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Fracturing and healing of basaltic magmas during explosive volcanic eruptions


The eruption of basaltic magmas dominates explosive volcanism on Earth and other planets within the Solar System. The mechanism through which continuous magma fragments into volcanic particles is central in governing eruption dynamics and the ensuing hazards. However, the mechanism of fragmentation of basaltic magmas is still disputed, with both viscous and brittle mechanisms having been proposed. Here we carry out textural analysis of the products of ten eruptions from seven volcanoes by scanning electron microscopy. We find broken crystals surrounded by intact glass that testify to the brittle fragmentation of basaltic magmas during explosive activity worldwide. We then replicated the natural textures of broken crystals in laboratory experiments where variably crystallized basaltic melt was fragmented by rapid deformation. The experiments reveal that crystals are broken by the propagation of a network of fractures through magma, and that afterwards the fractures heal by viscous flow of the melt. Fracturing and healing affect gas mobility, stress distribution, and bubble and crystal size distributions in magma. Our results challenge the idea that the grain size distribution of basaltic eruption products reflects the density of fractures that initially fragmented the magma and ultimately indicate that brittle fracturing and viscous healing of magma may underlie basaltic explosive eruptions globally.

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Fig. 1: SEM of broken crystals and healing fractures in volcanic particles from different eruptions.
Fig. 2: Fracturing of basaltic melt during fragmentation experiments.
Fig. 3: SEM of experimental products and broken crystals and healing fractures therein.
Fig. 4: Parameters of fractures in broken crystals from eruptions and experiments.
Fig. 5: Processes involved in fragmentation.

Data availability

A selection of 317 microphotographs detailing pyroclast textures related to the fracturing and healing of basaltic magmas in explosive volcanic eruptions and in fragmentation experiments is provided as Supplementary Information and is available at Mendeley Data, V1,, while the entire dataset of more than 2,100 microphotographs is available upon request from J.T. The data used in Fig. 4 and Extended Data Fig. 1 and Extended Data Table 1 are available at Mendeley Data, V1, and presented in the source data provided with this paper.


  1. 1.

    Wilson, L. Volcanism in the solar system. Nat. Geosci. 2, 389–397 (2009).

    Google Scholar 

  2. 2.

    Gonnermann, H. M. Magma fragmentation. Annu. Rev. Earth Planet. Sci. 43, 431–458 (2015).

    Google Scholar 

  3. 3.

    Papale, P. Global time-size distribution of volcanic eruptions on Earth. Sci. Rep. 8, 1–11 (2018).

    Google Scholar 

  4. 4.

    Houghton, B. F. & Gonnermann, H. M. Basaltic explosive volcanism: constraints from deposits and models. Chem. Erde 68, 117–140 (2008).

    Google Scholar 

  5. 5.

    Taddeucci, J., Edmonds, M., Houghton, B., James, M. R. & Vergniolle, S. in The Encyclopedia of Volcanoes 485–503 (Elsevier, 2015).

  6. 6.

    Kueppers, U., Scheu, B., Spieler, O. & Dingwell, D. B. Fragmentation efficiency of explosive volcanic eruptions: a study of experimentally generated pyroclasts. J. Volcanol. Geotherm. Res. 153, 125–135 (2006).

    Google Scholar 

  7. 7.

    Alatorre-Ibargüengoitia, M. A., Scheu, B., Dingwell, D. B., Delgado-Granados, H. & Taddeucci, J. Energy consumption by magmatic fragmentation and pyroclast ejection during Vulcanian eruptions. Earth Planet. Sci. Lett. 291, 60–69 (2010).

    Google Scholar 

  8. 8.

    Cashman, K. V. & Scheu, B. in The Encyclopedia of Volcanoes 459–471 (Elsevier, 2015).

  9. 9.

    Alatorre-Ibargüengoitia, M. A., Delgado-Granados, H. & Dingwell, D. B. Hazard map for volcanic ballistic impacts at Popocatépetl volcano (Mexico). Bull. Volcanol. 74, 2155–2169 (2012).

    Google Scholar 

  10. 10.

