Abstract
This study investigates how 3D microstructural variability influences vesicular lavas, which are globally widespread and important geo-resources. A lava block from S. Miguel Island (Azores, Portugal) was oriented along three orthogonal directions defined by pore elongation and analysed using laboratory methods. Mercury intrusion porosimetry and X-ray microtomography (µCT) characterised pore networks, and mechanical properties were measured through time-resolved in situ µCT tests. The lava sample has a heterogeneous, bimodal pore size distribution, comprising coalescent pores formed during magma ascent and lava emplacement, producing variability in 3D rock properties. Pore and throat size and heterogeneity distributions govern connected porosity and permeability across orientations, whereas directional variations in strength are influenced by the distribution of large, edge-proximal pores. Ultrasonic velocities and capillary absorption show limited directional variability at the mesoscale. Capillary water absorption is moderate and follows the Sharp Front model; pores larger than 1 mm contribute little to absorption, promoting predominantly gravity-driven flow despite low permeability. Our investigation demonstrates that strength variability in vesicular lavas is controlled by pore spatial distribution (rather than orientation alone), while large (> 1 mm) pores suppress directional capillary effects. This study also shows that similar multiscale approaches allow efficient exploration of pore-scale heterogeneity in volcanic rocks.
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The main data generated and analysed during this study are included in this published article. Further data can be provided from the corresponding author on reasonable request.
References
Shea, T. Bubble nucleation in magmas: a dominantly heterogeneous process? J. Volcanol Geotherm. Res. 343, 155–170. https://doi.org/10.1016/j.jvolgeores.2017.06.025 (2017).
Rodríguez-Losada, J. A. et al. Geomechanical parameters of intact rocks and rock masses from the Canary Islands: implications on their flank stability. J. Volcanol Geotherm. Res. 182, 67–75. https://doi.org/10.1016/j.jvolgeores.2009.01.032 (2009).
Pereira, M. L. et al. A multi-method approach in the physical and mechanical assessment of lava rocks with distinct microstructure. Eng. Geol. 346, 107907. https://doi.org/10.1016/j.enggeo.2025.107907 (2025).
Bubeck, A., Walker, R. J., Healy, D., Dobbs, M. & Holwell, D. A. Pore geometry as a control on rock strength. Earth Planet. Sci. Lett. 457, 38–48. https://doi.org/10.1016/j.epsl.2016.09.050 (2017).
Bustos, J. P. A. & Adam, L. Experimental insights into factors influencing Vp/Vs ratios at the Nevado del Ruiz Volcano. Colombia Volcanica. 6, 283–299. https://doi.org/10.30909/06.02.283299 (2023).
Vairé, E., Heap, M. J., Baud, P. & van Wyk, B. Quantifying the physical and mechanical heterogeneity of porous volcanic rocks from the Chaîne des Puys (Massif Central, France). Bull. Volcanol. 86, 49. https://doi.org/10.1007/s00445-024-01742-8 (2024).
Heap, M. J. & Violay, M. E. The mechanical behaviour and failure modes of volcanic rocks: a review. Bull. Volcanol. 83, 33; (2021). https://doi.org/10.1007/s00445-021-01447-2
Heap, M. J. et al. The strength of heterogeneous volcanic rocks: a 2D approximation. J. Volcanol Geotherm. Res. 319, 1–11. https://doi.org/10.1016/j.jvolgeores.2016.03.013 (2016).
Griffiths, L. et al. The influence of pore geometry and orientation on the strength and stiffness of porous rock. J. Struct. Geol. 96, 149–160. https://doi.org/10.1016/j.jsg.2017.02.006 (2017).
Pappalardo, L., Buono, G., Fanara, S. & Petrosino, P. Combining textural and geochemical investigations to explore the dynamics of magma ascent during Plinian eruptions: a Somma–Vesuvius volcano (Italy) case study. Contrib. Mineral. Petrol. 173, 20. https://doi.org/10.1007/s00410-018-1486-x (2018).
Toramaru, A. Vesiculation process and bubble size distributions in ascending magmas with constant velocities. J. Geophys. Res. Solid Earth. 94, 17523–17542. https://doi.org/10.1029/JB094iB12p17523 (1989).
Wasantha, P. L. P., Heng, Z. & Xu, T. Numerical analysis of the effects of vesicle distribution characteristics on the engineering properties of volcanic rocks. J. Rock. Mech. Geotech. Eng. 15, 3094–3104. https://doi.org/10.1016/j.jrmge.2023.09.006 (2023).
Benavente, D. Why pore size is important in the deterioration of porous stones used in the built heritage. Macla 15, 41–42 (2011).
