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.
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
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, https://doi.org/10.17632/h5ynspf336.1, 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, https://doi.org/10.17632/38rss8f2yb.1 and presented in the source data provided with this paper.
Wilson, L. Volcanism in the solar system. Nat. Geosci. 2, 389–397 (2009).
Gonnermann, H. M. Magma fragmentation. Annu. Rev. Earth Planet. Sci. 43, 431–458 (2015).
Papale, P. Global time-size distribution of volcanic eruptions on Earth. Sci. Rep. 8, 1–11 (2018).
Houghton, B. F. & Gonnermann, H. M. Basaltic explosive volcanism: constraints from deposits and models. Chem. Erde 68, 117–140 (2008).
Taddeucci, J., Edmonds, M., Houghton, B., James, M. R. & Vergniolle, S. in The Encyclopedia of Volcanoes 485–503 (Elsevier, 2015).
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).
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).
Cashman, K. V. & Scheu, B. in The Encyclopedia of Volcanoes 459–471 (Elsevier, 2015).
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).
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).
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).
Green, F. H. Y. et al. Is volcanic ash a pneumoconiosis risk? Nature 293, 216–217 (1981).
Alvarado, J. A. C. et al. Anthropogenic radionuclides in atmospheric air over Switzerland during the last few decades. Nat. Commun. 5, 3030 (2014).
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).
Dingwell, D. B. Volcanic dilemma: flow or blow. Science 273, 1054–1055 (1996).
Zhang, Y. A criterion for the fragmentation of bubbly magma based on brittle failure theory. Nature 402, 648–650 (1999).
Gonnermann, H. M. & Manga, M. Explosive volcanism may not be an inevitable consequence of magma fragmentation. Nature 426, 432–435 (2003).
Spieler, O. et al. The fragmentation threshold of pyroclastic rocks. Earth Planet. Sci. Lett. 226, 139–148 (2004).
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).
Namiki, A. & Manga, M. Transition between fragmentation and permeable outgassing of low viscosity magmas. J. Volcanol. Geotherm. Res. 169, 48–60 (2008).
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).
Jones, T. J., Reynolds, C. D. & Boothroyd, S. C. Fluid dynamic induced break-up during volcanic eruptions. Nat. Commun. 10, 3828 (2019).
Büttner, R., Dellino, P. & Zimanowski, B. Identifying magma–water interaction from the surface features of ash particles. Nature 401, 688–690 (1999).
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).
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).
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).
Arzilli, F. et al. Magma fragmentation in highly explosive basaltic eruptions induced by rapid crystallization. Nat. Geosci. 12, 1023–1028 (2019).
Zimanowski, B., Wohletz, K., Dellino, P. & Büttner, R. The volcanic ash problem. J. Volcanol. Geotherm. Res. 122, 1–5 (2003).
Dellino, P. et al. Ash from the Eyjafjallajökull eruption (Iceland): fragmentation processes and aerodynamic behavior. J. Geophys. Res. Solid Earth 117, B00C04 (2012).
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).
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).
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).
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).
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).
Bindeman, I. N. Fragmentation phenomena in populations of magmatic crystals. Am. Mineral. 90, 1801–1815 (2005).
Kennedy, B. et al. Conduit implosion during Vulcanian eruptions. Geology 33, 581–584 (2005).
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).
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).
Kendrick, J. E. et al. Crystal plasticity as an indicator of the viscous–brittle transition in magmas. Nat. Commun. 8, 1926 (2017).
Taddeucci, J. et al. In-flight dynamics of volcanic ballistic projectiles. Rev. Geophys. 55, 675–718 (2017).
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).
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).
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).
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).
Polacci, M., Baker, D. R., Bai, L. & Mancini, L. Large vesicles record pathways of degassing at basaltic volcanoes. Bull. Volcanol. 70, 1023–1029 (2008).
Lamur, A., Kendrick, J. E., Wadsworth, F. B. & Lavallée, Y. Fracture healing and strength recovery in magmatic liquids. Geology 47, 195–198 (2019).
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).
Baker, D. R. et al. A four-dimensional X-ray tomographic microscopy study of bubble growth in basaltic foam. Nat. Commun. 3, 1135 (2012).
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).
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).
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).
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).
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).
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).
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).
Cannata, C. B. et al. First 3D imaging characterization of Pele’s hair from Kilauea volcano (Hawaii). Sci. Rep. 9, 1711 (2019).
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).
Lormand, C. et al. Slow ascent of unusually hot intermediate magmas triggering Strombolian to Plinian eruptions. J. Petrol. https://doi.org/10.1093/petrology/egaa077 (2020).
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).
Tuffen, H., Dingwell, D. B. & Pinkerton, H. Repeated fracture and healing of silicic magma generate flow banding and earthquakes? Geology 31, 1089–1092 (2003).
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).
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).
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).
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).
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).
Gudmundsson, M. T. et al. Ash generation and distribution from the April–May 2010 eruption of Eyjafjallajökull, Iceland. Sci. Rep. 2, 572 (2012).
Viccaro, M. et al. Shallow conduit dynamics fuel the unexpected paroxysms of Stromboli volcano during the summer 2019. Sci. Rep. 11, 266 (2021).
Giordano, G. & De Astis, G. The summer 2019 basaltic Vulcanian eruptions (paroxysms) of Stromboli. Bull. Volcanol. 83, 1 (2021).
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).
Rosi, M. et al. Stromboli volcano, Aeolian Islands (Italy): present eruptive activity and hazards. Geol. Soc. Mem. 37, 473–490 (2013).
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).
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).
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).
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).
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).
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).
Berlo, K., Stix, J., Roggensack, K. & Ghaleb, B. A tale of two magmas, Fuego, Guatemala. Bull. Volcanol. 74, 377–390 (2012).
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).
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).
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).
Erlund, E. J. et al. Compositional evolution of magma from Parícutin Volcano, Mexico: the tephra record. J. Volcanol. Geotherm. Res. 197, 167–187 (2010).
Giordano, D., Russell, J. K. & Dingwell, D. B. Viscosity of magmatic liquids: a model. Earth Planet. Sci. Lett. 271, 123–134 (2008).
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).
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).
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).
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).
Capponi, A., Taddeucci, J., Scarlato, P. & Palladino, D. M. Recycled ejecta modulating Strombolian explosions. Bull. Volcanol. 78, 1–13 (2016).
Lesher, C. E. & Spera, F. J. in The Encyclopedia of Volcanoes 113–141 (Elsevier, 2015).
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.
The authors declare no competing interests.
Peer review information Nature Geoscience thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editors: Rebecca Neely.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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.
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.
Raw measurements of fracture parameters in volcanic and experimental products.
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.
Point count and image segmentation crystallinity for all measured images of natural and experimental products.
About this article
Cite this article
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). https://doi.org/10.1038/s41561-021-00708-1
Nature Geoscience (2021)
A petrological and conceptual model of Mayon volcano (Philippines) as an example of an open-vent volcano
Bulletin of Volcanology (2021)
Quantitative chemical mapping of plagioclase as a tool for the interpretation of volcanic stratigraphy: an example from Saint Kitts, Lesser Antilles
Bulletin of Volcanology (2021)