    Oikawa, T. et al. Reconstruction of the 2014 eruption sequence of Ontake Volcano from recorded images and interviews the Phreatic Eruption of Mt. Ontake Volcano in 2014 5. Volcanology. Earth Planets Space 68, 68–79 (2016).

    Google Scholar 

  11. 11.

    Cook, R. J., Barron, J. C., Papendick, R. I. & Williams, G. J. Impact on agriculture of the Mount St. Helens eruptions. Science 211, 16–22 (1981).

    Google Scholar 

  12. 12.

    Green, F. H. Y. et al. Is volcanic ash a pneumoconiosis risk? Nature 293, 216–217 (1981).

    Google Scholar 

  13. 13.

    Alvarado, J. A. C. et al. Anthropogenic radionuclides in atmospheric air over Switzerland during the last few decades. Nat. Commun. 5, 3030 (2014).

    Google Scholar 

  14. 14.

    Woolley-Meza, O., Grady, D., Thiemann, C., Bagrow, J. P. & Brockmann, D. Eyjafjallajökull and 9/11: the impact of large-scale disasters on worldwide mobility. PLoS ONE 8, e69829 (2013).

    Google Scholar 

  15. 15.

    Dingwell, D. B. Volcanic dilemma: flow or blow. Science 273, 1054–1055 (1996).

    Google Scholar 

  16. 16.

    Zhang, Y. A criterion for the fragmentation of bubbly magma based on brittle failure theory. Nature 402, 648–650 (1999).

    Google Scholar 

  17. 17.

    Gonnermann, H. M. & Manga, M. Explosive volcanism may not be an inevitable consequence of magma fragmentation. Nature 426, 432–435 (2003).

    Google Scholar 

  18. 18.

    Spieler, O. et al. The fragmentation threshold of pyroclastic rocks. Earth Planet. Sci. Lett. 226, 139–148 (2004).

    Google Scholar 

  19. 19.

    Cordonnier, B. et al. The viscous–brittle transition of crystal-bearing silicic melt: direct observation of magma rupture and healing. Geology 40, 611–614 (2012).

    Google Scholar 

  20. 20.

    Namiki, A. & Manga, M. Transition between fragmentation and permeable outgassing of low viscosity magmas. J. Volcanol. Geotherm. Res. 169, 48–60 (2008).

    Google Scholar 

  21. 21.

    Pioli, L. & Harris, A. J. L. Real-time geophysical monitoring of particle size distribution during volcanic explosions at Stromboli Volcano (Italy). Front. Earth Sci. 7, 1–13 (2019).

    Google Scholar 

  22. 22.

    Jones, T. J., Reynolds, C. D. & Boothroyd, S. C. Fluid dynamic induced break-up during volcanic eruptions. Nat. Commun. 10, 3828 (2019).

    Google Scholar 

  23. 23.

    Büttner, R., Dellino, P. & Zimanowski, B. Identifying magma–water interaction from the surface features of ash particles. Nature 401, 688–690 (1999).

    Google Scholar 

  24. 24.

    Houghton, B. F. et al. The influence of conduit processes on changes in style of basaltic Plinian eruptions: Tarawera 1886 and Etna 122 BC. J. Volcanol. Geotherm. Res. 137, 1–14 (2004).

    Google Scholar 

  25. 25.

    Valentine, G. A., Krier, D., Perry, F. V. & Heiken, G. Scoria cone construction mechanisms, Lathrop Wells volcano, southern Nevada, USA. Geology 33, 629–632 (2005).

    Google Scholar 

  26. 26.

    Moitra, P., Gonnermann, H. M., Houghton, B. F. & Tiwary, C. S. Fragmentation and Plinian eruption of crystallizing basaltic magma. Earth Planet. Sci. Lett. 500, 97–104 (2018).

    Google Scholar 

  27. 27.

    Arzilli, F. et al. Magma fragmentation in highly explosive basaltic eruptions induced by rapid crystallization. Nat. Geosci. 12, 1023–1028 (2019).

    Google Scholar 

  28. 28.

