations in the melt injection rate to fit the decreasing GPS-recorded deformation rates. An initial injection rate Qi = 1.9 m³ sec⁻¹ inferred at the start of our study period decreases to Qf = 0.3 m³ sec⁻¹ over a 12-year period (2010–2022). Exploratory forward modeling suggests that if current trends continue, the end of magma supply to our modelled reservoir could occur around June 2024 ± 2 years. However, this does not imply the end of associated volcanic hazards at SHV, as the poroelastic diffusion of melt will continue, causing redistribution of melt, surface deformation, and potentially initiating reservoir rupture. While our models offer new insights, inherent limitations in our simulations include interdependencies among our explored model parameters that would benefit from further refinement. Despite these limitations, the study offers crucial guidance on understanding and forecasting volcano deformation dynamics, particularly for volcanoes like SHV with crystal-rich magma reservoirs.

Measurements of surface deformation provide valuable insight into sub-volcanic processes operating before, during and after eruptions. Here, we investigate the drivers behind the 2020-21 effusive-explosive episode at La Soufriere volcano in St Vincent using Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data between 2018 and 2021, and geodetic modelling. We observe inflation up to six months before the start to the effusive phase, which continued as the dome extruded. Once the eruption transitioned to the explosive phase, the volcano rapidly deflated, the bulk happening within the first three days of explosions. Our analytical modelling distinguishes three pressure source depth ranges contributing to this eruptive episode: 16-20, c. 6 and,1 km. Deformation data are therefore in line with a vertically extensive magmatic system being tapped pre- and syn-eruption with interaction between deep and shallow reservoirs by ascending magma batches. The combined use of GPS and InSAR proved to be instrumental for constraining the deformation field active during this eruptive episode. The direction of future geodetic monitoring at La Soufriere should therefore utilize both techniques with a view towards maximizing coverage while making up for shortfalls in station upkeep and variations in satellite overpass regularity.

Abstract Volcano GPS networks can capture vital information during volcanic unrest to aid with hazard assessment and eruption forecasting, but can be hindered by their discrete point locations and possibly miss key spatial information. We show how numerical models can reveal controls on spatial deformation signal intensity compared against GPS network design. Using the GPS network at Soufrière Hills Volcano (SHV), Montserrat, and a range of models, we explore expected surface deformation patterns. Peak horizontal deformation is located offshore, highlighting the difficulties with geodetic monitoring on small ocean‐island volcanoes. Onshore areas where the deformation signal is expected to be high are also identified. At SHV, topography plays a greater role in altering the relative distribution of surface displacement patterns than subsurface heterogeneity. Our method, which can be adapted for other volcanoes, highlights spatial areas that can be targeted for effective GPS station placement to help improve deformation monitoring efficiency.

Volcano deformation studies often neglect the role of the porous, crystal-rich magma reservoirs in modulating surface deformation patterns. Our study examines the current deformation at Soufrière Hills Volcano (SHV) in its ongoing intra-eruptive unrest, with an emphasis on the influence of a mush-dominated, poroelastic magma reservoir. Using 3D finite element models constrained by 14 continuous GPS stations, our findings indicate deformation caused by ongoing melt injection into a low permeability (4.7 x 10-10 m2) reservoir with the injection source located at 16.5 km depth below sea level. Our models show that the melt supply likely decreased linearly from ~1.9 to ~0.3 m3/sec between 2010 and 2022, fitting the recorded decreasing GPS displacement rates. Projective modelling indicates a potential full cessation in melt injection around mid-2024 ± 2 years, but poroelastic melt diffusion will continue, deforming the surface and potentially impacting the stability of the reservoir. Future expansions of this study will incorporate dynamic magma property changes from existing thermodynamic models to represent pressure, temperature and volatile-dependent magma evolution. Our study sheds light on the understanding of deformation patterns at volcanoes, particularly those with crystal-abundant magma reservoirs like SHV.

We modelled ground deformation at Soufrière Hills Volcano (SHV), using data collected by the Montserrat Volcano Observatory from 2010–2019. We investigate the combined use of Electronic Distance Measuring (EDM) and Global Positioning System (GPS) to distinguish shallow from mid-crustal magmatic processes and their surface deformation profiles. Our results suggest that the EDM network responds predominantly to changes in the shallow magmatic system, whereas GPS records variation at mid-crustal levels. In addition, we show that the behaviour of the EDM network, and of the GPS site HERM, can be explained by underpressurisation in a shallow dyke conduit orientated NNW–SSE, while the mid-crustal system was still undergoing pressurisation. The modelled dyke may be responding to magma cooling and contraction associated with a previous intrusion. We find that geodetic monitoring coverage of multiple flanks within 1 km of the vent can improve our understanding of shallow magmatic system processes with asymmetric deformation fields.