Benavente, D. et al. Predicting water permeability in sedimentary rocks from capillary imbibition and pore structure. Eng. Geol. 195, 301–311. https://doi.org/10.1016/j.enggeo.2015.06.003 (2015).
İnce, İ., Bozdağ, A., Barstuğan, M. & Fener, M. Evaluation of the relationship between the physical properties and capillary water absorption values of building stones by regression analysis and artificial neural networks. J. Build. Eng. 42, 103055 (2021).
Cueto, N. et al. Water transport in lapilli tuff from Madeira Island, Portugal: implications on degradation mechanisms and durability. In Atas do 16º Congresso Nacional de Geotecnia (2018).
Vargas, C. A. et al. Breathing of the Nevado del Ruiz volcano reservoir, Colombia, inferred from repeated seismic tomography. Sci. Rep. 7, 46094. https://doi.org/10.1038/srep46094 (2017).
Marques, R., Zêzere, J., Trigo, R., Gaspar, J. & Trigo, I. Rainfall patterns and critical values associated with landslides in Povoação County (São Miguel Island, Azores): relationships with the North Atlantic Oscillation. Hydrol. Process. 22, 478–494. https://doi.org/10.1002/hyp.6879 (2008).
Heap, M. J. et al. The influence of water saturation on the strength of volcanic rocks and the stability of lava domes. J. Volcanol Geotherm. Res. 444, 107962. https://doi.org/10.1016/j.jvolgeores.2023.107962 (2023).
Cueto, N., de Sousa, J. V., Perneta, J. P. S. & Meza, R. Capillary imbibition behaviour in volcanic rocks from Madeira Island, Portugal: preliminary results. In New Challenges in Rock Mechanics and Rock Engineering 1117–1123CRC Press, (2024).
Cueto, N. et al. Hydric and mechanical properties assessment of basalts from Madeira Island, Portugal. In Geotechnical Engineering Challenges to Meet Current and Emerging Needs of Society (eds Guerra, N., Matos Fernandes, M., Ferreira, C., Gomes Correia, A., Pinto, A. & Sêco Pinto, P.) 418–423 (CRC Press, (2024).
Çelik, M. Y. & Kaçmaz, A. U. The investigation of static and dynamic capillary water absorption in porous building stones under normal and saline water conditions. Environ. Earth Sci. 75, 307. https://doi.org/10.1007/s12665-015-5132-x (2016).
Çelik, M. Y. & Sert, M. Assessment of pore size distribution changes in andesite used as building stone under artificial accelerated ageing. Geoheritage 12, 71. https://doi.org/10.1007/s12371-020-00501-3 (2020).
Çelik, M. Y. Characterization of İscehisar andesite (Afyonkarahisar, Turkey) used as a building stone from ancient times to the present. Geoheritage 16, 71. https://doi.org/10.1007/s12371-024-00979-1 (2024).
Dinçer, İ. & Bostancı, M. Capillary water absorption characteristics of Cappadocian ignimbrites and the role of capillarity in their deterioration. Environ. Earth Sci. 78, 7. https://doi.org/10.1007/s12665-018-7993-2 (2019).
Hamon, C. et al. Petrophysical properties of andesites: selecting rock types for Mesoamerican grinding tool production at Turícuaro, Michoacán (Mexico). Geoheritage 17, 6. https://doi.org/10.1007/s12371-024-01052-7 (2025).
Lavallée, Y. & Kendrick, J. E. A review of the physical and mechanical properties of volcanic rocks and magmas in the brittle and ductile regimes. In Forecasting and Planning for Volcanic Hazards, Risks, and Disasters (ed. Papale, P.) 153–238 (Elsevier, 2021).
Trota, A. & Miguel Crustal deformation studies in S. Miguel and Terceira islands (Azores): volcanic unrest evaluation in the Fogo/Congro area (S.). PhD thesis, Universidade dos Açores (2009).
Okada, J. et al. Tectonic and volcanic deformation at São Miguel Island, Azores, observed by continuous GPS analysis 2008–2013. In Volcanic Geology of São Miguel Island (Azores Archipelago), Geol. Soc. Lond. Mem. 44, 295–312 (2015). https://doi.org/10.1144/M44.18
International Society for Rock Mechanics. The complete ISRM suggested methods for rock characterization, testing and monitoring: 1974–2006 (Kozan Ofset, 2007).
European Committee for Standardization. Natural stone test methods: determination of water absorption coefficient by capillarity (EN 1925:2000. (2000).
ASTM International. Standard test method for laboratory determination of pulse velocities and ultrasonic elastic constants of rock 2845–2808 (ASTM D, 2008).