    Zimanowski, B., Wohletz, K., Dellino, P. & Büttner, R. The volcanic ash problem. J. Volcanol. Geotherm. Res. 122, 1–5 (2003).

    Google Scholar 

  29. 29.

    Dellino, P. et al. Ash from the Eyjafjallajökull eruption (Iceland): fragmentation processes and aerodynamic behavior. J. Geophys. Res. Solid Earth 117, B00C04 (2012).

    Google Scholar 

  30. 30.

    Dürig, T., Sonder, I., Zimanowski, B., Beyrichen, H. & Büttner, R. Generation of volcanic ash by basaltic volcanism. J. Geophys. Res. Solid Earth 117, B01204 (2012).

    Google Scholar 

  31. 31.

    Polacci, M., Andronico, D., de’ Michieli Vitturi, M., Taddeucci, J. & Cristaldi, A. Mechanisms of ash generation at basaltic volcanoes: the case of Mount Etna, Italy. Front. Earth Sci. 7, 193 (2019).

    Google Scholar 

  32. 32.

    Owen, J., Shea, T. & Tuffen, H. Basalt, unveiling fluid-filled fractures, inducing sediment intra-void transport, ephemerally: examples from Katla 1918. J. Volcanol. Geotherm. Res. 369, 121–144 (2019).

    Google Scholar 

  33. 33.

    Büttner, R., Dellino, P., Raue, H., Sonder, I. & Zimanowski, B. Stress-induced brittle fragmentation of magmatic melts: theory and experiments. J. Geophys. Res. Solid Earth 111, B08204 (2006).

    Google Scholar 

  34. 34.

    Taddeucci, J., Pompilio, M. & Scarlato, P. Conduit processes during the July–August 2001 explosive activity of Mt. Etna (Italy): inferences from glass chemistry and crystal size distribution of ash particles. J. Volcanol. Geotherm. Res. 137, 33–54 (2004).

    Google Scholar 

  35. 35.

    Bindeman, I. N. Fragmentation phenomena in populations of magmatic crystals. Am. Mineral. 90, 1801–1815 (2005).

    Google Scholar 

  36. 36.

    Kennedy, B. et al. Conduit implosion during Vulcanian eruptions. Geology 33, 581–584 (2005).

    Google Scholar 

  37. 37.

    Miwa, T. & Geshi, N. Decompression rate of magma at fragmentation: inference from broken crystals in pumice of Vulcanian eruption. J. Volcanol. Geotherm. Res. 227–228, 76–84 (2012).

    Google Scholar 

  38. 38.

    van Zalinge, M. E., Cashman, K. V. & Sparks, R. S. J. Causes of fragmented crystals in ignimbrites: a case study of the Cardones ignimbrite, Northern Chile. Bull. Volcanol. 80, 22 (2018).

    Google Scholar 

  39. 39.

    Kendrick, J. E. et al. Crystal plasticity as an indicator of the viscous–brittle transition in magmas. Nat. Commun. 8, 1926 (2017).

    Google Scholar 

  40. 40.

    Taddeucci, J. et al. In-flight dynamics of volcanic ballistic projectiles. Rev. Geophys. 55, 675–718 (2017).

    Google Scholar 

  41. 41.

    Moitra, P., Sonder, I. & Valentine, G. A. Effects of size and temperature-dependent thermal conductivity on the cooling of pyroclasts in air. Geochem. Geophys. Geosyst. 19, 3623–3636 (2018).

    Google Scholar 

  42. 42.

    Wadsworth, F. B., Llewellin, E. W., Vasseur, J., Gardner, J. E. & Tuffen, H. Explosive–effusive volcanic eruption transitions caused by sintering. Sci. Adv. 6, 7940 (2020).

    Google Scholar 

  43. 43.

    Del Gaudio, P., Ventura, G. & Taddeucci, J. The effect of particle size on the rheology of liquid-solid mixtures with application to lava flows: results from analogue experiments. Geochem. Geophys. Geosyst. 14, 2661–2669 (2013).

    Google Scholar 

  44. 44.

