Compaction and Permeability Evolution of Tuffs From Krafla Volcano (Iceland)

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Heap, Michael, Bayramov, Kamal, Meyer, Gabriel, Violay, Marie, Reuschlé, Thierry, Baud, Patrick, Gilg, H. Albert, Harnett, Claire, Kushnir, Alexandra, Lazari, Francesco, Mortensen, Anette
• Other Authors: Institut Terre Environnement Strasbourg (ITES), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Ecole Polytechnique Fédérale de Lausanne (EPFL), French-Azerbaijani University (UFAZ), Technical University of Munich (TUM), University College Dublin Dublin (UCD), LANDSVIRKJUN, ANR-20-SFRI-0012,STRAT'US,Façonner les talents en formation et en recherche à l'Université de Strasbourg(2020), ANR-10-IDEX-0002,UNISTRA,Par-delà les frontières, l'Université de Strasbourg(2010), ANR-21-CE49-0010,MYGALE,Modélisation phYsico-chimique des Gradients de l'ALtération hydrothermale: sentinelle de la dynamique d'instabilité gravitaire des volcans Explosifs(2021), European Project: 101118491,ROTTnROCK, European Project: 757290,BEFINE
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; Krafla; Iceland
• Online Access: https://hal.science/hal-04670787; https://hal.science/hal-04670787/document; https://hal.science/hal-04670787/file/JGR%20Solid%20Earth%20-%202024%20-%20Heap%20-%20Compaction%20and%20Permeability%20Evolution%20of%20Tuffs%20From%20Krafla%20Volcano%20Iceland.pdf; https://doi.org/10.1029/2024JB029067

International audience Abstract Pressure and stress perturbations associated with volcanic activity and geothermal production can modify the porosity and permeability of volcanic rock, influencing hydrothermal convection, the distribution of pore fluids and pressures, and the ease of magma outgassing. However, porosity and permeability data for volcanic rock as a function of pressure and stress are rare. We focus here on three porous tuffs from Krafla volcano (Iceland). Triaxial deformation experiments showed that, despite their very similar porosities, the mechanical behavior of the three tuffs differs. Tuffs with a greater abundance of phyllosilicates and zeolites require lower stresses for inelastic behavior. Under hydrostatic conditions, porosity and permeability decrease as a function of increasing effective pressure, with larger decreases measured at pressures above that required for cataclastic pore collapse. During differential loading in the ductile regime, permeability evolution depends on initial microstructure, particularly the initial void space tortuosity. Cataclastic pore collapse can disrupt the low‐tortuosity porosity structure of high‐permeability tuffs, reducing permeability, but does not particularly influence the already tortuous porosity structure of low‐permeability tuffs, for which permeability can even increase. Increases in permeability during compaction, not observed for other porous rocks, are interpreted as a result of a decrease in void space tortuosity as microcracks surrounding collapsed pores connect adjacent pores. Our data underscore the importance of initial microstructure on permeability evolution in volcanic rock. Our data can be used to better understand and model fluid flow at geothermal reservoirs and volcanoes, important to optimize geothermal exploitation and understand and mitigate volcanic hazards.