Cueto, N. & Benavente, D. García-del-Cura, M. Influencia de la anisotropía en las propriedades hídricas de rocas. Estudio de rocas dolomíticas brechoides de la Cordillera Bética (España). Geogaceta 40, 315–318 (2006).
Ioannou, I., Hall, C. & Hamilton, A. Application of the sharp front model to capillary absorption in concrete materials with bimodal pore size distribution. In Proc. Int. RILEM Symp. on Concrete Modelling 521–525 (2008).
Ioannou, I., Andreou, A., Tsikouras, B. & Hatzipanagiotou, K. Application of the sharp front model to capillary absorption in a vuggy limestone. Eng. Geol. 105, 20–23 (2009).
Hall, C. & Hoff, W. D. Water transport in brick, stone and concrete 3rd edn (CRC, 2021). https://doi.org/10.1201/9780429352744
Buono, G. et al. Weak crust owing past magmatic intrusions beneath Campi Flegrei identified: the engine for bradyseismic movements? AGU Adv. 6, e2024AV001611. https://doi.org/10.1029/2024AV001611 (2025).
Hughes, E. C. et al. How to fragment peralkaline rhyolites: observations on pumice using combined multi-scale 2D and 3D imaging. J. Volcanol Geotherm. Res. 336, 179–191. https://doi.org/10.1016/j.jvolgeores.2017.02.020 (2017).
Pappalardo, L., Buono, G., Fanara, S. & Petrosino, P. Combining textural and geochemical investigations to explore the dynamics of magma ascent during Plinian eruptions: a Somma–Vesuvius volcano (Italy) case study. Contrib. Mineral. Petrol. 173, 20. https://doi.org/10.1007/s00410-018-1486-x (2018).
PerGeos. The digital rock analysis software: PerGeos user’s guide (Thermo Fisher Scientific, 2021).
Franzson, H. et al. Porosity, density and chemical composition relationships in altered Icelandic hyaloclastites. In Water–Rock Interaction 199–202 (Taylor & Francis Group, (2010).
Tuğrul, A. The effect of weathering on pore geometry and compressive strength of selected rock types from Turkey. Eng. Geol. 75, 215–227. https://doi.org/10.1016/j.enggeo.2004.05.008 (2004).
Benavente, D. et al. Impact of salt and frost weathering on the physical and durability properties of travertines and carbonate tufas used as building material. Environ. Earth Sci. 77, 147. https://doi.org/10.1007/s12665-018-7339-0 (2018).
Cant, J. L. et al. Matrix permeability of reservoir rocks, Ngatamariki geothermal field, Taupo volcanic zone, New Zealand. Geotherm. Energy. 6, 1–28. https://doi.org/10.1186/s40517-017-0088-6 (2018).
Heap, M. J. et al. Microstructural controls on the physical and mechanical properties of edifice-forming andesites at Volcán de Colima, Mexico. J. Geophys. Res. Solid Earth. 119, 2925–2963. https://doi.org/10.1002/2013JB010521 (2014).
Heap, M. J., Xu, T. & Chen, C. F. The influence of porosity and vesicle size on the brittle strength of volcanic rocks and magma. Bull. Volcanol. 76, 856. https://doi.org/10.1007/s00445-014-0856-0 (2014).
Basu, A., Mishra, D. A. & Roychowdhury, K. Rock failure modes under uniaxial compression, Brazilian, and point load tests. Bull. Eng. Geol. Environ. 72, 457–475. https://doi.org/10.1007/s10064-013-0505-4 (2013).
Heap, M. J. et al. The tensile strength of volcanic rocks: experiments and models. J. Volcanol Geotherm. Res. 418, 107348. https://doi.org/10.1016/j.jvolgeores.2021.107348 (2021).
Van Stappen, J. F. et al. Uniaxial compressive strength measurements of limestone plugs and cores: a size comparison and X-ray CT study. Bull. Eng. Geol. Environ. 78, 5301–5310. https://doi.org/10.1007/s10064-018-01448-0 (2019).
Hudson, J. A. & Harrison, J. P. Engineering rock mechanics: an introduction to the principles (Elsevier, 2000).
Collinson, A. S. D. & Neuberg, J. W. Gas storage, transport and pressure changes in an evolving permeable volcanic edifice. J. Volcanol Geotherm. Res. 243, 1–13. https://doi.org/10.1016/j.jvolgeores.2012.06.027 (2012).
Todesco, M., Chiodini, G. & Macedonio, G. Monitoring and modelling hydrothermal fluid emission at La Solfatara (Phlegrean Fields, Italy). J. Volcanol Geotherm. Res. 125, 57–79 (2003).