    Houghton, B. F., Wilson, C. J. N., Fierstein, J. & Hildreth, W. Complex proximal deposition during the Plinian eruptions of 1912 at Novarupta, Alaska. Bull. Volcanol. 66, 95–133 (2004).

    Google Scholar 

  45. 45.

    Polacci, M., Baker, D. R., Bai, L. & Mancini, L. Large vesicles record pathways of degassing at basaltic volcanoes. Bull. Volcanol. 70, 1023–1029 (2008).

    Google Scholar 

  46. 46.

    Lamur, A., Kendrick, J. E., Wadsworth, F. B. & Lavallée, Y. Fracture healing and strength recovery in magmatic liquids. Geology 47, 195–198 (2019).

    Google Scholar 

  47. 47.

    Cashman, K. V. & Marsh, B. D. Crystal size distribution (CSD) in rocks and the kinetics and dynamics of crystallization II: Makaopuhi lava lake. Contrib. Mineral. Petrol. 99, 292–305 (1988).

    Google Scholar 

  48. 48.

    Baker, D. R. et al. A four-dimensional X-ray tomographic microscopy study of bubble growth in basaltic foam. Nat. Commun. 3, 1135 (2012).

    Google Scholar 

  49. 49.

    Dürig, T. & Zimanowski, B. ‘Breaking news’ on the formation of volcanic ash: fracture dynamics in silicate glass. Earth Planet. Sci. Lett. 335–336, 1–8 (2012).

    Google Scholar 

  50. 50.

    Polacci, M., Corsaro, R. A. & Andronico, D. Coupled textural and compositional characterization of basaltic scoria: insights into the transition from Strombolian to fire fountain activity at Mount Etna, Italy. Geology 34, 201–204 (2006).

    Google Scholar 

  51. 51.

    Sable, J. E., Houghton, B. F., Del Carlo, P. & Coltelli, M. Changing conditions of magma ascent and fragmentation during the Etna 122 BC basaltic Plinian eruption: evidence from clast microtextures. J. Volcanol. Geotherm. Res. 158, 333–354 (2006).

    Google Scholar 

  52. 52.

    Costantini, L., Houghton, B. F. & Bonadonna, C. Constraints on eruption dynamics of basaltic explosive activity derived from chemical and microtextural study: the example of the Fontana Lapilli Plinian eruption, Nicaragua. J. Volcanol. Geotherm. Res. 189, 207–224 (2010).

    Google Scholar 

  53. 53.

    Pompilio, M., Bertagnini, A., Del Carlo, P. & Di Roberto, A. Magma dynamics within a basaltic conduit revealed by textural and compositional features of erupted ash: the December 2015 Mt. Etna paroxysms. Sci. Rep. 7, 4805 (2017).

    Google Scholar 

  54. 54.

    Suzuki, Y. & Fujii, T. Effect of syneruptive decompression path on shifting intensity in basaltic sub-Plinian eruption: implication of microlites in Yufune-2 scoria from Fuji volcano, Japan. J. Volcanol. Geotherm. Res. 198, 158–176 (2010).

    Google Scholar 

  55. 55.

    Wall, K. T., Rowe, M. C., Ellis, B. S., Schmidt, M. E. & Eccles, J. D. Determining volcanic eruption styles on Earth and Mars from crystallinity measurements. Nat. Commun. 5, 5090 (2014).

    Google Scholar 

  56. 56.

    Cannata, C. B. et al. First 3D imaging characterization of Pele’s hair from Kilauea volcano (Hawaii). Sci. Rep. 9, 1711 (2019).

    Google Scholar 

  57. 57.

    Holt, S. J. et al. Eruption and fountaining dynamics of selected 1985–1986 high fountaining episodes at Kīlauea volcano, Hawai’i, from quantitative vesicle microtexture analysis. J. Volcanol. Geotherm. Res. 369, 21–34 (2019).

    Google Scholar 

  58. 58.

    Lormand, C. et al. Slow ascent of unusually hot intermediate magmas triggering Strombolian to Plinian eruptions. J. Petrol. (2020).

