Michal Camejo-Harry

University of Oxford

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Jon Blundy

University of Oxford

Raphaël Grandin

Institut de physique du globe de Paris

Joan L. Latchman

University of the West

Rodrigo Contreras-Arratia

Temuco Catholic University

Elena Melekhova

University of Oxford

Lloyd Lynch

University of the West Indies

G. Ryan

University of the West Indies

Karen Pascal

Montserrat Volcano Observatory

I. J. Hamling

GNS Science

Pablo Euillades

Universidad Nacional de Cuyo

Cooperative Institutions

University of the West Indies

University of Bristol

Montserrat Volcano Observatory

University of the West Indies System

University of Cambridge

University of Oxford

University of Leeds

University of the West

Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics

ETH Zurich

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Widespread slab melting in modern subduction zones

Earth and Planetary Science Letters (2023)

Martijn Klaver Gene M. Yogodzinski Capucine Albert Michal Camejo-Harry Marlina Elburg

Adakite

Silicic

Slab

Peridotite

Protolith

Fractional crystallization (geology)

10.1016/j.epsl.2023.118544

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Citations (7)

Magma evolution beneath Bequia, Lesser Antilles, deduced from petrology of lavas and plutonic xenoliths

Contributions to Mineralogy and Petrology (2018)

Michal Camejo-Harry Elena Melekhova Jon Blundy William Attridge Richard Robertson

Extrusive and intrusive igneous rocks represent different parts of a magmatic system and ultimately provide complementary information about the processes operating beneath volcanoes. To shed light on such processes, we have examined and quantified the textures and mineral compositions of plutonic and cumulate xenoliths and lavas from Bequia, Lesser Antilles arc. Both suites contain assemblages of iddingsitized olivine, plagioclase, clinopyroxene and spinel with rare orthopyroxene and ilmenite. Mineral zoning is widespread, but more protracted in lavas than xenoliths. Plagioclase cores and olivine have high anorthite (An ≤ 98) and low forsterite (Fo ≤ 84) compositions respectively, implying crystallisation from a hydrous mafic melt that was already fractionated. Xenolith textures range from adcumulate to orthocumulate with variable mineral crystallisation sequences. Textural criteria are used to organize the xenoliths into six groups. Amphibole, notably absent from lavas, is a common feature of xenoliths, together with minor biotite and apatite. Bulk compositions of xenoliths deviate from the liquid line of descent of lavas supporting a cumulate origin with varying degrees of reactive infiltration by evolved hydrous melts, preserved as melt inclusions in xenolith crystals. Volatile saturation pressures in melt inclusions indicate cumulate crystallization over a 162–571 MPa pressure range under conditions of high dissolved water contents (up to 7.8 wt% H2O), consistent with a variety of other thermobarometric estimates. Phase assemblages of xenoliths are consistent with published experimental data on volatile-saturated low-magnesium and high-alumina basalts and basaltic andesite from the Lesser Antilles at pressures of 200–1000 MPa, temperatures of 950–1050 °C and dissolved H2O contents of 4–7 wt%. Once extracted from mid-crustal mushes, residual melts ascend to higher levels and undergo H2O-saturated crystallization in shallow, pre-eruptive reservoirs to form phenocrysts and glomerocrysts. The absence of amphibole from lavas reflects instability at low pressures, whereas its abundance in xenoliths testifies to its importance in mid-crustal differentiation processes. A complex, vertically extensive (6 to at least 21 km depth) magmatic system is inferred beneath Bequia. Xenoliths represent fragments of the mush incorporated into ascending magmas. The widespread occurrence of evolved melts in the mush, but the absence of erupted evolved magmas, in contrast to islands in the northern Lesser Antilles, may reflect the relative immaturity of the Bequia magmatic system.

Xenolith

Amphibole

Melt inclusions

Phenocryst

Basaltic andesite

10.1007/s00410-018-1504-z

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Citations (21)

Petrological Evidence for Magma Mobilisation Years Before the 2020/21 Eruption of La Soufrière Volcano, St. Vincent.