A critical challenge during volcanic emergencies is responding to rapid changes in eruptive behaviour. Actionable advice, essential in times of rising uncertainty, demands the rapid synthesis and communication of multiple datasets with prognoses. The 2020–2021 eruption of La Soufrière volcano exemplifies these challenges: a series of explosions from 9–22 April 2021 was preceded by three months of effusive activity, which commenced with a remarkably low level of detected unrest. Here we show how the development of an evolving conceptual model, and the expression of uncertainties via both elicitation and scenarios associated with this model, were key to anticipating this transition. This not only required input from multiple monitoring datasets but contextualisation via state-of-the-art hazard assessments, and evidence-based knowledge of critical decision-making timescales and community needs. In addition, we share strategies employed as a consequence of constraints on recognising and responding to eruptive transitions in a resource-constrained setting, which may guide similarly challenged volcano observatories worldwide.

Dome-building volcanoes are particularly challenging for volcanic hazard assessment, where long-term eruptive episodes can be interspersed with periods of intra-eruptive repose. Defining the end of eruptive episodes is vitally important for the socio-economic recovery of affected communities, but highly problematic due to the potential for prolonged, seemingly low-risk, repose to rapidly transition to dangerous effusive or explosive activity. It is currently unclear what constitutes the end of repose and an eruptive episode. Here we show that analysis of surface deformation can characterise repose and help define an eruptive episode. At Soufrière Hills volcano (SHV) the observed long-term deformation requires the pressure in the magma system to increase with time; time-dependent stress relaxation or crustal creep cannot explain the deformation trends alone. Continued pressurisation within the magmatic system during repose could initiate a renewed eruption, qualifying as sustained unrest and therefore continuation of the eruptive episode. For SHV, persistent magma pressurisation highlights the need for sustained vigilance in the monitoring and management of the volcano and its surroundings, despite the last eruptive activity ending in 2010.

Soufrière Hills Volcano (SHV) is an andesitic dome-building volcano on the island of Montserrat (British West Indies). SHV began its current, and anomalously long, eruption in 1995, but eruptive activity has been intermittent with phases of lava extrusion separated by periods of relative quiescence. The current pause in eruption started in February 2010 and is the longest yet recorded, 10 years and 11 months at the time of writing (January 2021). Continuous GPS measurements show island-wide inflation from 2010 onwards, with the rate of inflation slowly decreasing with time. However, the length of the eruptive pause raises questions as to whether there have been significant changes to the magmatic system and/or the eruption at SHV might have ended. To assess the behaviour and evolution of the SHV magmatic system since 2010 and the relation to ongoing hazard assessment, we analyse the continuous GPS temporal deformation trends using a suite of geodetic numerical models. Our models incorporate a temperature-dependent viscoelastic rheology, topography derived from a Digital Elevation Model and three-dimensional variations in mechanical properties derived from seismic tomography. The models are driven using one of four possible time-dependent source functions, to simulate differences in the temporal evolution of the magmatic system. The results show that the observed deformation data requires a temporal source function whereby the magmatic system pressure is increasing with time. A viscoelastic crustal response cannot explain the long-term deformation trends alone. The nature of the source pressurisation is unclear, and could be due, for example, to one or a combination of, magma supply, degassing/volatile influx, or overturning within a transcrustal magmatic system. Continued pressurisation within the magmatic system highlights the need for sustained vigilance in the monitoring and management of the volcano and its surroundings.