Stimac, J., Goff, F. & Goff, C. J. Intrusion-related geothermal systems. In The Encyclopedia of Volcanoes 2nd edn (eds Sigurdsson, H., Houghton, B., McNutt, S., Rymer, H. & Stix, J.) 1456 (Academic Press, 2015).
Graue, B., Siegesmund, S. & Middendorf, B. Quality assessment of replacement stones for the Cologne Cathedral: mineralogical and petrophysical requirements. Environ. Earth Sci. 63, 1799–1822. https://doi.org/10.1007/s12665-011-1077-x (2011).
Nara, Y. & Kaneko, K. Study of subcritical crack growth in andesite using the double torsion test. Int. J. Rock. Mech. Min. Sci. 42, 521–530. https://doi.org/10.1016/j.ijrmms.2005.02.001 (2005).
Nara, Y. et al. Effects of relative humidity and temperature on subcritical crack growth in igneous rock. Int. J. Rock. Mech. Min. Sci. 47, 640–646. https://doi.org/10.1016/j.ijrmms.2010.04.009 (2010).
Nara, Y. et al. Influence of relative humidity on fracture toughness of rock: implications for subcritical crack growth. Int. J. Solids Struct. 49, 2471–2481. https://doi.org/10.1016/j.ijsolstr.2012.05.009 (2012).
Atkinson, B. K. Subcritical crack growth in geological materials. J. Geophys. Res. Solid Earth. 89, 4077–4114. https://doi.org/10.1029/JB089iB06p04077 (1984).
Kilburn, C. R. J. & Voight, B. Slow rock fracture as eruption precursor at Soufrière Hills volcano, Montserrat. Geophys. Res. Lett. 25, 3665–3668. https://doi.org/10.1029/98GL01609 (1998).
Acknowledgements
The authors would like to thank Istituto Nazionale di Geofisica e Vulcanologia, Sezione Osservatorio Vesuviano, Faculdade de Ciências da Universidade de Lisboa, Instituto Superior de Engenharia de Lisboa (Microseismology and Rock Physics Laboratory), and Instituto de Geociencias from Universidad Complutense de Madrid for providing the space and resources necessary to conduct the experiments.. The authors also thank the two anonymous reviewers for their constructive comments and revisions.
Funding
Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The project that gave rise to these results received the support of a fellowship from ”la Caixa” Foundation (ID 100010434). The fellowship code is LCF/BQ/DR22/11950029. This project has also received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101131765 (EXCITE2) for Transnational Access conducted at Istituto Nazionale di Geofisica e Vulcanologia – Osservatorio Vesuviano, and from the Portuguese Fundação para a Ciência e Tecnologia, FCT, I.P./MCTES through national funds (PIDDAC): LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020) and UID/50019/2025 (https://doi.org/10.54499/UID/PRR/50019/2025), and UID/PRR2/50019/2025. This research was also supported by the TEC Heritage Programme (TEC-2024/TEC-39) funded by the Autonomous Region of Madrid and the Momentum Project (MMT24-IGEO-01). The funding for these actions/grants and contracts comes from the European Union’s Recovery and Resilience Facility-Next Generation, in the framework of the General Invitation of the Spanish Government’s public business entity Red.es to participate in talent attraction and retention programmes within Investment 4 of Component 19 of the Recovery, Transformation and Resilience Plan.
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All authors contributed to the conception and design of the study. Conceptualization, data curation, formal analysis, investigation, visualization, and writing of the original draft was performed by ML Pereira. V Zanon participated in the sample collection and L Pappalardo, G Buono, A Falasconi, N Cueto, R Fort, C Vázquez-Calvo, and M Moreira contributed to data collection and analysis and provided the needed resources and software. I Fernandes, L Pappalardo, and N Cueto supervised the work. All authors provided critical revisions, read and approved the final manuscript.
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Lava samples were collected exclusively from non-protected areas. Under the applicable regional legislation of the Azores (Decreto Regulamentar Regional n.º 20/2012/A, de 5 de novembro; Decreto Legislativo Regional n.º 10/2019/A, de 22 de maio), no permit or prior authorization is required for geological sampling outside legally protected areas.
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Pereira, M.L., Pappalardo, L., Buono, G. et al. Influence of 3D pore-scale heterogeneity on the physical, water transport, and mechanical properties of vesicular lavas from S. Miguel Island. Sci Rep (2026). https://doi.org/10.1038/s41598-026-47196-0
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DOI: https://doi.org/10.1038/s41598-026-47196-0