Authorea (Authorea) (2025)

Michal Camejo-Harry Jon Blundy Euan Mutch Thomas Hudson J. M. Kendall

10.22541/essoar.173724514.42850941/v1

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Early arc crust formation preserved in the Grenadines archipelago, southern Lesser Antilles arc

Royal Society Open Science (2024)

Michal Camejo-Harry Elena Melekhova Sarah Aufrère Anders J. McCarthy Jon Blundy

Intra-arc diversity in volcanic activity and composition is ubiquitous, but its underlying causes remain largely unresolved in many settings. In this work, we examine such variability in the Grenadines archipelago, southern Lesser Antilles arc. Here, juxtaposed volcanic centres exhibit eruptive longevities and chemistries distinct from northern counterparts in the same arc. Our goal is to explain this deviation by investigating variations in magmatic processes using petrological data from erupted crustal xenoliths and lavas, and interpreting these findings within the context of the archipelago's tectonic history and geophysical structure. Textural analyses of xenoliths reveal crystallization over a wide range of pressure-temperature-melt composition conditions in the crust. Mineral phases display discrete compositional trends pointing towards significant inter-island variability in underlying plumbing systems. The geochemical variety of erupted magmas is reminiscent of the entire arc. We speculate that the Grenadines represents the early onset of subduction forming the modern-day Lesser Antilles arc. Extrusive volcanism initiated as submarine activity. Subsequent uplift eroded the original topography of these volcanic centres following the eventual cessation of volcanism in the Neogene. The positioning of the Grenadines on an elevated platform provides rare modern insight into early arc crust formation not commonly preserved in established active arcs.

Archipelago

Island arc

10.1098/rsos.231914

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Rapid pre-explosion increase in dome extrusion rate at La Soufrière, St. Vincent quantified from synthetic aperture radar backscatter

Earth and Planetary Science Letters (2023)

Edna W. Dualeh S. K. Ebmeier Tim Wright M. P. Poland Raphaël Grandin

The extrusion rate of a lava dome is a critical parameter for monitoring silicic eruptions and forecasting their development. Satellite radar backscatter can provide unique information about dome growth during a volcanic eruption when other datasets (e.g., optical, thermal, ground-based measurements, etc.) may be limited. Here, we present an approach for estimating volcanic topography from individual backscatter images. Using data from multiple SAR sensors we apply the method to the dome growth during the 2021 eruption at La Soufrière, St. Vincent. We measure an average extrusion rate of 1.8 m3s−1 between December 2020 and March 2021 before an acceleration in extrusion rate to 17.5 m3s−1 in the 2 days prior to the explosive eruption on 9 April 2021. We estimate a final dome volume of 19.4 million m3, extrapolated from the SAR sensors, with approximately 15% of the total extruded volume emplaced in the last 2 days. A possible explanation for the acceleration in extrusion rate could be the combined emptying of a conduit and reservoir of older material before the ascent of gas-rich magma in April 2021.

Dome (geology)

Lava dome

Backscatter (email)

10.1016/j.epsl.2022.117980

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Citations (15)

Author response for "Early arc crust formation preserved in the Grenadines archipelago, southern Lesser Antilles arc"

Michal Camejo-Harry Elena Melekhova Sarah Aufrère Anders J. McCarthy Jon Blundy

Archipelago

New Hebrides

Island arc

10.1098/rsos.231914/v2/response1

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Citations (0)

Table S1: Monitoring volcano deformation at La Soufrière, St Vincent during the 2020–21 eruption with insights into its magma plumbing system architecture

Figshare (2023)

Michal Camejo-Harry Karen Pascal Pablo Euillades Raphaël Grandin I. J. Hamling

(a) InSAR time-series used in study; (b) InSAR interferogram data used in study.

Table (database)

10.6084/m9.figshare.22304809

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Monitoring volcano deformation at La Soufrière, St Vincent during the 2020–21 eruption with insights into its magma plumbing system architecture

Geological Society London Special Publications (2023)

Michal Camejo-Harry Karen Pascal Pablo Euillades Raphaël Grandin I. J. Hamling

Abstract 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 Soufrière 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 Soufrière 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.

Dome (geology)

Tiltmeter

10.1144/sp539-2022-270

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Citations (6)

Table S2: Monitoring volcano deformation at La Soufrière, St Vincent during the 2020–21 eruption with insights into its magma plumbing system architecture

Figshare (2023)

Michal Camejo-Harry Karen Pascal Pablo Euillades Raphaël Grandin I. J. Hamling

(a) ALOS-2 data points used for modelling the pre-eruptive (effusive) phase at La Soufrière volcano. Radar image dates are 15/01/2020–13/01/2021. (b) SAOCOM data points used for modelling the syn-eruptive (explosive) phase at La Soufrière volcano. Radar image dates are 06/01/2021–14/03/2022.

Table (database)

10.6084/m9.figshare.22304803

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Citations (0)

Responding to eruptive transitions during the 2020–2021 eruption of La Soufrière volcano, St. Vincent

Nature Communications (2022)

E. P. Joseph Michal Camejo-Harry T. Christopher Rodrigo Contreras-Arratia Stacey Edwards

Abstract 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.

Unrest

10.1038/s41467-022-31901-4

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Citations (48)