Richard A. Herd

University of East Anglia

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Jenni Barclay

University of East Anglia

Marie Edmonds

University of Cambridge

B. Voight

Pennsylvania State University

G. S. Mattioli

The University of Texas at Arlington

R. S. J. Sparks

University of Bristol

Ralf Gertisser

Keele University

Katie Preece

Swansea University

G. E. Norton

British Geological Survey

Derek Elsworth

Pennsylvania State University

S. R. Young

RELX Group (United States)

Cooperative Institutions

Montserrat Volcano Observatory

University of Cambridge

University of Bristol

United States Geological Survey

Centre National de la Recherche Scientifique

British Geological Survey

University of East Anglia

Pennsylvania State University

University of the West Indies

University of Oxford

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Melting, Differentiation and Degassing at the Pantelleria Volcano, Italy

Journal of Petrology (2012)

David A. Neave Gareth N. Fabbro Richard A. Herd Chiara Maria Petrone Marie Edmonds

We present the results of the first systematic study of melt compositions at Pantelleria, based on both melt inclusions and matrix glasses in pantellerites from 10 eruptions during the last eruptive cycle (<45 kyr). We present major and trace element compositions, as well as data on the volatiles sulphur (S), fluorine (F), chlorine (Cl), water (H2O), carbon dioxide (CO2) and lithium (Li) Rare earth element (REE) compositions were inverted using the program INVMEL to establish the melt fraction vs depth relationship in the Pantellerian mantle source region. Inversion indicates that melts are generated by ∼1·7% melting of a light rare earth element (LREE)-enriched mantle source. The source lies principally within the spinel–garnet transition zone, which, on the basis of trace element ratios, shows some affinity to the source of North African magmatism. Major and trace element data indicate a gap in melt compositions at intermediate compositions, consistent with previously published whole-rock data. This gap rules out the possibility of explaining chemical variability in the Pantelleria lavas merely by changes in the crystal content of the magmas. Principal component analysis of major element glass compositions shows that the liquid line of descent for mafic melt compositions is controlled by clinopyroxene, plagioclase, magnetite and olivine crystallization. Alkali feldspar, clinopyroxene, ilmenite and olivine or aenigmatite crystallization controls the liquid line of descent for the silicic melt compositions, with aenigmatite broadly replacing olivine in the most evolved magmas. Trace element modelling indicates that 96% fractional crystallization is required to generate pantellerites from alkali basalts at Pantelleria (through trachytes, generated after 76% fractional crystallization). We have measured pantellerite volatile concentrations in melt inclusions and in matrix glasses from a variety of eruptions. Melt inclusions, on average, contain 350 ppm S, 3500 ppm F and 9000 ppm Cl. We have measured up to 4·9 wt % H2O and 150 ppm CO2 in melt inclusions. Li–H2O systematics and Cl abundances in melt inclusions are consistent with partitioning of Li and Cl into a subcritical hydrosaline fluid at low pressures. The volatiles H2O and CO2 are used to estimate melt equilibration pressures, which reach a maximum of 1·5 kbar. Temperatures of 800°C are calculated for the most evolved pantellerites, using published feldspar–melt geothermometers, and up to 870°C for the least evolved samples. Low melt viscosities are calculated for the range of pantellerite compositions observed and may account for rapid differentiation by crystal settling. Stable density stratification of the magma chamber is reflected in the eruption of generally progressively more fractionated compositions after the Green Tuff eruption during the last eruptive cycle. Some anomalies in this trend may be explained by variation in the relative rates of eruption vs fractionation. The density stratification is expected to be enhanced and further stabilized by the efficient migration of a fluid phase to the roof of the magma chamber. The sulphur data are used in combination with published experimental partitioning data for peralkaline rhyolites to estimate the sulphur yield to the atmosphere for a large pantelleritic eruption similar to the Green Tuff. This is expected to be markedly higher than for a similar-sized metaluminous rhyolitic or dacitic eruption, mainly owing to the higher bulk sulphur content, lower fluid–melt partition coefficients, and rapid differentiation and vapour phase segregation in the magma chamber.

Silicic

Incompatible element

Trace element

Fractional crystallization (geology)

Rare-earth element

Primitive mantle

10.1093/petrology/egr074

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Citations (77)

The 2010 Eruption of Merapi Volcano, Java, Indonesia: Petrological Insights into Magma Dynamics and Eruptive Behaviour

EGUGA (2012)

Ralf Gertisser Heather Handley Katie Preece Matthew T. Reagan Kim Berlo

Phreatic eruption

Source

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Deposits from the 12 July Dome Collapse and Explosive Activity at Soufriere Hills Volcano, 12-15 July 2003

AGUFM (2003)

Marie Edmonds Richard A. Herd M. Strutt Crystal P. Mann

Dome (geology)

Source

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Citations (0)

Hazard implications of small-scale edifice instability and sector collapse: a case history from Soufrière Hills Volcano, Montserrat

Geological Society London Memoirs (2002)

S. R. Young B. Voight Jenni Barclay Richard A. Herd Jean‐Christophe Komorowski

Abstract During the 1995 to 1998 phase of dome growth at Soufrière Hills Volcano on Montserrat, we documented instability of the steep southern rim of English's Crater, known as Galway's Wall. The horseshoe-shaped English's Crater provided good evidence for previous sector collapses, and assessments undertaken in late 1996 anticipated the possibility of a partial sector collapse and a SW-directed explosion, hazards previously unrecognized on Montserrat. A change from predominantly endogenous to exogenous growth of the lava dome at the end of 1996 eased the stress on the southern sector. However, rapid dome growth in November and December 1997 led to severe reloading and eventual sector failure at the base of the buried Galway's Wall and in the adjacent hot-spring area. This failure resulted in the debris avalanche and lateral blast of 26 December 1997. Similar sector collapses at a number of small volcanoes in the Caribbean, as well as worldwide, are evidence that edifice instability develops commonly in dome-forming eruptions. The hazards from a sector collapse and a consequent lateral blast are extreme, and monitoring operations and disaster planning at such volcanoes should focus on these, as well as on the more common hazards of conventional pyroclastic flows associated with dome growth.

