The memory of volcanic waters: Shallow magma degassing revealed by halogen monitoring in thermal springs of La Soufrière volcano (Guadeloupe, Lesser Antilles)

Villemant, Benoı̂t; Hammouya, G.; Michel, A.; Semet, Michel P.; Komorowski, Jean‐Christophe; Boudon, Georges; Cheminée, J. L.

doi:10.1016/j.epsl.2005.05.013

Cited by 74 publications

(144 citation statements)

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“…These questions will be just as pressing if, in the near future, the signs of volcanic unrest manifested since 1992 in Guadeloupe Villemant et al 2005) were to escalate. The public clashes in 1976 left a legacy of loss of trust in scientists and authorities there.…”

Section: Introductionmentioning

confidence: 99%

“…Any future crisis will need to be managed with care and a transparent and robust approach to information sharing if trust is to be fully restored. Villemant et al (2005) remark that it remains very difficult to interpret monitoring data in terms of deep volcanic processes, for example to identify or differentiate between magmatic activity and purely hydrothermal activity. At the time of the 1976 crisis, knowledge of the style and magnitude of past eruptive activity of La Soufrière was limited, and multi-parameter monitoring data (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Retrospective analysis of uncertain eruption precursors at La Soufrière volcano, Guadeloupe, 1975–77: volcanic hazard assessment using a Bayesian Belief Network approach

et al. 2014

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Background: Scientists monitoring active volcanoes are increasingly required to provide decision support to civil authorities during periods of unrest. As the extent and resolution of monitoring improves, the process of jointly interpreting multiple strands of indirect evidence becomes increasingly complex. Similarities with uncertainties in medical diagnosis suggest a formal evidence-based approach, whereby monitoring data are analysed synoptically to provide probabilistic hazard forecasts. A statistical tool to formalize such inferences is the Bayesian Belief Network (BBN). By explicitly representing conditional dependencies between the volcanological model and observations, BBNs use probability theory to treat uncertainties in a rational and auditable manner, as warranted by the strength of the scientific evidence. A retrospective analysis is given for the 1976 Guadeloupe crisis, using a BBN to provide inferential assessment of the state of the evolving magmatic system and probability of incipient eruption. Conditional dependencies are characterized quantitatively by structured expert elicitation. Results: Analysis of the available monitoring data suggests that at the height of the crisis the probability of magmatic intrusion was high, in accordance with scientific thinking at the time. The corresponding probability of magmatic eruption was elevated in July and August 1976 and signs of precursory activity were justifiably cause for concern. However, collective uncertainty about the future course of the crisis was also substantial. Of all the possible scenarios, the most likely outcome evinced by interpretation of observations on 31 August 1976 was 'no eruption' (mean probability 0.5); the chance of a magmatic eruption/blast had an estimated mean probability of~0.4. There was therefore no evidential basis for asserting one scenario to be significantly more likely than another.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Retrospective analysis of uncertain eruption precursors at La Soufrière volcano, Guadeloupe, 1975–77: volcanic hazard assessment using a Bayesian Belief Network approach

et al. 2014

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“…Since then, intense hydrothermal activity has persisted at La Soufrière, including six phreatic eruptive phases. Volcanic gases are persistently released as fumaroles on and around the lava dome (Brombach et al, 2000;Ruzié et al, 2012) and as dissolved and/or bubbling gases in thermal springs around the volcanic edifice (Villemant et al, 2005;Ruzié et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Helium isotope systematics of volcanic gases and thermal waters of Guadeloupe Island, Lesser Antilles

Jean‐Baptiste

Allard

Fourré

et al. 2014

Journal of Volcanology and Geothermal Research

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The island of Guadeloupe is located in the middle of the 850 km long Lesser Antilles island arc. Present-day volcanic and geothermal activity is concentrated in two systems both located in the southwestern part of the island (Basse Terre): the La Soufrière volcanic complex and the Bouillante hydrothermal system, some 20 km to the northwest of the volcano. We report here the largest isotopic data set for helium isotopes in hydrothermal gases and waters from both systems, acquired between 1980 and 2012. 3 He/ 4 He ratios in the fumarolic gases of La Soufrière volcano have been quite homogeneous and stable over the last thirty years. The average ratio of 8.2 ± 0.2 R a confirms that the volcano is tapping a MORB-like mantle source. In contrast, the nearby Bouillante geothermal system displays a much lower 3 He/ 4 He ratio (4.5 ± 0.1 R a ). He-C elemental and isotopic relationships show that both systems are actually fed by the same magmatic source, and that their marked difference in 3 He/ 4 He results from the 4 He contamination of the Bouillante deep aquifer by the surrounding wallrock. This conclusion is strengthened by the spatial distribution of 3 He/ 4 He ratios which shows that La Soufrière fumaroles and the Bouillante geothermal system are the two end-members of a spatial trend of decreasing 3 He/ 4 He ratio with distance from La Soufrière summit dome, implying an increasing addition of radiogenic 4 He from the host rocks away from the present-day active volcanic edifice.

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“…Its last magmatic eruption is estimated to have been 1530 AD Komorowski et al, 2008) and, since then, six phreatic eruptions have occurred: 1690, 1797-1798, 1812, 1836-1837, 1956, and 1976-1977. The last unrest was interpreted as a still-born magmatic eruption by Feuillard et al (1983) (see also Villemant et al, 2005). A renewal of activity started in 1992, and several parameters are currently slowly increasing: intensification of shallow seismicity with long-period events, spatial extension and flux increase of the fumarolic activity at the summit of the volcano, changes in the chemical composition of the gas (sulfur and chlorine), and increases the temperature at several hydrothermal spots.…”

Section: Volcano Monitoring In the Lesser Antillesmentioning

confidence: 99%

Muon tomography: Plans for observations in the Lesser Antilles

et al. 2010

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The application of muon tomography to monitor and image the internal structure of volcanoes in the Lesser Antilles is discussed. Particular focus is directed towards the three volcanoes that fall under the responsibility of the Institut de Physique du Globe of Paris, namely La Montagne Pelée in Martinique, La Soufrière in Guadeloupe, and the Soufrière Hills in Montserrat. The technological criteria for the design of portable muon telescopes are presented in detail for both their mechanical and electronic aspects. The detector matrices are constructed with scintillator strips, and their detection characteristics are discussed. The tomography inversion is presented, and its distinctive characteristics are brie y discussed. Details are given on the implementation of muon tomography experiments on La Soufrière in Guadeloupe.

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The memory of volcanic waters: Shallow magma degassing revealed by halogen monitoring in thermal springs of La Soufrière volcano (Guadeloupe, Lesser Antilles)

Cited by 74 publications

References 32 publications

Retrospective analysis of uncertain eruption precursors at La Soufrière volcano, Guadeloupe, 1975–77: volcanic hazard assessment using a Bayesian Belief Network approach

Retrospective analysis of uncertain eruption precursors at La Soufrière volcano, Guadeloupe, 1975–77: volcanic hazard assessment using a Bayesian Belief Network approach

Helium isotope systematics of volcanic gases and thermal waters of Guadeloupe Island, Lesser Antilles

Muon tomography: Plans for observations in the Lesser Antilles

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