Ground deformation offers vital insight into the activity of volcanoes, as well as the characteristics of the magmatic systems that feed them. The extended eruption of the Soufrière Hills Volcano (SHV) has allowed for the development of a comprehensive multi-disciplinary monitoring network, which has aided extensive research into the magmatic system underlying the volcano. The modern network comprises GPS, strainmeters, and cheaper Electronic Distance Measurement (EDM). However, the island’s EDM network has to date only being used for monitoring the SHV. Here, for the first time, we co-analyse the EDM dataset from 2010-19 with the GPS data from the same period. This study aims to delineate the modern magmatic system conditions by building 3D Finite Element Models, as well as assessing the best use of EDM data in modelling the SHV.The island-wide deformation recorded over the past decade at the GPS network is broadly radial relative to the SHV dome, with a decreasing deformation rate. The EDM data shows line lengthening on the west and east flanks of the volcano, but minor line length shortening on the northern flank. We utilise Finite Element Modelling to model the SHV magmatic system as a single elongated prolate with 3D topography incorporated. We systematically test a wide range of parameters to explore how both EDM and GPS record perturbations to the magmatic system. Our preliminary results show that variations of certain parameters to the deeper magmatic system have an impact on both EDM and GPS timeseries, while some parameters (e.g., source pressure, source depth, and source location) have a more significant effect on EDM measurements than others (e.g., source shape).

We all experience and understand volcanic eruptions differently; it is at the intersection of these experiences that the most valuable knowledge for effective future disaster risk reduction is generated. On one hand, scientific responses to eruptions have the potential to improve understanding of subsurface magma movement and anticipate volcanic impacts on communities and the environment. On the other, social and cultural responses have the potential to help communities learn, respond and adapt to eruptions. The aim of ‘Disaster Passed’ is to bring together and celebrate these different forms of knowledge. Here, we demonstrate key aspects of our interactive exhibits designed to convey the lived experience, scientific monitoring and cultural responses to past eruptions on St. Vincent and Montserrat. The centrepieces are two volcano-shaped mobile exhibits (‘Soufrière Blow’ and ‘MountainAglow’) covered with panels that display images and information about past eruptions, together with poetry, calypso lyrics and prose inspired by the impacts of these eruptions. We further embellished MountainAglow with two add-on audio-visual features, ‘FLOW’ and ‘NEST’. FLOW, a ~3m column, encrusted with ~2000 LEDs, has seven audio-visual modes which portray a variety of volcanic phenomena, such as the movement of magma within the volcano and the gentle incandescence of the lava dome, accompanied by songs and recordings of Montserratians sharing their experiences of different phases of the Soufrière Hills eruption. NEST consists of a series of ash-strewn communication devices (a telephone, a walkie talkie and a radio) which play on-demand memories of the eruption as both spoken word and calypso. Soufrière Blow was deployed to St Vincent in 2018 has since been exhibited in multiple sites; MountainAglow was previewed at the Norwich Science Festival before being permanently moved to Montserrat in 2019, where it has been exhibited at the Montserrat Community College, National Trust, and deployed temporarily at primary schools. Our research on volcanic disaster risk has demonstrated the power of lived experience as a mechanism for improved response in the future. Therefore, a second purpose of Disaster Passed was to entwine critical risk messages with lived experience, and in so doing further enrich everyone’s understanding. Our collaborative approach to exhibit design generated and uncovered material with value beyond the physical exhibits, and so a final aspect of Disaster Passed is the creation of a website that shares these histories, songs and scientific data that helped to respond to past eruptions (disasterspassed.com; mountainaglow.com). Throughout Disaster Passed, the design process has been dynamic, underpinned by collaboration between scientific bodies, governmental organisations and, critically, the wider community. Indeed, at the time of writing, in collaboration with the Montserrat Volcano Observatory, the primary schools of Montserrat are designing new panels and audio-visuals for MountainAglow to reflect their own learning about the volcano. In this presentation we reflect on the challenges and successes of this dynamic design and collaborative approach. Finally, we will share how it influenced our own disciplinary ideas and the outcomes of our evaluation of the process.

The three dimensional distribution of water vapour around mountainous terrain can be highly variable. This variability can in turn affect local meteorological processes and geodetic techniques to measure ground surface motion. We demonstrate this general problem with the specific issues of a small tropical island, Montserrat. Over a period of 17 days in December 2014 we made observations using InSAR and GPS techniques, together with concurrent atmospheric models using the WRF code. Comparative studies of water vapour distribution and its effect on refractivity were made at high spatial resolution (300 m) over short distances (similar to 10 km). Our results show that model simulations of the observed differences in water vapour distribution using WRF is insufficiently accurate. We suggest that better use could be made of the knowledge and observations of local water vapour conditions at different scales, specifically the Inter Tropical Convergence Zone (ITCZ), the trade wind fields and the mountain flow (similar to 30 m) perhaps using eddy simulation. The annual perturbations of the ITCZ show that the range of humidity is approximately the same expressed as the differential phase of InSAR imaging (similar to 100 mm). Trade wind direction and speed are particularly important at high wind speeds driving vigorous asymmetrical convection over the island's mountains. We also show that the slant angles of radar can follow distinct separate paths through the water vapour field. Our study is novel in demonstrating how synoptic-scale features and climate can advise the modelling of mesoscale systems and sub-seasonal InSAR imaging on tropical islands.

