MYGALE: Modelling the phYsical and chemical Gradients of hydrothermal ALteration for warning systems of flank collapse at Explosive volcanoes

Project summary

Project ANR-21-CE49-0010

Flank collapse represents a significant volcanic hazard. Hydrothermal alteration is considered to promote volcano instability, but there are few data and models to robustly assess this hypothesis. MYGALE is a multidisciplinary and collaborative project that will combine laboratory measurements, geophysical techniques, and modelling to assess the role of alteration on the stability of La Soufrière de Guadeloupe (France). Time-lapse field geophysical measurements will map the extent and evolution of alteration, experiments will provide physical property data for altered rocks and timescales of alteration, and large-scale 4D numerical modelling will assess the influence of alteration on volcano stability by combing the geophysical and upscaled laboratory data. Working closely with the volcano observatory in Guadeloupe, MYGALE aims at designing optimised monitoring networks to better mitigate volcanic hazards. The results of MYGALE will be applicable for hazardous volcanoes worldwide.

MYGALE project coordinator


Institut Terre et Environnement de Strasbourg, ITES

Mike HEAP 
Patrick BAUD 
Bertrand RENAUDIE 

Institut de Physique du Globe de Paris, IPGP

Jean-Christophe KOMOROWSKI
Vincent ROBERT
Jean-Bernard de CHABALIER
Chagnon GLYNN

Institut des Sciences de la Terre d'Orléans

Caroline MARTEL

Other named team members

Lydie GAILLER (Université Clermont Auvergne, France)
Albert GILG (Technical University of Munich, Germany)
Tobias BAUMANN (University of Mainz, Germany)
Marlène VILLENEUVE (University of Leoben, Austria)

Additional collaborators

Claire HARNETT (University College Dublin, Ireland)
Alexandra KUSHNIR (EPFL, Switzerland)

MYGALE project goals

MYGALE aims to solve the following:

WP 1 What is the extent of the alteration and how does it change with time? This will be achieved by performing 3D electrical tomography surveys, a geophysical method particularly adept at mapping alteration zones, in each of the four years of the project.

WP 2 How long does it take to alter volcanic rocks? We will perform high-temperature, high-pressure flow-through alteration experiments and measure the mineral content and physical properties of the run products to understand timescales of alteration.

WP 3 What does alteration do to the physical properties of volcanic rocks? We will perform systematic physical and mechanical property analysis of variably-altered (including pristine samples) and variably-porous rocks collected from La Soufrière.

WP 4 How does alteration influence large-scale volcano stability (flank stability modelling combining geophysics and laboratory data)? Using the results from the other three work packages, we will perform large-scale volcano stability models using 3D volcano models created using the electrical tomography data (WP1), including models in which we expand the alteration zones based on our measured alteration rates (WP2), and upscaled physical and mechanical properties (WP3). The results of these models will be used to provide the volcano observatory with valuable information to improve the uncertainty in decision-making on a significant volcanic hazard.


[11] M. D. Jackson, M. J. Heap, G. Vola, M. Ardit, J. M. Rhodes, J. G. Peterson, N. Tamura, M. T. Gudmundsson (2024). Material and Mechanical Properties of Young Oceanic Basalt, Surtsey Volcano, Iceland. GSA Bulletin.

[10] Heap, M. J., Harnett, C., Farquharson, J., Baud, P., Rosas-Carbajal, M., Komorowski, J. C., Violay, M.E., Gilg, H.A., & Reuschlé, T. (2023). The influence of water-saturation on the strength of volcanic rocks and the stability of lava domes. Journal of Volcanology and Geothermal Research, 107962.

[9] Heap, M.J., Harnett, C.E., Nazarbayov, T., Heng, Z., Baud, P., Xu, T., Rosas-Carbajal, M. and Komorowski, J.C. (2023). The influence of heterogeneity on the strength of volcanic rocks and the stability of lava domes. Bulletin of Volcanology, 85(9), 49.

[8] Heap, M.J., Wadsworth, F.B., and Jessop, D.E. (2023). The thermal conductivity of unlithified granular volcanic materials: The influence of hydrothermal alteration and degree of water saturation. Journal of Voclanology and Geothermal Research, 107775.

[7] Kereszturi, G., Heap, M. J., Schaefer, L.N., Darmawan, H., Deegan, F.M., Kennedy, B., Komorowski, J.-C., Mead, S., Rosas-Carbajal, M., Ryan, A., Troll, V.R., Villeneuve, M., & Walter, T.R. (2023). Porosity, strength, and alteration – Towards a new volcano stability assessment tool using VNIR-SWIR reflectance spectroscopy. Earth and Planetary Science Letters, 602, 117929.

[6] Harnett, C.E., Heap, M.J., Troll, V.R., Deegan, F.M., and Walter, T. (2022). Large-scale lava dome fracturing as a result of concealed weakened zones. Geology.

[5] Heap, M.J., Troll, V.R., Harris, C., Gilg, H.A., Moretti, R.Rosas-Carbajal, M., Komorowski, J.-C., and Baud, P. (2022). Whole-rock oxygen isotope ratios as a proxy for the strength and stiffness of hydrothermally altered volcanic rocks. Bulletin of Volcanology, 84:74,

[4] Heap, M.J., Harnett, C.E., Wadsworth, F.B., Gilg, H.A., Carbillet, L., Rosas-Carbajal, M., Komorowski, J.-C., Baud, P., Troll, V.R., Deegan, F.M., Holohan, E.P., and Moretti, R. (2022). The tensile strength of hydrothermally altered volcanic rocks. Journal of Volcanology and Geothermal Research, 428, 107576.

[3] Darmawan, H., Troll, V.R., Walter, T.R., Deegan, F.M., Geiger, H., Heap, M.J., Seraphine, N., Harris, C., Humaida, H., and Mueller, D. (2022). Hidden mechanical weaknesses within lava domes provided by buried high-porosity hydrothermal alteration zones. Scientific Reports, 12, 3202.

[2] Heap, M.J., Jessop, D.E., Wadsworth, F.B., Rosas-Carbajal, M., Komorowski, J.-C.Gilg, H.A., Aron, N., Gential, L., Goupil, M., Masson, M., Hervieu, L., Kushnir, A.R.L., Baud, P., Carbillet, L., Ryan, A.G., and Moretti, R. (2021). The thermal properties of hydrothermally altered andesites from La Soufrière de Guadeloupe (Eastern Caribbean). Journal of Volcanology and Geothermal Research, 421, 107444.

[1] Heap, M.J., Baumann, T.Rosas-Carbajal, M., Komorowski, J.-C.Gilg, H.A.Villeneuve, M.Moretti, R.Baud, P., Harnett, C., Reuschlé, T. (2021) Alteration-induced volcano instability at La Soufrière de Guadeloupe (Eastern Caribbean). Journal of Geophysical Research: Solid Earth, 126, 8, e2021JB022514.