  59. 59.

    Gardner, J. E., Llewellin, E. W., Watkins, J. M. & Befus, K. S. Formation of obsidian pyroclasts by sintering of ash particles in the volcanic conduit. Earth Planet. Sci. Lett. 459, 252–263 (2017).

    Google Scholar 

  60. 60.

    Tuffen, H., Dingwell, D. B. & Pinkerton, H. Repeated fracture and healing of silicic magma generate flow banding and earthquakes? Geology 31, 1089–1092 (2003).

    Google Scholar 

  61. 61.

    Tadeucci, J., Pompilio, M. & Scarlato, P. Monitoring the explosive activity of the July–August 2001 eruption of Mt. Etna (Italy) by ash characterization. Geophys. Res. Lett. 29, 1230 (2002).

    Google Scholar 

  62. 62.

    Andronico, D. et al. A multi-disciplinary study of the 2002–03 Etna eruption: insights into a complex plumbing system. Bull. Volcanol. 67, 314–330 (2005).

    Google Scholar 

  63. 63.

    Pioli, L. et al. in The Stromboli Volcano: An Integrated Study of the 2002–2003 Eruption (eds Calvari, S. et al.) 105–115 (AGU, 2008).

  64. 64.

    Di Traglia, F., Cimarelli, C., de Rita, D. & Gimeno Torrente, D. Changing eruptive styles in basaltic explosive volcanism: examples from Croscat complex scoria cone, Garrotxa Volcanic Field (NE Iberian Peninsula). J. Volcanol. Geotherm. Res. 180, 89–109 (2009).

    Google Scholar 

  65. 65.

    Delgado, H. et al. Geology of Xitle volcano in southern Mexico City – A 2000-year-old monogenetic volcano in an urban area. Rev. Mex. Cienc. Geol. 15, 115–131 (1998).

    Google Scholar 

  66. 66.

    Gudmundsson, M. T. et al. Ash generation and distribution from the April–May 2010 eruption of Eyjafjallajökull, Iceland. Sci. Rep. 2, 572 (2012).

    Google Scholar 

  67. 67.

    Viccaro, M. et al. Shallow conduit dynamics fuel the unexpected paroxysms of Stromboli volcano during the summer 2019. Sci. Rep. 11, 266 (2021).

    Google Scholar 

  68. 68.

    Giordano, G. & De Astis, G. The summer 2019 basaltic Vulcanian eruptions (paroxysms) of Stromboli. Bull. Volcanol. 83, 1 (2021).

    Google Scholar 

  69. 69.

    Naismith, A. K. et al. Eruption frequency patterns through time for the current (1999–2018) activity cycle at Volcán de Fuego derived from remote sensing data: evidence for an accelerating cycle of explosive paroxysms and potential implications of eruptive activity. J. Volcanol. Geotherm. Res. 371, 206–219 (2019).

    Google Scholar 

  70. 70.

    Rosi, M. et al. Stromboli volcano, Aeolian Islands (Italy): present eruptive activity and hazards. Geol. Soc. Mem. 37, 473–490 (2013).

    Google Scholar 

  71. 71.

    Lloyd, A. S. et al. NanoSIMS results from olivine-hosted melt embayments: magma ascent rate during explosive basaltic eruptions. J. Volcanol. Geotherm. Res. 283, 1–18 (2014).

    Google Scholar 

  72. 72.

    Armienti, P., Perinelli, C. & Putirka, K. D. A new model to estimate deep-level magma ascent rates, with applications to Mt. Etna (Sicily, Italy). J. Petrol. 54, 795–813 (2013).

    Google Scholar 

  73. 73.

    Ripepe, M., Harris, A. J. L. & Carniel, R. Thermal, seismic and infrasonic evidences of variable degassing rates at Stromboli volcano. J. Volcanol. Geotherm. Res. 118, 285–297 (2002).

    Google Scholar 

  74. 74.

    Cervantes, P. & Wallace, P. Magma degassing and basaltic eruption styles: a case study of 2000 year BP Xitle volcano in central Mexico. J. Volcanol. Geotherm. Res. 120, 249–270 (2003).