Volcanic hazards

Hazard map

10.1144/gsl.mem.2002.021.01.16

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Citations (24)

Rainfall‐induced volcanic activity on Montserrat

Geophysical Research Letters (2002)

Adrian J. Matthews Jenni Barclay Simon Carn Gary M. Thompson Jan Alexander

Dome‐forming volcanic eruptions cyclically extrude bodies of lava over several months, which then become gravitationally unstable and collapse, generating pyroclastic flows. On 29 July 2001 extreme rainfall over Montserrat coincided with a major collapse of the Soufrière Hills lava dome. We present rainfall and seismic records that demonstrate, for the first time, a relationship between intense rainfall and lava dome collapse, with associated pyroclastic flow generation. After seven months of little rain and a period of sustained dome growth, the onset of intense rain was followed within hours by dome collapse and pyroclastic flows. The large‐scale weather system responsible for the rain was identifiable in satellite images and predicted by meteorological forecasts issued 60 hours prior to the volcanic activity. It is suggested that weather prediction of intense rainfall be incorporated with existing geophysical and geochemical measurements to improve warnings of these hazardous events.

Lava dome

Dome (geology)

10.1029/2002gl014863

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Citations (101)

Magma production and growth of the lava dome of the Soufriere Hills Volcano, Montserrat, West Indies: November 1995 to December 1997

Geophysical Research Letters (1998)

R. S. J. Sparks S. R. Young Jenni Barclay Eliza S. Calder Paul Cole

From November 1995 to December 1997 a total volume of 246 × 10 6 (DRE) m³ of andesite magma erupted, partitioned into 93 × 10 6 m³ of the dome, 125 × 10 6 m³ of pyroclastic flow deposits and 28 × 10 6 m³ of explosive ejecta. In the first 11 weeks magma discharge rate was low (0.5 m³/s). From February 1996 to May 1997 discharge rates have averaged 2.1 m³/s, but have fluctuated significantly and have increased with time. Three pulses lasting a few months can be recognised with discharge rates reaching 3 to 8 m³/s. Short term pulsations in growth lasting a few days reach discharge rates of over 10 m³/s and there are periods of days to a few weeks when dome growth is < 0.5 m³/s. Discharge rate increased from May 1997 with an average rate of 7.5 m³/s to December 1997. The observations indicate an open magmatic system.

Dome (geology)

Lava dome

Magma chamber

10.1029/98gl00639

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Citations (154)

Numerical simulation of the December 1997 Debris Avalanche in Montserrat, Lesser Antilles

Geophysical Research Letters (2001)

P. Heinrich Georges Boudon Jean‐Christophe Komorowski R. S. J. Sparks Richard A. Herd

Emplacement of a debris avalanche in the White River valley of southern Montserrat (Lesser Antilles), on 26 December 1997, was caused by sector failure of the south flank of the active Soufriere Hills volcano. Pre‐ and post‐emplacement surveys of the region indicate a debris avalanche deposit volume of about 40–50 × 10 6 m³. This avalanche is modeled as the gravitational flow of a homogeneous continuum governed by a basal friction law. Mass and momentum equations are depth‐averaged over the slide thickness. Numerical results show that the observed distribution of debris and duration of emplacement is simulated well for a Coulomb‐type friction law with a dynamic friction coefficient dependent upon the thickness and the velocity of the flowing mass.

Debris flow

10.1029/2001gl012968

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Citations (48)

Caught in the act: Implications for the increasing abundance of mafic enclaves during the recent eruptive episodes of the Soufrière Hills Volcano, Montserrat

Geophysical Research Letters (2010)

Jenni Barclay Richard A. Herd Benjamin R. Edwards T. Christopher E. J. Kiddle

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.

Porphyritic

Lava dome

Basaltic andesite

10.1029/2010gl042509

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Citations (40)

Tsunami generated by the volcano eruption on July 12-13 at Montserrat, Lesser Antilles

Efim Pelinovsky Narcisse Zahibo P. N. Dunkley Marie Edmonds Richard A. Herd

A major collapse of a lava dome occurred at the Soufriere Hills Volcano (Montserrat, Lesser Antilles), culminating late in the evening (11:35 PM local time) on July 12, 2003 (03:35 GMT on 13 July). This generated a tsunami, which was recorded on Montserrat 2-4 km from the generating area and Guadeloupe, 50 km from Montserrat. Results of field surveys are presented. Tsunami wave height on Montserrat may have been about 4 m according to the location of a strandline of charred trees and other floating objects at Spanish Point on the east coast of the island. The wave height on Guadeloupe according to “direct” witnesses was about 0.5-1 m at Deshaies and near Plage de la Perle. The tsunami at Deshaies caused the scattering of boats as confirmed by fishermen and local authorities. Data from the field survey are in agreement with the predicted tsunami scenario obtained by numerical simulation.

Dome (geology)

Submarine volcano

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Citations (46)

Geochemical evidence for relict degassing pathways preserved in andesite

Earth and Planetary Science Letters (2013)

Melissa Plail Marie Edmonds Madeleine C. S. Humphreys Jenni Barclay Richard A. Herd

Lava dome

10.1016/j.epsl.2013.10.044

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Citations (32)