Soufrière Hills volcano on Montserrat in the West Indies showed five episodes of magma extrusion and as many pauses in its 25years of volcanic activity. This eruptive behaviour exhibited cyclic deformation pattern where extrusive “phases” showed island-wide deflation and all “pauses” have been linked to inflation, the last of which remains ongoing. Several models have been developed over the years; all based on magma intrusion and extrusion, into, or from one or several reservoirs, respectively. Using the entire eruptive history, we demonstrate that both, pauses and phases can be linked to a single magma body. Through extensive numerical modelling, we explore in this presentation some alternative routes to magma intrusion, considering several magmatic processes. These range from crystallisation of magma (second boiling) to pressurisation through a free gas phase, to the extreme case where intrusion of fresh magma has ceased years ago, while the inflation is continuing.

For 24 h we measured continuously the variability of atmospheric refractivity over a volcano on the tropical island of Montserrat using a ground-based radar interferometer. We observed variations in phase that we interpret as due to changing water vapour on the propagation path between the radar and the volcano and we present them here in the context of the behaviour of the atmospheric boundary layer over the island. The water vapour behaviour was forced by diurnal processes, the passage of a synoptic-scale system and the presence of a plume of volcanic gas. The interferometer collected images of amplitude and phase every minute. From pairs of phase images, interferograms were calculated and analyzed every minute and averaged hourly, together with contemporaneous measurements of zenith delays estimated from a network of 14 GPS receivers. The standard deviation of phase at two sites on the volcano surface spanned a range of about 1-5 radians, the lowest values occurring at night on the lower slopes and the highest values during the day on the upper slopes. This was also reflected in spatial patterns of variability. Two-dimensional profiles of radar-measured delays were modelled using an atmosphere with water vapour content decreasing upwards and water vapour variability increasing upwards. Estimates of the effect of changing water vapour flux from the volcanic plume indicate that it should contribute only a few percent to this atmospheric variability. A diurnal cycle within the lower boundary layer producing a turbulence-dominated mixed layer during the day and stable layers at night is consistent with the observed refractivity.

For almost 20 years, Soufrière Hills Volcano, Monsterrat, has been in a state of volcanic unrest. Intermittent periods of dome building have been punctuated by explosive eruptions and dome collapse events, endangering the lives of the inhabitants of the island. To date, there have been numerous phases to the activity, with the current activity designated Pause 5. There has not been any active magma extrusion since February 2010, and the last significant explosive (ash-venting) event occurred in March 2012. However, the volcano continues to emit an average of 374t/d SO2 and shows signs of deformation.

While ascending in the plumbing system of volcanoes, magma undergoes decompression at rates spanning several orders of magnitude and set by a number of factors internal and external to the volcano. Slow decompression generally results in an effusive or mildly explosive expansion of the magma, but counterexamples of sudden switches from effusive to explosive eruptive behavior have been documented at various volcanoes worldwide. The mechanisms involved in this behavior are currently debated, in particular for basaltic magmas. Here, we explore the interplay between decompression rate and vesiculation vigor by decompressing a magma analogue obtained by dissolving pine resin into acetone in varying proportions. Analogue experiments allow direct observations of the processes of bubble nucleation and growth, flow dynamics, and fragmentation that is not currently possible with magmatic systems. Our mixtures contain solid particles, and upon decompression, nucleation of acetone bubbles is observed. We find that mixtures with a high acetone content, containing smaller and fewer solid particles, experience strong supersaturation and fragment under very slow decompressions, despite having low viscosity, while mixtures with lower acetone content, with more and larger solid particles, degas efficiently without fragmentation. We interpret our results in terms of delayed bubble nucleation due to a lack of efficient nucleation sites. We discuss how a similar mechanism might induce violent, explosive expansion in volatile‐rich and poorly crystalline low‐silica magmas, by analogy with the behavior of rhyolitic magmas.