    Google Scholar 

  75. 75.

    Corsaro, R. A., Miraglia, L. & Pompilio, M. Petrologic evidence of a complex plumbing system feeding the July–August 2001 eruption of Mt. Etna, Sicily, Italy. Bull. Volcanol. 69, 401–421 (2007).

    Google Scholar 

  76. 76.

    Pioli, L. et al. Explosive dynamics of violent Strombolian eruptions: the eruption of Parícutin Volcano 1943-1952 (Mexico). Earth Planet. Sci. Lett. 271, 359–368 (2008).

    Google Scholar 

  77. 77.

    Berlo, K., Stix, J., Roggensack, K. & Ghaleb, B. A tale of two magmas, Fuego, Guatemala. Bull. Volcanol. 74, 377–390 (2012).

    Google Scholar 

  78. 78.

    Di Stefano, F. et al. Mush cannibalism and disruption recorded by clinopyroxene phenocrysts at Stromboli volcano: new insights from recent 2003–2017 activity. Lithos 360–361, 105440 (2020).

    Google Scholar 

  79. 79.

    Cimarelli, C., Di Traglia, F. & Taddeucci, J. Basaltic scoria textures from a zoned conduit as precursors to violent Strombolian activity. Geology 38, 439–442 (2010).

    Google Scholar 

  80. 80.

    Andronico, D., Cristaldi, A., Del Carlo, P. & Taddeucci, J. Shifting styles of basaltic explosive activity during the 2002–03 eruption of Mt. Etna, Italy. J. Volcanol. Geotherm. Res. 180, 110–122 (2009).

    Google Scholar 

  81. 81.

    Erlund, E. J. et al. Compositional evolution of magma from Parícutin Volcano, Mexico: the tephra record. J. Volcanol. Geotherm. Res. 197, 167–187 (2010).

    Google Scholar 

  82. 82.

    Giordano, D., Russell, J. K. & Dingwell, D. B. Viscosity of magmatic liquids: a model. Earth Planet. Sci. Lett. 271, 123–134 (2008).

    Google Scholar 

  83. 83.

    Vona, A., Romano, C., Dingwell, D. B. & Giordano, D. The rheology of crystal-bearing basaltic magmas from Stromboli and Etna. Geochim. Cosmochim. Acta 75, 3214–3236 (2011).

    Google Scholar 

  84. 84.

    Gardner, J. E., Ketcham, R. A. & Moore, G. Surface tension of hydrous silicate melts: constraints on the impact of melt composition. J. Volcanol. Geotherm. Res. 267, 68–74 (2013).

    Google Scholar 

  85. 85.

    Saubin, E. et al. Conduit dynamics in transitional rhyolitic activity recorded by tuffisite vein textures from the 2008–2009 Chaitén eruption. Front. Earth Sci. 4, 59 (2016).

    Google Scholar 

  86. 86.

    Gaudin, D. et al. Pyroclast tracking velocimetry illuminates bomb ejection and explosion dynamics at Stromboli (Italy) and Yasur (Vanuatu) volcanoes. J. Geophys. Res. Solid Earth 119, 5384–5397 (2014).

    Google Scholar 

  87. 87.

    Capponi, A., Taddeucci, J., Scarlato, P. & Palladino, D. M. Recycled ejecta modulating Strombolian explosions. Bull. Volcanol. 78, 1–13 (2016).

    Google Scholar 

  88. 88.

    Lesher, C. E. & Spera, F. J. in The Encyclopedia of Volcanoes 113–141 (Elsevier, 2015).

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M. Nazzari provided essential support during the FESEM analyses. Partial financial support from INGV (project UNO) to J.T., Deutsche Forschungsgemeinschaft project CI 254/2-1 to C.C. and DGAPA-UNAM to H.D.-G. is acknowledged. B. Zimanowski, R. Büttner and I. Sonder are acknowledged for the fragmentation experiments.

Author information




J.T. conceptualized this study, contributed to sample collection and fragmentation experiments and performed the majority of FESEM analyses. C.C., M.A.A.-I. and H.D.-G. contributed to conceptualize the study and to sample collection and FESEM analyses. D.A., P.S., E.D.B. and F.D.S. contributed to sample collection and FESEM analyses. All authors wrote the manuscript together.

Corresponding author

Correspondence to J. Taddeucci.

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The authors declare no competing interests.

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Peer review information Nature Geoscience thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editors: Rebecca Neely.

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Extended data

Extended Data Fig. 1 Spatial distribution and fracture orientation of broken crystals within one pyroclast.

a, Bi-dimensional fracture number density (number of fractures per mm2, in red), and percent of plagioclase crystal fragments over the total number of plagioclase crystals (fragments plus unbroken, in black) within the individual images of the mosaic. Note the higher fracture density and percent of broken crystals along the margins of the particle despite uniform crystallinity all through the clast. b, Direction of extension (parallel to red dash) for broken crystal with extensional features (see, for example, Fig. 1k). No preferred orientation is visible. In the inset, the mosaic of the whole pyroclast, with the outline of the investigated area marked in white.

Source data

Extended Data Fig. 2 Scanning electron micrographs of volcanic particles with additional features of broken crystals and healing fractures.

a-c, Ash-sized pyroclasts fringed by broken crystals, reflecting the propagation of large, clast-forming fractures and smaller ones that healed after breaking the crystals. d-f, Transitions between clast- and crystal-cutting fractures. Open fractures (d) surrounded by broken crystals with glass-filled fractures. e,f, A fracture almost dividing an entire clast, except for a narrow, viscously healed portion with vesicles and broken crystals. g, Flow banding of Fe-rich glass around broken crystals. h-j, Dispersal of crystal fragments marks post-fracture melt flow direction, with a rotational flow component (i) or shearing similar to boudinage (j). k-o, Features of broken crystals in microcrystalline groundmass are identical to those in glassy groundmass (see previous figures). Note the intermingling of the two types of groundmass (k,n), and the presence of nano-scale Fe-oxide crystals in the crystal-cutting fracture infill (o). Red boxes are enlarged in the subsequent panel.

Extended Data Fig. 3 Scanning electron micrographs of experimental products showing additional transitions between fractures, vesicles, and broken crystals.

a-c, Progressive zooms into the terminal part of a large fracture (same as in Fig. 3a), with viscous healing isolating vesicles of variable size. d-i, Transitions between small, fracture-derived vesicles (d,e) and broken crystals with open (f-h) and glass-filled fractures (g,i). j-k, Train of vesicles within one experimental product (j). Vesicle alignment and the surrounding broken crystals (k) reveal their fracture-related origin. l, Wisps of Fe-rich glass marking sutured fractures. m, Viscous healing dispersing crystal fragments and forming flow banding of Fe-rich melt. n,o, Flow banding of Fe-rich melt induced by syn-experimental deformation of the melt after fragmentation, with entrained broken crystals (o). Red boxes are enlarged in the subsequent panel.

Extended Data Table 1 Crystallinity measurements of the experimental products and of natural pyroclasts from selected samples.

Crystallinity is calculated on a vesicle-free basis.

Source data

Supplementary information

Supplementary Information

Supplementary Data 1 and 2.

Supplementary Video

High-speed video of a fragmentation experiment filmed from above at 5,000 frames per second (see Fig. 2 for selected still frames). The inner diameter of the circular crucible is 10 cm.

Source data

Source Data Fig. 4

Raw measurements of fracture parameters in volcanic and experimental products.

Source Data Extended Data Fig. 1

Point count measurements of intact crystals, crystal fragments, and vesicle-free area for all the 30 images of the mosaic in Extended Data Fig. 1.

Source Data Extended Data Table 1

Point count and image segmentation crystallinity for all measured images of natural and experimental products.

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Taddeucci, J., Cimarelli, C., Alatorre‑Ibargüengoitia, M.A. et al. Fracturing and healing of basaltic magmas during explosive volcanic eruptions. Nat. Geosci. 14, 248–254 (2021).

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